The document discusses key concepts related to fluid flow discharge including flow through orifices and mouthpieces, Torricelli's theorem, theories of small and large orifice discharge, notches and weirs, and the power of a fluid stream. Examples are provided to demonstrate calculating discharge from an orifice, theoretical discharge through a sluice gate, and estimating electric power output from a hydroelectric plant based on water flow rate and losses.
This ppt is more useful for Civil Engineering students.
I have prepared this ppt during my college days as a part of semester evaluation . Hope this will help to current civil students for their ppt presentations and in many more activities as a part of their semester assessments.
I have prepared this ppt as per the syllabus concerned in the particular topic of the subject, so one can directly use it just by editing their names.
These slides will help you understand the concept of Specific Energy Curves including Critical depth, Critical velocity, Condition of minimum specific energy, and Condition for maximum discharge.
This ppt is more useful for Civil Engineering students.
I have prepared this ppt during my college days as a part of semester evaluation . Hope this will help to current civil students for their ppt presentations and in many more activities as a part of their semester assessments.
I have prepared this ppt as per the syllabus concerned in the particular topic of the subject, so one can directly use it just by editing their names.
These slides will help you understand the concept of Specific Energy Curves including Critical depth, Critical velocity, Condition of minimum specific energy, and Condition for maximum discharge.
The second law of thermodynamics is explored in this lecture. Topics covered include:
Introduction to the second law
Thermal energy reservoirs
Heat engines
Thermal efficiency
The 2nd law: Kelvin-Planck statement
Refrigerators and heat pumps
Coefficient of performance (COP)
The 2nd law: Clasius statement
Perpetual motion machines
Reversible and irreversible processes
Irreversibility's, Internal and externally reversible processes
The Carnot cycle
The reversed Carnot cycle
The Carnot principles
The thermodynamic temperature scale
The Carnot heat engine
The quality of energy
The Carnot refrigerator and heat pump
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Conservation of mass
Mass and volume flow rates
Mass balance for a steady flow process
Mass balance for incompressible flow
Flow work and the energy of a flowing fluid
his lecture examines both work and energy in closed systems and categorises the different types of closed systems that will be encountered.
Moving boundary work
Boundary work for an isothermal process
Boundary work for a constant-pressure process
Boundary work for a polytropic process
Energy balance for closed systems
Energy balance for a constant-pressure expansion or compression process
Specific heats
Constant-pressure specific heat, cp
Constant-volume specific heat, cv
Internal energy, enthalpy and specific heats of ideal gases
Energy balance for a constant-pressure expansion or compression process
Internal energy, enthalpy and specific heats of incompressible substances (Solids and liquids)
Identifying the correct properties of a substance is of vital importance. Many of these properties are distilled from property tables. This lecture addresses how to identify these properties.
Pure substance
Phases of a pure substance
Phase change processes of pure substances
Compressed liquid, Saturated liquid, Saturated vapor, Superheated vapor Saturated temperature and Satuated pressure
Property diagrams for phase change processes
The T-v diagram, The P-v diagram, The P-T diagram, The P-v-T diagram
Property tables
Enthalpy
Saturated liquid, Saturated vapor, Saturated liquid vapor mixture, Superheated vapor, compressed liquid
Reference state and Reference values
The ideal gas equation of state
Is water vapor an ideal gas?
Lecture covering the basic concepts required for the module:
Systems and control volumes
Properties of a system
Density and specific gravity
State and equilibrium
The state postulate
Processes and cycles
The state-flow process
Temperature and the zeroth law of thermodynamics
Temperature scales
Pressure
Variation of pressure with depths
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Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
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http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
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This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
2. KV
Identify the unique vocabulary used in the description and
analysis of fluid flow with an emphasis on fluid discharge
Describe and discuss how fluid flow discharge devices
affects fluid flow.
Derive and apply the governing equations associated with
fluid discharge
Determine the power of flow in a channel or a stream and
how this can be affected by height, pressure, and/or
geometrical properties.
