This paper presents a numerical simulation of combustion processes in a gun barrel using a one-dimensional two-phase flow model. The analysis accounts for the interphase drag and intergranular stress between the solid and gas phases. A flux-corrected transport scheme is used to study pressure wave propagation and flame dynamics during combustion. The model equations for mass, momentum and energy are solved for the solid and gas phases coupled through appropriate interactions.
This document provides a course plan for a class on Gas Dynamics and Jet Propulsion taught by Mr. R. Deepak at KIT-Kalaignar Karunanidhi Institute of Technology. The course covers 5 units: basic concepts and isentropic flows, flow through ducts, normal and oblique shocks, jet propulsion, and space propulsion. The course aims to help students understand compressible flow, shock waves, and jet and rocket propulsion. It includes learning objectives, outcomes, assignments, exams, reference materials and an evaluation plan following Anna University guidelines.
This document contains lecture notes on mass transfer operations. It discusses various topics including diffusion, gas-liquid operations like absorption, and vapor-liquid operations like distillation.
The key points covered are:
1) Diffusion is the process of mass transfer between regions of different concentrations due to random molecular motion. Pick's law describes the rate of diffusion.
2) Gas absorption involves the removal of a soluble gas from a mixture by absorption into a liquid. Absorption towers can be analyzed using the concept of gas transfer units.
3) Distillation separates components based on volatility. Batch distillation methods include differential and flash distillation. Continuous rectification in distillation columns can be modeled using material balances
The document discusses column efficiency in chromatography. It introduces the van Deemter equation, which describes the factors that influence column efficiency through the plate height (H). The factors are eddy diffusion (A term), longitudinal diffusion (B term), and resistance to mass transfer (C term). Smaller particle size, better packing, and optimal flow rate can improve efficiency by minimizing the terms in the van Deemter equation. The C term, in particular, increases with flow rate, so there is an optimal flow where efficiency is highest.
Chap 1(a) molecular-diffusion_in_gas(2)Charice Wan
The document discusses principles of molecular diffusion in gases. It covers topics such as equimolar counter diffusion, diffusion through cross-sectional areas like spheres, and calculating diffusion coefficients. Examples and problems are provided to demonstrate how to calculate flux and diffusion rates in various scenarios, including diffusion between binary gas mixtures and evaporation from surfaces. Methods for estimating gas diffusivity are also presented.
Dimensional analysis Similarity laws Model laws R A Shah
Rayleigh's method- Theory and Examples
Buckingham Pi Theorem- Theory and Examples
Model and Similitude
Forces on Fluid
Dimensionless Numbers
Model laws
Distorted models
This document provides an overview of mass transfer and diffusion. It begins with definitions of mass transfer and examples of mass transfer processes. It then discusses various topics related to mass transfer, including:
- Classification of mass transfer operations based on the phases in contact
- Mechanisms of convective and diffusive mass transfer
- The mass transfer coefficient and different types of mass transfer coefficients
- Dimensionless groups used in mass transfer like the Sherwood number
- Theories of mass transfer including the film theory and penetration theory
It provides explanations of key concepts in mass transfer and diffusion, along with relevant equations. The document serves as a reference for various fundamental aspects of mass transfer.
An Experimental Study of the Effect of Partial Premixing Level on the Interac...Waqas Tariq
Flame kernels in spark-ignited combustion systems dominate the flame propagation and combustion stability, performance and emissions. The aim of the present work is to investigate the flow field associated with flame kernel propagation history in partial premixing natural gas turbulent flames. The main parameters under investigation are the degree of partial premixing and jet velocity. Three different degrees of partial premixing and five values of jet velocity between10 and 20 m/s have been selected for the present work at an equivalence ratio of 2. The mean flow field and turbulence intensity are measured using two-dimensional Planar Imaging Velocimetry (PIV). A pulsed Nd: YAG laser is used for flame ignition. The turbulent flow field is captured after the ignition at several time intervals between, 150, and 2500 ?s after ignition. The results show that the flame kernel does not show any significant effect on the scale of mean flow field. On the other hand, the flame kernel increases the global turbulence intensity in flames in comparison with the isothermal cases. The flame kernel propagation is associated with a steep increase in the centerline turbulence intensity of the jet flow. An increase in the degree of partial premixing and/or the jet velocity increases the centerline turbulence intensity accompanying the flame kernel propagation. This leads to break-up of the degree of partial premixing of the flame structure, and hence, decreased flame stability. Also, the higher the degree of partial premixing or the higher the jet velocity leads to more rapid flame kernel extinction. The results show that the rate of flame kernel propagation is very fast at the early stage of the kernel propagation up to the first 300 ?s and then it slows down afterwards.
This document provides a course plan for a class on Gas Dynamics and Jet Propulsion taught by Mr. R. Deepak at KIT-Kalaignar Karunanidhi Institute of Technology. The course covers 5 units: basic concepts and isentropic flows, flow through ducts, normal and oblique shocks, jet propulsion, and space propulsion. The course aims to help students understand compressible flow, shock waves, and jet and rocket propulsion. It includes learning objectives, outcomes, assignments, exams, reference materials and an evaluation plan following Anna University guidelines.
This document contains lecture notes on mass transfer operations. It discusses various topics including diffusion, gas-liquid operations like absorption, and vapor-liquid operations like distillation.
The key points covered are:
1) Diffusion is the process of mass transfer between regions of different concentrations due to random molecular motion. Pick's law describes the rate of diffusion.
2) Gas absorption involves the removal of a soluble gas from a mixture by absorption into a liquid. Absorption towers can be analyzed using the concept of gas transfer units.
3) Distillation separates components based on volatility. Batch distillation methods include differential and flash distillation. Continuous rectification in distillation columns can be modeled using material balances
The document discusses column efficiency in chromatography. It introduces the van Deemter equation, which describes the factors that influence column efficiency through the plate height (H). The factors are eddy diffusion (A term), longitudinal diffusion (B term), and resistance to mass transfer (C term). Smaller particle size, better packing, and optimal flow rate can improve efficiency by minimizing the terms in the van Deemter equation. The C term, in particular, increases with flow rate, so there is an optimal flow where efficiency is highest.
Chap 1(a) molecular-diffusion_in_gas(2)Charice Wan
The document discusses principles of molecular diffusion in gases. It covers topics such as equimolar counter diffusion, diffusion through cross-sectional areas like spheres, and calculating diffusion coefficients. Examples and problems are provided to demonstrate how to calculate flux and diffusion rates in various scenarios, including diffusion between binary gas mixtures and evaporation from surfaces. Methods for estimating gas diffusivity are also presented.
