This document summarizes the effects of nozzle shape on discharge coefficient and heat transfer. It discusses how nozzle shape, size, and internal geometry can impact the discharge coefficient and downstream flow field. Circular nozzles generally have higher discharge coefficients than non-circular nozzles. The shape and convergence of the nozzle near the exit plane also influences the uniformity of the exit velocity profile and turbulence levels, thus affecting downstream mixing and heat transfer. Non-circular nozzle shapes can cause the jet axis to switch locations, altering separation distances and heat transfer distributions on target surfaces. A variety of nozzle shapes and configurations are analyzed through experimental and analytical methods to understand these effects.

1. Discharge nozzle shape for improved
agent delivery and heat transfer
(Review article)
PRESENTED BY : SYED QASIM ZAHEER
(M12959761)
SUBMITTED TO : PROF. PETER J. DISIMILE

2. SEQUENCE
• BRIEF INTRODUCTION
• NOZZLE GEOMETRIC PARAMETERS
• NOZZLE DISCHARGE COEFFICIENT
• DISCHARGE COEFFICIENT SHAPE DEPENDENCE
• SIMPLIFIED ANALYTICAL MODEL
• EFFECT OF NOZZLE SHAPE OF CD
• EFFECT OF EXIT NOZZLE DIA OF CD
• EFFECT OF NOZZLE SHAPE ON HEAT TRANSFER
• EFFECT OF CIRCULAR NOZZLE INTERNAL GEOMETRY NEAR EXIT PLANE
• EFFECT OF NOZZLE SHAPES ON DOWNSTREAM FLOW FIELD
• AXIS SWITCHING PHENOMENON OF NON CIRCULAR NOZZLES
• EFFECT OF ORIFICE SHAPE ON FLOW FIELD AND HEAT TRANSFER
• FLOW FIELD OF TWIN AXISYMMETRIC IMPINGING JETS
• Q&A

3. BRIEF INTRODUCTION
• The discharge or spray nozzle is precision and specialized
device that allows the dispersion of fluid into spray by
atomizing the fluid i.e. converting it into droplets.
• Purpose:
◦ to distribute fluid over an area,
◦ to increase fluid surface area
◦ to create impact force on the solid surface
• Applications:
◦ watering of plants,
◦ extinguishing large or small-scale fires,
◦ deicing of aircraft wings,
◦ spray of insecticides on agriculture land,
◦ prevention of electronic cooling devices
◦ injection of fire suppressant to extinguish
fire in cluttered environment

4. BRIEF INTRODUCTION (cont’d)
• Importance - nozzle is a major factor in determining :
◦ Amount of spray applied to an area,
◦ Uniformity of application,
◦ Coverage obtained on the target surface,
◦ Amount of potential drift
• Nozzle Shape selection based on:
◦ Utility and fluid used in such devices dictates the nozzle exit shape
◦ the nozzle used in agricultural spray of insecticides are different from
those used in fire suppression
◦ Low pressure operating nozzles - agricultural sprayers
◦ fan, hollow-cone, full-cone, and others.
◦ High pressure systems - fire suppression system
◦ orifice in a pipe, a tee end, spiraling nozzles, pressure swirl nozzles etc

5. NOZZLE GEOMETRIC PARAMETERS
• Two types of jets have been used either singly or in
arrays:
◦ circular or axisymmetric jets,
◦ slot or two-dimensional jets.
• Factors Influencing Nozzle Performance
◦ nozzle shape,
◦ nozzle size and
◦ nozzle pitch,
◦ nozzle distance from surface and velocity and
◦ temperature of air jet

6. NOZZLE DISCHARGE COEFFICIENT
• Def: The nozzle discharge coefficient is defined as the ratio of
the actual mass flow rate of a gas through a nozzle to the
theoretical mass flow rate assuming no losses.
• Influencing Factors:
◦ The ratio of the actual (mean) velocity to the theoretical (ideal) velocity is
called the velocity coefficient, Cv (insignificant when nozzle length is small)
◦ The cross sectional area of the emergent jet, at the vena contracta, actually
smaller than the area of nozzle outlet. The ratio between these two areas is
often called the coefficient of contraction, CC (insignificant when nozzle
length is large)