OBJECTIVE
S
3. KV
FLOW THROUGH
ORIFICES and
MOUTHPIECES
An orifice
Is an opening having a closed perimeter
A mouthpiece
Is a short tube of length not more than two to
three times its diameter
5. KV
TORRICELLI’s
THEOREM
Torricelli’s theorem states that the velocity of the
discharging jet is proportional to the square root of the
head producing flow. This is support by the preceding
derivation;
The discharging flow rate can be determined theoretically
if A is the cross-sectional area of the orifice
Actual discharge
6. KV
The velocity of the jet is less than that determined by the velocity of jet equ because
there is a loss of energy between stations ① and ② i.e
actual velocity, u = Cu √(2gH)
where Cu is a coefficient of velocity which is determined experimentally and is of the
order 0.97 - 0.98
The paths of the particles of the fluid converge on
the orifice and the area of the discharging jet at B
is less than the area of the orifice A at C
actual area of jet at B = Cc A
where Cc is the coefficient of contraction -
determined experimentally - typically 0.64
Vena contracta
C B
pB
u
uC
pC
7. KV
Actual discharge = Actual area at B × Actual velocity at B
we see that the relationship between the coefficients is Cd = Cc × Cu
To determine the coefficient of discharge measure the actual discharged volume
from the orifice in a given time and compare with the theoretical discharge.
8. KV
(a) A jet of water discharges horizontally into the atmosphere from an orifice in
the side of large open topped tank. Derive an expression for the actual
velocity, u of a jet at the vena contracta if the jet falls a distance y vertically for
a horizontal distance x, measured from the vena contracta.
(b) If the head of water above the orifice is H, calculate the coefficient of velocity.
(c) If the orifice has an area of 650 mm2 and the jet falls a distance y of 0.5 m in a
horizontal distance x of 1.5 m from the vena contracta, calculate the values of
the coefficients of velocity, discharge and contraction, given that the
volumetric flow is 0.117 m3/min and the head H above the orifice is 1.2 m
EXAMPLE 1
9. KV
Let t be the time taken for a particle of fluid to travel from the vena contracta
A to the point B.
12. KV
(a) A reservoir discharges through a sluice gate of width B and height D. The
top and bottom openings are a depths of H1 and H2 respectively below
the free surface. Derive a formula for the theoretical discharge through
the opening
(b) If the top of the opening is 0.4 m below the water level and the opening is
0.7 m wide and 1.5 m in height, calculate the theoretical discharge (in
meters per second) assuming that the bottom of the opening is above the
downstream water level.
(c) What would be the percentage error if the opening were to be treated as
a small orifice?
EXAMPLE 2
13. KV
Given that the velocity of flow will be greater at the bottom than at
the top of the opening, consider a horizontal strip across the
opening of height δh at a depth h below the free surface
For the whole opening, integrating from h = H1 to h = H2
16. KV
Consider a horizontal strip of width b and height δh at a depth h below the
free surface.
Integrating from h = 0 at the free surface to h = H at the bottom of the notch
b must be expressed in terms of h before integrating
17. KV
For a rectangular notch, put b = constant = B
b = constant
B
H
For a vee notch with an included angle θ, put b
= 2(H - h)tan(θ⁄2)
b = 2(H - h)tan(θ⁄2)
H
h
θ
18. KV
In the foregoing analysis it has been assumed that
• the velocity of the liquid approaching the notch is very small so that its
kinetic energy can be neglected
• the velocity through any horizontal element across the notch will depend
only on the depth below the free surface
These assumptions are appropriate for flow over a notch or a weir in the side of
a large reservoir
If the notch or weir is located at the end of a narrow channel, the velocity of
approach will be substantial and the head h producing flow will be increased by
the kinetic energy;
where ū is the mean velocity and α is the kinetic energy correction factor to
allow for the non-uniform velocity over the cross section of the channel
19. KV
Therefore
at the free surface, h = 0 and x = αū2/2g, while at the sill , h = H and
x = H + αū2/2g. Integrating between these two limits
For a rectangular notch, putting b = B = constant
20. KV
Pressure, p, velocity, u, and elevation, z, can cause a stream of fluid to do
work. The total energy per unit weight H of a fluid is given by
If the weight per unit time of fluid is known, the power of the stream can be
calculated;
THE POWER OF
A STREAM OF
FLUID
23. KV
In a hydroelectric power plant, 100 m3
/s of water flows from an elevation of
12 m to a turbine, where electric power is generated. The total irreversible
heat loss is in the piping system from point 1 to point 2 (excluding the
turbine unit) is determined to be 35 m. If the overall efficiency of the turbine-
generator is 80%, estimate the electric power output.