Dimensional analysis Similarity laws Model laws R A Shah
Rayleigh's method- Theory and Examples
Buckingham Pi Theorem- Theory and Examples
Model and Similitude
Forces on Fluid
Dimensionless Numbers
Model laws
Distorted models
This document provides an overview of mass transfer and diffusion. It begins with definitions of mass transfer and examples of mass transfer processes. It then discusses various topics related to mass transfer, including:
- Classification of mass transfer operations based on the phases in contact
- Mechanisms of convective and diffusive mass transfer
- The mass transfer coefficient and different types of mass transfer coefficients
- Dimensionless groups used in mass transfer like the Sherwood number
- Theories of mass transfer including the film theory and penetration theory
It provides explanations of key concepts in mass transfer and diffusion, along with relevant equations. The document serves as a reference for various fundamental aspects of mass transfer.
An Experimental Study of the Effect of Partial Premixing Level on the Interac...Waqas Tariq
Flame kernels in spark-ignited combustion systems dominate the flame propagation and combustion stability, performance and emissions. The aim of the present work is to investigate the flow field associated with flame kernel propagation history in partial premixing natural gas turbulent flames. The main parameters under investigation are the degree of partial premixing and jet velocity. Three different degrees of partial premixing and five values of jet velocity between10 and 20 m/s have been selected for the present work at an equivalence ratio of 2. The mean flow field and turbulence intensity are measured using two-dimensional Planar Imaging Velocimetry (PIV). A pulsed Nd: YAG laser is used for flame ignition. The turbulent flow field is captured after the ignition at several time intervals between, 150, and 2500 ?s after ignition. The results show that the flame kernel does not show any significant effect on the scale of mean flow field. On the other hand, the flame kernel increases the global turbulence intensity in flames in comparison with the isothermal cases. The flame kernel propagation is associated with a steep increase in the centerline turbulence intensity of the jet flow. An increase in the degree of partial premixing and/or the jet velocity increases the centerline turbulence intensity accompanying the flame kernel propagation. This leads to break-up of the degree of partial premixing of the flame structure, and hence, decreased flame stability. Also, the higher the degree of partial premixing or the higher the jet velocity leads to more rapid flame kernel extinction. The results show that the rate of flame kernel propagation is very fast at the early stage of the kernel propagation up to the first 300 ?s and then it slows down afterwards.
The document discusses dimensional analysis and dimensionless numbers. It defines dimensionless numbers as ratios of different forces that give a dimensionless quantity. Some important dimensionless numbers discussed are Reynolds number, Froude number, Euler number, Weber number, and Mach number. Equations for each of these numbers are provided showing the ratio of inertia force to viscous, gravity, pressure, surface tension, and elastic forces respectively. Methods of dimensional analysis including Rayleigh's method and Buckingham π-theorem are also summarized. Repeating variables, their selection criteria, and example problems applying Buckingham π-theorem are outlined in brief.
This document outlines the contents of the course ME 6604 Gas Dynamics and Jet Propulsion. It contains 5 units:
1. Basic concepts and isentropic flows, including concepts of compressible flow, stagnation properties, and flow through nozzles and diffusers.
2. Flow through ducts, including Fanno flow with friction and Rayleigh flow with heat transfer.
3. Normal and oblique shocks, including governing equations and properties across shock waves.
4. Jet propulsion, including theories of jet propulsion and performance of ramjets, turbojets, turbofans and turboprops.
5. Space propulsion, including rocket propulsion principles, types of rocket
This document contains lecture slides from Dr. M. Subas Chandra Bose and Mrs. Sabarunisha Begum on the topic of mass transfer operations. It discusses various mass transfer concepts like diffusion, gas absorption principles, and vapor-liquid operations including distillation. The slides provide definitions and examples of different mass transfer processes and operations. They also describe concepts like the transfer unit, differential distillation, flash distillation, and continuous rectification in binary systems.
Radiation and Mass Transfer Effects on MHD Natural Convection Flow over an In...IJMER
A numerical solution for the unsteady, natural convective flow of heat and mass transfer along an inclined plate is presented. The dimensionless unsteady, coupled, and non-linear partial differential conservation equations for the boundary layer regime are solved by an efficient, accurate and unconditionally stable finite difference scheme of the Crank-Nicolson type. The velocity, temperature, and concentration fields have been studied for the effect of Magnetic parameter, buoyancy ratio parameter, Prandtl number, radiation parameter and Schmidt number. The local skin-friction, Nusselt number and Sherwood number are also presented and analyzed graphically.
Fluid Mechanics Chapter 4. Differential relations for a fluid flowAddisu Dagne Zegeye
Introduction, Acceleration field, Conservation of mass equation, Linear momentum equation, Energy equation, Boundary condition, Stream function, Vorticity and Irrotationality
Investigation of the Effect of Nanoparticles Mean Diameter on Turbulent Mixed...A Behzadmehr
Abstract
Turbulent mixed convection of a nanofluid (water/Al2O3, Φ=.02) has been studied numerically. Two-phase
mixture model has been used to investigate the effects of nanoparticles mean diameter on the flow parameters. Nanoparticles distribution at the tube cross section shows that the particles are uniformly dispersed. The non-uniformity of the particles distribution occurs in the case of large nanoparticles and/or high value of the Grashof numbers. The study of particle size effect showed that the effective Nusselt number and turbulent intensity increases with the decreased of particle size.
Multi-scale time integration for transient conjugate heat transferMohamed Fadl
The paper proposes a new multi-scale framework for transient conjugate heat transfer simulations to address limitations of the quasi-steady assumption commonly used. The framework adopts a triple-timing form to integrate the fluid domain equations, capturing both the slow time scales of the solid domain through a source term and the short time scales of the fluid domain through local time integration at frozen large time steps. Preliminary validation studies indicate the method can achieve enhanced applicability with relatively small modifications to existing transient conjugate heat transfer methods at low additional cost compared to quasi-steady approaches.
This document summarizes previous numerical studies of detonation waves in premixed hydrogen-air mixtures and assesses the accuracy of simplified chemical reaction mechanisms. It describes the classical ZND detonation wave structure and compares numerical results to ZND theory. Several chemical mechanisms of varying complexity are evaluated using zero-dimensional combustion simulations and one-dimensional detonation wave simulations. Comparisons to experimental detonation speeds help validate the chemical models. The document discusses limitations of previous studies and aims to better understand the effects of chemical kinetics models on computed detonation wave structures.
This document discusses the development and history of the SPRAY Lagrangian dispersion model code over several decades. It began in the 1980s as a collaboration between researchers in France and Italy to develop a particle-based Lagrangian model. The code was further developed in the 1990s by additional researchers in Italy. It has been used to model dispersion for applications like predicting pollutant concentrations. Key publications discussing updates to the model, like adding chemical reactions and testing against experimental data, are also summarized.
Meltblowing ii-linear and nonlinear waves on viscoelastic polymer jetsVinod Kumar
This document discusses linear and nonlinear waves on viscoelastic polymer jets in meltblowing processes. It first presents the governing equations for unperturbed straight polymer jets under the influence of a high-speed surrounding gas jet. It considers the effects of polymer viscoelasticity using an upper-convected Maxwell model. It then analyzes small perturbations using linear stability theory. Finally, it discusses the numerical solution of the fully nonlinear governing equations for large-amplitude bending perturbations, considering both isothermal and nonisothermal cases where jet cooling can arrest perturbation growth.