7. NOZZLE DISCHARGE COEFFICIENT – SHAPE
DEPENDENCE
• Shape 1
◦ Nozzle shape is well rounded, the coefficient of contraction CC is almost unity,
but the coefficient of velocity CV is the important factor where friction and
therefore boundary layer effects have to be taken into consideration in any
theoretical analysis.
• Shape 8
◦ The coefficient of contraction CC plays the more important role. Here potential
(ideal fluid) flow theory is called for the coefficient of velocity CV is not significant
and boundary layer considerations are irrelevant.

8. SIMPLIFIED ANALYTICAL MODEL
• Assuming Cv = 1, Rectangular Nozzle, Reynolds number Re (=
VB/ν), Incompressible Flow

9. EFFECT OF NOZZLE SHAPE ON CD
(Const Nozzle exit dia)

10. EFFECT OF NOZZLE EXIT DIA ON CD
(Const Nozzle Shape)

11. EFFECT OF NOZZLE SHAPE ON STAGNATION
POINT HEAT TRANSFER (jet impingement case)

12. EFFECT OF NOZZLE SHAPE ON STAGNATION
POINT HEAT TRANSFER (jet impingement case)

13. Effect of geometry variation near
convergent section of circular nozzles

14. Effect of geometry variation near
convergent section of circular nozzles
• The flow characteristics and turbulence at the exit plane
of nozzle serves as initial condition for downstream flow
• The exit flow conditions desired can be:
◦ Uniform flow with low Turbulent Intensities
◦ Higher turbulent intensities for enhanced mixing
• Nozzle contraction shape is designed to attenuate the
non-uniformity at the exit plane of nozzle
• In this study effect of geometry changes near exit plane
was studied

15. Effect of geometry variation near
convergent section of circular nozzles

16. Velocity Profiles of different nozzles
geometries

17. Results along nozzle centerline

18. Results at exit plane

20. Physical problem setup

21. Heat Transfer Results at Stg point

22. TKE and Non dimensional vel profiles at
Stg point

23. Effect of Constt Re)hyd and Constt
Mass flow rate

25. Problem Setup
All polygonal orifices had same area and the
equivalent diameter, De, of these was 51 mm.
The Reynolds number, Re, was 5.0 × 104 for this
experiment using the characteristic length De,
and the characteristic velocity U0.

26. Maximum Velocity Decay and Turbulence Intensity
along the Center of the Free Jet

27. Axis Switching Phenomenon

28. Effect on separation distance on Nu profiles
at target plate due to axis switching

30. Problem Setup

31. Velocity Profiles

33. Problem Setup & results

34. Comparison 30 deg & 60 deg

35. TKE ALONG CENTERLINE

36. TI at horizontal & vertical planes

37. REFERENCES
[1] Lipp, Charles W., Practical Spray Technology: Fundamentals and
Practice, 2012, ISBN 978-0-578-10090-6
[2] Disimile, Peter. "Smart nozzle delivery system." U.S. Patent
Application No. 14/841,704.
[3] Grisso, Robert Dwight, et al. "Nozzles: selection and sizing." (2013).
[4] Yang, Jiann C., and David R. Keyser. "Fluid Dispensing and Dispersion."
Halon Options Technical Working Conferences (HOTWC). 2006
[5] Gann, Richard G. "Fire suppression system performance of alternative
agents in aircraft engine and dry bay laboratory simulations. I." National
Institute of Standards Technology, Fire Suppression System Performance
of Alternative Agents in Aircraft Engine and Dry Bay Laboratory
Simulations. I(USA), 1995, (1995): 782
[6] Etemoglu, A. B., M. K. Isman, and M. Can. "Investigation into the
effect of nozzle shape on the nozzle discharge coefficient and heat and
mass transfer characteristics of impinging air jets." Heat and mass
transfer 46.11-12 (2010): 1395-1410.

38. THANK YOU
Q & A !!!!!!!!