Dynamics of porous media at finite strainJ P Perez
This document presents a finite element model for analyzing the dynamics of porous media undergoing large deformations. It develops governing equations for momentum and mass conservation by writing them in Lagrangian form based on the motion of the solid matrix. Both a complete (v,vf)-formulation and an approximated (v,p)-formulation are presented. A compressible neo-Hookean material model with Kelvin viscous enhancement is used for the solid matrix. Numerical examples demonstrate the impact of large deformations on porous structure responses and the convergence of the iterative solution algorithm.
The document summarizes the development of a new small-bore light gas gun (LGG) launcher. Experimental analysis showed that the current dual-pressure breech design did not allow the sabot to reach its full potential velocity. 3D simulations of the breech's internal ballistics informed a redesign to a three-pressure system. The simulations indicated that increasing the gas flow rate through larger valve diameters and using a three-pressure breech with separate chambers for the driving pressure and launching piston would optimize performance and allow for more controlled collision velocities. Future work will include implementing and testing the new three-pressure breech design.
This document discusses modeling the effect of upstream temperature fluctuations on the interaction between shock waves and homogeneous turbulence. Linear analysis is used to study how upstream temperature fluctuations affect the amplification of turbulent kinetic energy (k) across a shock. The production term due to the mean pressure gradient is identified as the dominant mechanism through which upstream velocity-temperature correlation impacts k amplification. The model is modified to account for this based on linear theory results. Comparisons with DNS data show the new model provides significantly improved predictions over existing two-equation models.
Applications of Differential Equations in Petroleum EngineeringRaboon Redar
In modern science and engineering, differential equations are very important. Nearly all known physics and chemistry laws are indeed differential equations. Engineers, in order to investigate systems behavior, it is virtually necessary that they are able to model and solve physical problems with mathematical equations.
The understanding of two-phase flow and heat transfer
with phase change in minichannels is needed for the design and
optimization of heat exchangers and other industrial
applications. In this study a three-dimensional numerical model
has been developed to predict filmwise condensation heat
transfer inside a rectangular minichannel. The Volume of Fluid
(VOF) method is used to track the vapor-liquid interface. The
modified High Resolution Interface Capture (HRIC) scheme is
employed to keep the interface sharp. The governing equations
and the VOF equation with relevant source terms for
condensation are solved. The surface tension is taken into
account in the modeling and it is evaluated by the Continuum
Surface Force (CSF) approach. The simulation is performed
using the CFD software package, ANSYS FLUENT, and an inhouse
developed code. This in-house code is specifically
developed to calculate the source terms associated with phase
change. These terms are deduced from Hertz-Knudsen equation
based on the kinetic gas theory. The numerical results are
validated with data obtained from the open literature. The
standard k-ω model is applied to model the turbulence through
both the liquid and vapor phase. The numerical results show
that surface tension plays an important role in the condensation
heat transfer process. Heat transfer enhancement is obtained
due to the presence of the corners. The surface tension pulls the
liquid towards the corners and reduces the average thermal
resistance in the cross section.
Turbulence structure behind the shock in canonical shockvortical turbulence ...Jovan Belite Squad
This document discusses a study using direct numerical simulation (DNS) to examine the interaction between isotropic turbulence and a normal shock wave. High-resolution simulations were performed across a range of shock Mach numbers (1.1-2.2) and turbulent Reynolds numbers (10-45). The results showed that turbulence quantities from DNS converge to predictions of linear interaction analysis (LIA) as the turbulent Mach number decreases, demonstrating the importance of LIA. LIA was also extended to compute full post-shock flow fields, revealing how the shock significantly changes turbulence structures through symmetrization and increased strain-rotation correlation.
Validity Of Principle Of Exchange Of Stabilities Of Rivilin- Ericksen Fluid...IRJET Journal
This document presents research on establishing the validity of the Principle of Exchange of Stabilities (PES) for thermal convection of a Rivlin-Ericksen fluid layer in porous medium heated from below with variable gravity. The fluid layer contains suspended particles and is subjected to rotation. The linearized stability equations are formulated using an operator method. It is established that PES is valid for this problem under sufficient conditions, when the gravity field g(z) is nonnegative throughout the fluid layer. This is done by analyzing the resolvent of the linearized stability operator as a composition of integral operators and applying the method of positive operators to show the system has a single greatest eigenvalue.
The document discusses modeling turbulent premixed and partially premixed combustion. It notes that directly solving transport equations for all reactive species moments is impractical due to the large number of equations and closure terms required. Instead, models track the first two moments of one or two key scalars like mixture fraction and progress variable. The document reviews modeling approaches for lean premixed flames and describes the strained flamelet model and its extension to partially premixed flames. It discusses implementing the model in CFD codes and comparing results.
Physical Characterization of a Method for Production of High Stability Suspen...Editor IJCATR
Suspensions/Dispersions are encountered in a wide range of
applications, e.g., liquid abrasive cleaners, ceramics, medicines,
inks, paints….etc. In most cases it is necessary to keep the
suspension stable for the product lifetime. A new modified
differential sedimentation measuring system is suggested and used
to identify physical parameters affecting the sedimentation in
suspensions. The technique is discussed in details. It is found that
particle sizes as well as viscosity of continuous phase are the most
important factors governing the stability of a suspension. Empirical
relations are extracted to quantitatively describe the weight effect of
each factor. The modified measuring system shows good accuracy
enough to detect fluctuations in concentration of suspended
particles due to their Brownian diffusion, as well as the particles
concentrations in the stable suspension. This study confirmed the
fact that particles diameters measured by Zetasizer are much
greater than those measured by the transmission electron
microscope. This study presents a proposal for new technique for
particle size separation based on the differential sedimentation in
viscose fluids. This new method is a differential viscosity column.
The proposed size separation technique may help to separate
engineered nano-particles with higher resolution
Dynamic failure of composite and sandwich structuresSpringer
This document discusses research on the blast loading of sandwich composite materials and composite tubes. Air-blast and underwater-blast experiments were conducted using explosive charges ranging from 0.64-100 kg of TNT. High-speed photography and digital image correlation were used to monitor the deformation and failure mechanisms of glass fiber and carbon fiber sandwich panels under air-blast loading. Strain gauges were also used to monitor the response of similar sandwich materials and glass fiber tubes during underwater blast experiments. The experiments showed that underwater blast loading caused global core crushing in sandwich panels, while air-blast loading resulted in distributed core shear failure. The results provide data to develop analytical and computational models of blast loading and highlight the importance of boundary conditions in blast-
The document discusses dimensional analysis and dimensionless numbers. It defines dimensionless numbers as ratios of different forces that give a dimensionless quantity. Some important dimensionless numbers discussed are Reynolds number, Froude number, Euler number, Weber number, and Mach number. Equations for each of these numbers are provided showing the ratio of inertia force to viscous, gravity, pressure, surface tension, and elastic forces respectively. Methods of dimensional analysis including Rayleigh's method and Buckingham π-theorem are also summarized. Repeating variables, their selection criteria, and example problems applying Buckingham π-theorem are outlined in brief.
This document outlines the contents of the course ME 6604 Gas Dynamics and Jet Propulsion. It contains 5 units:
1. Basic concepts and isentropic flows, including concepts of compressible flow, stagnation properties, and flow through nozzles and diffusers.
2. Flow through ducts, including Fanno flow with friction and Rayleigh flow with heat transfer.
3. Normal and oblique shocks, including governing equations and properties across shock waves.
4. Jet propulsion, including theories of jet propulsion and performance of ramjets, turbojets, turbofans and turboprops.
5. Space propulsion, including rocket propulsion principles, types of rocket
This document contains lecture slides from Dr. M. Subas Chandra Bose and Mrs. Sabarunisha Begum on the topic of mass transfer operations. It discusses various mass transfer concepts like diffusion, gas absorption principles, and vapor-liquid operations including distillation. The slides provide definitions and examples of different mass transfer processes and operations. They also describe concepts like the transfer unit, differential distillation, flash distillation, and continuous rectification in binary systems.
Radiation and Mass Transfer Effects on MHD Natural Convection Flow over an In...IJMER
A numerical solution for the unsteady, natural convective flow of heat and mass transfer along an inclined plate is presented. The dimensionless unsteady, coupled, and non-linear partial differential conservation equations for the boundary layer regime are solved by an efficient, accurate and unconditionally stable finite difference scheme of the Crank-Nicolson type. The velocity, temperature, and concentration fields have been studied for the effect of Magnetic parameter, buoyancy ratio parameter, Prandtl number, radiation parameter and Schmidt number. The local skin-friction, Nusselt number and Sherwood number are also presented and analyzed graphically.
Fluid Mechanics Chapter 4. Differential relations for a fluid flowAddisu Dagne Zegeye
Introduction, Acceleration field, Conservation of mass equation, Linear momentum equation, Energy equation, Boundary condition, Stream function, Vorticity and Irrotationality
Investigation of the Effect of Nanoparticles Mean Diameter on Turbulent Mixed...A Behzadmehr
Abstract
Turbulent mixed convection of a nanofluid (water/Al2O3, Φ=.02) has been studied numerically. Two-phase
mixture model has been used to investigate the effects of nanoparticles mean diameter on the flow parameters. Nanoparticles distribution at the tube cross section shows that the particles are uniformly dispersed. The non-uniformity of the particles distribution occurs in the case of large nanoparticles and/or high value of the Grashof numbers. The study of particle size effect showed that the effective Nusselt number and turbulent intensity increases with the decreased of particle size.
Multi-scale time integration for transient conjugate heat transferMohamed Fadl
The paper proposes a new multi-scale framework for transient conjugate heat transfer simulations to address limitations of the quasi-steady assumption commonly used. The framework adopts a triple-timing form to integrate the fluid domain equations, capturing both the slow time scales of the solid domain through a source term and the short time scales of the fluid domain through local time integration at frozen large time steps. Preliminary validation studies indicate the method can achieve enhanced applicability with relatively small modifications to existing transient conjugate heat transfer methods at low additional cost compared to quasi-steady approaches.
This document summarizes previous numerical studies of detonation waves in premixed hydrogen-air mixtures and assesses the accuracy of simplified chemical reaction mechanisms. It describes the classical ZND detonation wave structure and compares numerical results to ZND theory. Several chemical mechanisms of varying complexity are evaluated using zero-dimensional combustion simulations and one-dimensional detonation wave simulations. Comparisons to experimental detonation speeds help validate the chemical models. The document discusses limitations of previous studies and aims to better understand the effects of chemical kinetics models on computed detonation wave structures.
This document discusses the development and history of the SPRAY Lagrangian dispersion model code over several decades. It began in the 1980s as a collaboration between researchers in France and Italy to develop a particle-based Lagrangian model. The code was further developed in the 1990s by additional researchers in Italy. It has been used to model dispersion for applications like predicting pollutant concentrations. Key publications discussing updates to the model, like adding chemical reactions and testing against experimental data, are also summarized.
Meltblowing ii-linear and nonlinear waves on viscoelastic polymer jetsVinod Kumar
This document discusses linear and nonlinear waves on viscoelastic polymer jets in meltblowing processes. It first presents the governing equations for unperturbed straight polymer jets under the influence of a high-speed surrounding gas jet. It considers the effects of polymer viscoelasticity using an upper-convected Maxwell model. It then analyzes small perturbations using linear stability theory. Finally, it discusses the numerical solution of the fully nonlinear governing equations for large-amplitude bending perturbations, considering both isothermal and nonisothermal cases where jet cooling can arrest perturbation growth.
Dynamics of porous media at finite strainJ P Perez
This document presents a finite element model for analyzing the dynamics of porous media undergoing large deformations. It develops governing equations for momentum and mass conservation by writing them in Lagrangian form based on the motion of the solid matrix. Both a complete (v,vf)-formulation and an approximated (v,p)-formulation are presented. A compressible neo-Hookean material model with Kelvin viscous enhancement is used for the solid matrix. Numerical examples demonstrate the impact of large deformations on porous structure responses and the convergence of the iterative solution algorithm.
The document summarizes the development of a new small-bore light gas gun (LGG) launcher. Experimental analysis showed that the current dual-pressure breech design did not allow the sabot to reach its full potential velocity. 3D simulations of the breech's internal ballistics informed a redesign to a three-pressure system. The simulations indicated that increasing the gas flow rate through larger valve diameters and using a three-pressure breech with separate chambers for the driving pressure and launching piston would optimize performance and allow for more controlled collision velocities. Future work will include implementing and testing the new three-pressure breech design.
This document discusses modeling the effect of upstream temperature fluctuations on the interaction between shock waves and homogeneous turbulence. Linear analysis is used to study how upstream temperature fluctuations affect the amplification of turbulent kinetic energy (k) across a shock. The production term due to the mean pressure gradient is identified as the dominant mechanism through which upstream velocity-temperature correlation impacts k amplification. The model is modified to account for this based on linear theory results. Comparisons with DNS data show the new model provides significantly improved predictions over existing two-equation models.
Applications of Differential Equations in Petroleum EngineeringRaboon Redar
In modern science and engineering, differential equations are very important. Nearly all known physics and chemistry laws are indeed differential equations. Engineers, in order to investigate systems behavior, it is virtually necessary that they are able to model and solve physical problems with mathematical equations.
The understanding of two-phase flow and heat transfer
with phase change in minichannels is needed for the design and
optimization of heat exchangers and other industrial
applications. In this study a three-dimensional numerical model
has been developed to predict filmwise condensation heat
transfer inside a rectangular minichannel. The Volume of Fluid
(VOF) method is used to track the vapor-liquid interface. The
modified High Resolution Interface Capture (HRIC) scheme is
employed to keep the interface sharp. The governing equations
and the VOF equation with relevant source terms for
condensation are solved. The surface tension is taken into
account in the modeling and it is evaluated by the Continuum
Surface Force (CSF) approach. The simulation is performed
using the CFD software package, ANSYS FLUENT, and an inhouse
developed code. This in-house code is specifically
developed to calculate the source terms associated with phase
change. These terms are deduced from Hertz-Knudsen equation
based on the kinetic gas theory. The numerical results are
validated with data obtained from the open literature. The
standard k-ω model is applied to model the turbulence through
both the liquid and vapor phase. The numerical results show
that surface tension plays an important role in the condensation
heat transfer process. Heat transfer enhancement is obtained
due to the presence of the corners. The surface tension pulls the
liquid towards the corners and reduces the average thermal
resistance in the cross section.
Turbulence structure behind the shock in canonical shockvortical turbulence ...Jovan Belite Squad
This document discusses a study using direct numerical simulation (DNS) to examine the interaction between isotropic turbulence and a normal shock wave. High-resolution simulations were performed across a range of shock Mach numbers (1.1-2.2) and turbulent Reynolds numbers (10-45). The results showed that turbulence quantities from DNS converge to predictions of linear interaction analysis (LIA) as the turbulent Mach number decreases, demonstrating the importance of LIA. LIA was also extended to compute full post-shock flow fields, revealing how the shock significantly changes turbulence structures through symmetrization and increased strain-rotation correlation.
Validity Of Principle Of Exchange Of Stabilities Of Rivilin- Ericksen Fluid...IRJET Journal
This document presents research on establishing the validity of the Principle of Exchange of Stabilities (PES) for thermal convection of a Rivlin-Ericksen fluid layer in porous medium heated from below with variable gravity. The fluid layer contains suspended particles and is subjected to rotation. The linearized stability equations are formulated using an operator method. It is established that PES is valid for this problem under sufficient conditions, when the gravity field g(z) is nonnegative throughout the fluid layer. This is done by analyzing the resolvent of the linearized stability operator as a composition of integral operators and applying the method of positive operators to show the system has a single greatest eigenvalue.
The document discusses modeling turbulent premixed and partially premixed combustion. It notes that directly solving transport equations for all reactive species moments is impractical due to the large number of equations and closure terms required. Instead, models track the first two moments of one or two key scalars like mixture fraction and progress variable. The document reviews modeling approaches for lean premixed flames and describes the strained flamelet model and its extension to partially premixed flames. It discusses implementing the model in CFD codes and comparing results.
Physical Characterization of a Method for Production of High Stability Suspen...Editor IJCATR
Suspensions/Dispersions are encountered in a wide range of
applications, e.g., liquid abrasive cleaners, ceramics, medicines,
inks, paints….etc. In most cases it is necessary to keep the
suspension stable for the product lifetime. A new modified
differential sedimentation measuring system is suggested and used
to identify physical parameters affecting the sedimentation in
suspensions. The technique is discussed in details. It is found that
particle sizes as well as viscosity of continuous phase are the most
important factors governing the stability of a suspension. Empirical
relations are extracted to quantitatively describe the weight effect of
each factor. The modified measuring system shows good accuracy
enough to detect fluctuations in concentration of suspended
particles due to their Brownian diffusion, as well as the particles
concentrations in the stable suspension. This study confirmed the
fact that particles diameters measured by Zetasizer are much
greater than those measured by the transmission electron
microscope. This study presents a proposal for new technique for
particle size separation based on the differential sedimentation in
viscose fluids. This new method is a differential viscosity column.
The proposed size separation technique may help to separate
engineered nano-particles with higher resolution
Dynamic failure of composite and sandwich structuresSpringer
This document discusses research on the blast loading of sandwich composite materials and composite tubes. Air-blast and underwater-blast experiments were conducted using explosive charges ranging from 0.64-100 kg of TNT. High-speed photography and digital image correlation were used to monitor the deformation and failure mechanisms of glass fiber and carbon fiber sandwich panels under air-blast loading. Strain gauges were also used to monitor the response of similar sandwich materials and glass fiber tubes during underwater blast experiments. The experiments showed that underwater blast loading caused global core crushing in sandwich panels, while air-blast loading resulted in distributed core shear failure. The results provide data to develop analytical and computational models of blast loading and highlight the importance of boundary conditions in blast-
This document summarizes a large eddy simulation of flow around a sharp-edged surface-mounted cube. The simulation was performed using the Petsc-Fem code developed at CIMEC. The flow conditions matched published benchmarks, with a Reynolds number of 40,000. An upstream channel flow was first simulated to provide turbulent inflow conditions. The simulation results are analyzed to validate the LES implementation and identify areas for improving turbulence modeling.
This document provides an introduction and table of contents to the book "Introduction to Transport Phenomena - Momentum, Heat and Mass" by Bodh Raj. The book covers momentum transfer, heat transfer, and mass transfer phenomena across four main sections. It is intended as an introductory text for undergraduate students and includes solved examples and problems for each chapter.
Experimental and Numerical Investigation of Shock/Turbulence Interaction by H...drboon
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Analysis of combustion processes in a gun ib
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ANALYSIS OF COMBUSTION PROCESSES IN A GUN
INTERIOR BALLISTICS
T. W. H. SHEU
a
& S.-M. LEE
a
a
Institute of Naval Architecture and Ocean Engineering, National Taiwan University , Taipei,
Taiwan, R.O.C
Published online: 07 Mar 2007.
To cite this article: T. W. H. SHEU & S.-M. LEE (1995) ANALYSIS OF COMBUSTION PROCESSES IN A GUN INTERIOR BALLISTICS,
International Journal of Computational Fluid Dynamics, 4:1-2, 57-71, DOI: 10.1080/10618569508904518
To link to this article: http://dx.doi.org/10.1080/10618569508904518
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ANALYSIS OF COMBUSTION PROCESSES
IN A GUN INTERIOR BALLISTICS
T. W. H. SHEU and S.-M.LEE
Institute of Naval Architecture and Ocean Engineering.
National Taiwan University. Taipei. Taiwan. R.O.C.
SUMMARY
Thispaper presents the numericalsimulationofthegas-solidcombustion physics inagun tube with a mobile
projectile by means of a flux-corrected transport nonlinear filtering scheme. Thc analysis is based on
a one-dimensional formulation of the two-phase flowfield with the space-sharing interspersed continuum
assumption. Apart from the Nobel-Abel equation or state account the interphase drag and intergranular
stress between the solid-gas phase are taken into account. The computer code has been used effectivelyto
study the pressure-wave propagation and flame dynamics in a gun barrel containing granular solid
propellants.
KEY WORDS: Gas-solid, mobile projectile, flux-corrected transport, combustion.
1. INTRODUCTION
The gun-interior ballistics involves many intricate physical and chemical processes.
Investigation of such phenomena is difficult to perform experimentally and subject to
a high degree of uncertainty and inaccuracy. Recent advances in computer hardware
and solution algorithms have made the numerical study of the two-phase gun interior
ballistics possible.
Themajor physical processes involved in a gun interior ballistics during the transient
period were well described by Kuo.' The chemical processes following the ignition of
the solid propellant usually occur within a few milliseconds. The penetration of hot
gases, produced by the combustion of the igniter near the front end of the gun barrel,
into the void region leads to the ignition of solid granules by convective heating. The
granule compaction and rapid pressurization are then set up during the subsequent
ballistic cycle.The ignition front accelerates due to the resulting pressure build-up. The
ignited propellants release hot gases which then move forward by the developed
pressure gradient and thus ignite more propellants. As a consequence, a steep presure
gradient is established inside the combustion chamber. These accelerated gaseous
products finally cause the projectile to move. The flame spreading and possible
shock-front formation in porous propellant charges are, without doubt, of importance
in the design and analysis of propellant loading and combustion chamber configur-
ation.
Numerical studies of the physics of combustion in a gun combustion chamber have
been attempted in the past two decades. Most of the computer code^^-^ were developed
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3. 58 T. W. H. SHEU AND S.-M. LEE
within the context of a one-dimensional analysis. Recently, extension to multi-dimen-
sional analysis for such problems has been made6
- S.
It is well established that the direct application of central-difference schemes to treat
steep-front waves may cause numerical oscillations in regions having strong gradients
during the ballistic cycle. The first-order accurate Lax scheme? offers positivity-
preserving monotone solutions but sacrifices the solution accuracy near the high
gradient region. Considerable numerical dissipation is added and it may sometimes
lead to erroneous predictions of the real physics. Improvements on the solution
accuracy can be easily made by using a higher-order discretization scheme, such as the
Lax-Wcndroff'scheme!", but this usually produces oscillatory solutions in regions with
now discontinuities. Accuracy and positivity seem to be contradictory to each other
and mutually exclusive. This difficulty is a crucial issue and is directly related to the
solution quality. It motivated researchers to develop a high-order non-oscillatory
solution method for capturing shock-like solutions. Historically, a large number of
high resolution schemes11-13 have been developed and successfully applied to circum-
vent the above-mentioned numerical difficulties. For a further discussion of modern
advection schemes the reader is referred to!", The present study focuses on the FCT
technique. The idea behind FCT is to combine a high-order scheme with a low-order
scheme in such a way that the high-order scheme is employed in regions where the
variables under consideration vary smoothly, whereas in regions where the variables
vary abruptly these two schemes are combined through a nonlinear combination of
diffusive and anti-diffusive fluxes. The resulting discretized equations can maintain the
positivity-preserving property.
In the following sections, a detailed theoretical formulation of the physical processes
is first given, followed by a bnef description of the FCT scheme employed. Finally, the
analysis isapplied to study the two-phase chemically reacting now in a gun combustion
chamber with a moving projectile.
2. FORMULATION
The numerical prediction of transient combustion processes in a granular-propellant
bed is made by solving the following conservation equations for a two-phase mixture.
These equations are formulated by assuming the gas and solid phases are inter-
dispersed and coupled through appropriate interactions. Each phase is treated as
a continuum. The conservation of mass, momentum, and energy for the gas and solid
phases can be represented by the following expressions:
Gas phase
Solid phase
(1)
(2)
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4. COMBUSTION PROCESSES IN A GUN 59
Table 1 Dependent variables and source terms of the gas and solid phase equations
Gus pl~rrse Solid pl~use
b st 4 s 2
Moss I filcomb 1 -
%
,
h
where Rl is the porosity of the gas and Rl +R, = 1. The dependent variables and
source terms S in the above equations are given in Table 1.
The Nobel-Abel equation is used as the equation of state for the gas phase1,
where R is the specific gas constant and b is the co-volume. The constitutive equations
used for the closure of equations ( I ) and (2) are described below.
The intergranular stress arises in a packed barrel in which the particles are agglom-
erated. This isotropic normal stress in the solid phase affects the particles only and is
determined by the following ~orrelation.~
where a is the speed of sound in the solid phase. There is no direct contact between
particles when the porosity exceeds a critical value R,.
Il~rerphnse
dray
The average steady-state interphase drag D in the momentum equations is represented
by the following correlation for a packed bed:
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5. 60 T. W. H. SHEU AND S.-M. LEE
where S = nr~ and V = 4/3 nr~ are the surface area and volume of a spherical particle,
respectively. The interphase drag per unit area F of the solid phase can be modeled by
Ergun's correlation:' 5
F = pu-upl(u-up )!
6
where
1
1.75 for R,:;:;;Rc
, [R2Rc ]
f = 1.75 R,(I _ R
c
) for R, < R, :;:;; R,
0.3 for R, < R, < I
R, = [ 1+ 0.01986C ~cRc)r'
In this study.j'is taken to be 1.4 for the sake of simplicity.
(6a)
(6b)
(6c)
Particle burning rate
An empirical pressure-dependent burning law isemployed to model the particle surface
regression rate under the steady-state condition;"
Z=Bpn
(7)
where the constant B and pressure exponent n are specified for each propellant under
investigation. The mass burning rate of propellant is given by
(8)
where 0v is the fractional rate of change in propellant-grain volume. As far as the
number of burning grains in each cell N and the number of perforations in eaeh grain
fare concerned, the propellant mass burning rate in each cell is given by
(9)
where
~ V(t) = ~(D~ - fD 2)L- ~(L-fJ(t)) [(Do - fl(t))2 - f( D; + fJ(t))2 ] (lOa)
fJ(t)=2Z~t (lOb)
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6. COMBUSTION PROCESSES IN A GUN
Gas-solid inrerphase heat transJer
The interphase heat transfer Q, arising from the propellant heating, is given by
where h, = Nukld is the total heat transfer coefficient and d = 6V/S is the equivalent
propellant grain diameter. The Nusselt number Nu is given by3.
where the dimension of pressure is MPa.
Molecular transport properties
Sutherland's law is used to compute both molecular viscosity and thermal conduc-
tivity. They are assumed to be functions of temperature and are given bys.
where
3. NUMERICAL MODEL
For the sake of simplicity in describing the presently employed discretization scheme,
equations (1) and (2), written in terms of the strong conservation law form, can be
further expressed in the following symbolic form:
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7. 62 T. W. H. SHEU AND S.-M. LEE
Apart from the nonlinearity in the above partial differential equation, it is particularly
challenging to analyze a problem involving reaction process. In the combustion
chamber, a shock-like high gradient profile over an extremely short distance may be
formed, even if the computation begins with a smooth initial condition, due to the
energy input through the release or chemical potential. Consequently is important in
the present two-phase flow simulation to adopt a discretization scheme capable or
capturing accurate but non-oscillatory solutions.
Godunov 16 has clearly demonstrated that there is no linear high-order method
which guarantees monotonieity. In this regard, it is inevitable to adopt a nonlinear
discretization method. A large number of monotone discretization methods for
equation (14), are available.':' We can divide them into three categories, namely linear
hybridization methods, methods based on Godunov's algorithm 16, total variational
diminishing (TOY) methods II. Among these, the flux corrected transport (FCT)
algorithm, classified in the first category, is the only one that is applicable to
multidimensional analysis 17. Based on the premise that the present one-dimensional
scheme can be extended to the multi-dimensional analysis, we have adopted the FCT
technique in the present analysis.
In linear hybridization, such as the FCT technique, the results ofa low-order method
and a high-order method are blended in a nonlinear fashion. We first discuss these two
basic schemes as follows:
3.1 Low-order discretization scheme
We adopt the first-order Lax method? to guarantee positivity, which is very desirable
when sharp gradients (or discontinuities) are captured as part of the solution. In the
Lax method, the solution is expanded in a Taylor series about point (x, t) only to the
first two terms and the time derivative are rearranged. This, together with the use of
centered difTerences for the remaining spatial derivatives, yields the following explicit
discretized equation
q'~+I=~[(qn+q'~ )_~(Fn -F"- )J+S~M
_J 2 _J _r l t.x -J+I _J I -J
(15)
3.2 Hiqh-order discretization method
To assure accuracy, we adopt an high-order method in smooth regions exclusively. The
Lax- Wendroffmethod I 0 was developed in the same vein as the Lax method by a Taylor
series expansion. For attaining greater accuracy, we include the second derivative term
(M 2/2)
(iJ2q/iJt 2
)lx.1in the expansion. Replacing the time derivative with the spatial
derivative through (14) yields
(16)
where the Jacobian matrix ~ is defined by d = iJDiJq.
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8. COMBUSTION PROCESSES IN A GUN 63
Using central differencing, the high-order scheme based on the Lax-Wendroff
scheme is derived to be
The Jacobian matrix at thej + 112 location is evaluated by
We denote the Lax-Wendroff solution by q**.
The first-order accurate Lax scheme is extremely diffusive to maintain positivity and
monotonicity. The second-order accurate Lax-Wendroff scheme is less diffusive but
is susceptible to instability in the vicinity of a sharp gradient. To circumvent these
problems, we incorporated a nonlinear monotone mechanism into the formulation so
that the respectiveadvantagesof the Lax and Lax-Wendroffmethods can be combined.
The flux corrected transport technique of Boris and Book13, consists of the following
steps to compute the fluxes at cell surfaces j + 112, for example, from the Lax and
Lax-Wendroff solutions.
(i) Generate diffusive fluxes:
where 5, is the diffusive coefficient defined as
(ii) Generate anti-diffusive fluxes:
where p is the anti-diffusion coefficient defined as
(iii) Limit the anti-diffusie fluxes:
To obtain a positivity-preserving algorithm, the anti-diffusive fluxes in step (ii) are
modified by a flux-correction process. The corrected fluxes are chosen in a nonlinear
manner to prevent the anti-diffusive stage from introducing new maxima or minima in
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9. 64
the solution.
where
T. W. H. SHEU AND S.-M. LEE
T= sgn(fj~1/2) (23)
DO:1/2= T· max [0, min{ T ~qj.!i/2' l[j~ 1/2 1
, nqj.:j/2}] (24)
(iv) The values of qi are given by
q a+l _ q . u _ ! ,ad +!,ad
_i - _i _i+1/2 _i-1/2
4. COMPUTED RESULTS
(25)
Projectile
In Figure I, we define the computational domain as the region between the breech and
the projectile, which is divided into 100non-uniform cells. In the course of the chamber
pressurization, the solution domain is expanded as the force acting on the projectile
exceeds the spindle force and results in the movement of the projectile. The basepad as
well as the center-core igniter normally consist of black powder. Ajet of hot gases is
discharged from a primer, taken to be 16.67% of the length ofthe chamber, to ignite the
basepad and then, in turn, ignite the center-core igniter. The ignition sequence is
modelled by specifying the flow rate and energy. In this study, a bag of M6 propellants
is considered to be uniformly distributed. The initial density of the solid propellant is
assumed to be 98.5Ibm/ft2
• The propellant ignites as its surface temperature exceeds the
ignition temperature, T,ga = 450 K~ For the sake of clarity, the input data issummarized
in Table 2.
O~;;;;--+;;;;;;;;;;:;;;;;;;;;;;;;;;;~
:..
....
....
=~~~~~~~---
IE---......,....,.....,.,..-----*-"'-"-""""---+ 16.67 ft
~~~~
i-I 2 3 4 i 98 99 100
Computational Domain
Figure I Schematic of a mobile granular propellant bed.
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10. Table 2 Input data
COMBUSTION PROCESSES IN A GUN 65
Gun Tube
Projectile
Propellant
Igniter (Black Powder)
Initial Conditions
Diameter
Breech Face
Propellant Bed
Muzzle
SurfaceTemperature
Mass
Density
Elastic Stress Wave
Total Mass
Density
Grain Length
Grain Diameter
Perforation
Burn rate
B
n
Ignition Temperature
Thermal Conductivity
Thermal Dilfusivity
Emissivity
Chemical Energy
Molecular Weight
Co-volume
Plastic Deformation Stress wave
Elastic Stress Wave
Porosity
Ultimate Failure Stress
Yield Stress
Initial Temperature
Chemical Energy
Molecular Weight
Diameter
Co-volume
Thermal Conductivity
Thermal DitTusivity
Ambient Air Temperature
Ambient Air Pressure
Propellant Bed Temperature
Velocity
0.433 ft, (constant)
O.Ocm
2.5 ft
19.I7ft
535 R
100 Ibm
500 lbm/It '
160000 ft/sec
21 Ibs
98.5Ibm/ft
0.0833 ft
0.0375 ft
0.00375 ft
Bp ern/sec
0.2218; p in M Pa
0.7864 (constant)
810 R
0.356E-4 Btu/It-see-R
0.935E-6 ft/sec
o
1607 Btu/Ibm
21.36
0.0173611 ft/lbm
1900 It/sec
3800 It/sec
0.4217 (constant)
1.584E61bf/ft
8.21E5 Ibf/ft
535 R
675 Btu/Ibm
36.13
0.00433 ft
0.016493055 (constant)
0.2E-4 Btu/ft-sec-R
1.0E-6 It/sec
535 R
2116.8Ibf/ft2
535 R
0.0 It/see
Figure 2 shows the calculated pressure distributions at various times. The initial
length of the propellant bed is 2.5 ft. Because of its highly dissipative nature the Lax
method fails to produce physically accurate solutions. The calculated pressure distri-
bution is rather uniform during the entire event; no wave propagation phenomenon is
observed. In view of this, the following discussion is based on the Lax-Wendroff
method with the FCT correction.
Owing to the penetration of the igniter gases into the propellant bed, the granular
propellants near the breach end ignite first, and their combustion products cause a
local pressure increase at t = 2 msec. The pressure wave and its associate flame
then propagate downstream to the projectile base. At this time, the projectile starts to
move since the force acting on the projectile exceeds the friction between the gun barrel
and the projectile. As time elapses, the combustion chamber volume increases because
of the movement of the projectile, thereby causing a pressure decrease starting at
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11. 66 T. W. H. SHEU AND S.-M. LEE
t = 5 msec. The computed pressure and flame fronts are presented in Figure 3, which
provide useful information regarding wave propagation in the gun tube. The calculated
gas-phase velocity distributions at various times are shown in Figure 4. According to
the pressure profiles given in Figure 2, a vigorous combustion of the granular propel-
lant occurs near the projectile base at t = 3 msec. The pressure gradient established in
the chamber causes a negative gas velocity, with combustion gases moving upstream
toward the breech end. Figure 5 presents the distributions of the solid-particle velocity.
The lag of the velocity with respect to its counterpart in the gas phase is clearly
observed.
The gas-phase temperature is also calculated, since it influences the combustion of
granular propellants. The flame spreading during the initial development of the
combustion process is clearly observed in Figure 6. The maximum temperature takes
place at the breach end at t = 3 msec. This may be attributed to the temperature
recovery effect at that (stagnation) point. The temperature distribution then becomes
more uniform as the projectile moves downstream. Figure 7 shows the calculated gas
density distributions.
Finally, the gas-phase volume fraction is calculated, giving the result shown in
Figure 8. This result serves as a guideline to examine the extent of the solid propellant
15
10
Dis/ance (f1)
(a)
5
, I
- - 3.025£-2 ms
- --oAr-- 2,000 ms
-
~ 3.000ms
-+- 4.000ms
------- 4.510 ms
---e- 5.000ms
-
- ------.e..- 5.500 ms
- v - 6.000ms
~ 6.500ms
-----B-- 9.500ms
I- -
.... -
.....
.~ -
r-"
I- -
, , ,
I.O.dO'
O.O.dO"
o
2.0.dO'
6.0xlO'
i;: 4.0x10'
.....
:.;.
::::.
~ 3.0xI0'
"'
~
0...
5.0xlO'
Figure 2 Pressure distributions in the gun barrel at various times: (a) Lax method, (2) Lax-wcndroff
method with FCT correction.
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12. COMBUSTION PROCESSES IN A GUN 67
6.0~10'
-
-
t 3.025E-2 ms
5.0~10' -2.MWmr
-3 W O m s
4.Wflms
-
-
C 4700mr
-S M W m r
G 4.0x107
-5 5 0 0 m r
;
; -6 f l W m r
-6 5 0 0 m r
s 9500mr
3.0~10'
w
w
2
4
2.0~10'
1.0x10'
0.0X1oD
0 5 10 15
Distance (
/
I
)
(b)
Figure 2 (Continued)
burning. A rapid increase ofthe gas-phase volume takes place near the forward end due
to the burning and forward motion ofthe solid particles, especially in theearly stage of
-
the ballistic cycle. It is interesting to note that in the later phase of the combustion
event, the transient compaction of the granular propellant bed near the projectile base
causes a reduction of the gas-phase volume. Finally, the gas volume fraction becomes
unity when the propellant is completely burned.
5. CONCLUSIONS
A numerical simulation of the gas-solid flowfield in a gun tube is presented in this
paper. The global trend of the combustion physics has been well predicted by the
present computer code. The main conclusions regarding the computational aspect are
summarized as follows.
I . A monotone, positivity-preserving algorithm is indispensable in predicting the
two-phase combustion in gun interior ballistics since an abrupt change in thermal as
well as flow properties may occur. A high resolution solution was made possible by
adding an anti-diKusiveflux.To maintain the positivity of the solution a limiter limiting
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13. T. W.H. SHEU AND S.-M. LEE
4
-Prn,.r< Fro",
-Flnn,.Fronr
S
.O z
*
I
" t
0
.
W 0.W2 0 . W 0.W 0.WR 0.010
Time (sec)
Figure 3 Time histories of pressure and flame fronts
5 10
Distance 01)
Figure 4 Distributions ofthe gas-phase velocity at various times
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14. COMBUSTION PROCESSES IN A GUN
Figure 5 Distributions of the solid-particle velocity at various times.
Figure 6 Distribution of the gas-phase temperature at various times.
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15. T.W. H. SHEU AND S:M. LEE
Figure 7 Distribution of the gas-phase density at various times
~ ~ " ~ ~ ~ " ~ ~ ~ ~ ~ ~ ~ ~
0 I 2 J 4 5 6 7
Distance @)
Figure8 Distribution of the gas-phase volume fraction at various !imes.
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16. COMBUSTION PROCESSES I N A G U N 71
must be incorported in the solution algorithm to ensure that no new maxima or minima
will be computed.
2. A low-order solution which must be strongly diffused to ensure positivity is
crucial to the implementation of the FCT nonlinear filtering technique.
This research was conducted under a contract sponsored by the National Science Council. Thanks are
cxpresscd lo Mr. H-CChcng, Dircctor ofthe Ballistic ResenrchCcntcr of the Combincd Service Forcc. and
his collcagueswho made this project possible.
R<fere~~ces
I. Kuo. K. K. (1986)Pri1rcip1c.sr,jCor~lhlr.stion,
John Wiley and Sons. New York.
2. Kuo. K. K., Koo, J. H.. Davis. T. R., and Coatcs, G. R. (1976) "Transient Combustion in Mobilc
G:wPermeable Propellants". Acto A.sfror~oufic.s.
3. 573-591.
3. Fisher, E. B., and Graves, K. W. (1972) "Mathematical Model of Double Base Propellant Ignition and
Combustion in thc 81 mm Mortar". Calspan Report No. GD-3029-D-I. Aug.
4. Gouh. P. S.(1977)"NumericalAnalysisofaTwo-PhascFlow with Explicit Internal Boundaries", IHCR
77-5. N:~valOrdnance Station, Indian Head. MD, April.
5. Markatos. N.C. (1986) "Modelling of Two-Phase Tritnsient Flow Combustion of Granular Propel-
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J. ~JM~~lfiph~ise
Flow, I 2 (6), 913-933.
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Propcll:rnt". ARBRL-CR-00404. July.
7. Gibeling. H. J.. Buggcln, R. C. and McDonald, H. (1980) "Dcvclopment a Two-Dimensional Implicit
Interior Ballistics Code", ARBRL-CR-0041 I.January.
8. Markatos, N.C. and Kirkcaldy. D.(1983)"Analysis and Computation ofThree-Dimensional Transient
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Phys.,
49,357-393.
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P/I.IX. l I,38-69.
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17. Lohner, R.. Morgan, K., Pcroire. J. and Vahdati, M. (1987) "Finite Elcment Flux-Corrected Transport
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Flui~is,7,1093-1 109.
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