EXAMPLE 3
24. KV
Assumptions
1.The flow is steady and incompressible
2.Water levels at the reservoir and the discharge
site remain constant
Properties
We take the density of water to be 1000 kg/m3
The mass flow rate of water through the turbine is
We take point ➁ as the reference level, and thus z2 = 0. Therefore the
energy equation is
(Çengel, et al 2008)
25. KV
Also, both points ➀ and ➁ are open to the atmosphere (P1 = P2 = Patm) and the
flow velocities are negligible at both points (V1 = V2 = 0). Then the energy
equation for steady, incompressible flow reduces to
Substituting, the extracted turbine head and the corresponding turbine power
are
Therefore, a perfect turbine-generator would generate 83,400 kW of electricity
from this resource. The electric power generated by the actual unit is
Note that the power generation would increase by almost 1 MW for each
percentage point improvement in the efficiency of the turbine-generator unit.
26. KV
Flow through orifices and mouthpieces
Theory of small orifice discharge
Torricelli’s theorem
Theory of large orifices
Notches and weirs
The power of a stream of fluid
27. KV
Andrews, J., Jelley, N., (2007) Energy science: principles, technologies
and impacts, Oxford University Press
Bacon, D., Stephens, R. (1990) Mechanical Technology, second edition,
Butterworth Heinemann
Boyle, G. (2004) Renewable Energy: Power for a sustainable future,
second edition, Oxford University Press
Çengel, Y., Turner, R., Cimbala, J. (2008) Fundamentals of thermal fluid
sciences, Third edition, McGraw Hill
Douglas, J.F., Gasoriek, J.M., Swaffield, J., Jack, L. (2011), Fluid
Mechanics, sisth edition, Prentice Hall
Turns, S. (2006) Thermal fluid sciences: An integrated approach,
Cambridge University Press
Young, D., Munson, B., Okiishi, T., Huebsch, W., 2011Introduction to
Fluid Mechanics, Fifth edition, John Wiley & Sons, Inc.
Some illustrations taken from Fundamentals of thermal fluid sciences
Editor's Notes
To appreciate energy conversion such as hydro, wave, tidal and wind power a detailed knowledge of fluid mechanics is essential.
During the course of this lecture, a brief summary of the basic physical properties of fluids is provided and the conservation laws of mass and energy for an ideal (or inviscid) fluid are derived.
The application of the conservation laws to situations of practical interest are also explored to illustrate how useful information about the flow can be derived.
Finally, the effect of viscosity on the motion of a fluid around an immersed body (such as a turbine blade) and how the flow determines the forces acting on the body of interest.
Orifices and mouthpieces can be used to measure flow rate.
An orifice is an opening which has a closed perimeter. They are generally made in the walls or the bottom of a tank containing fluid and as a consequence the contents can flow through opening thereby discharging. Orifice’s may be classified by size, shape, shape of the upstream edges and the conditions of discharge.
A mouthpiece is a tube not more than two to three times its diameter. Such would be fitted to a circular opening or orifice of the same diameter of a tank thereby creating an extension of the orifice. The contents of the tank could be discharged through this.
An orifice is an opening found in the base or side of a tank. The pressure acting on the fluid surface forces a discharge through this opening, therefore the volumetric flow rate discharged will depend on the the head of fluid above the level of the opening. The term “small orifice” is used when the opening is small compared to the head producing flow, i.e. it can be assume that this head does not vary appreciably from point to point across the orifice.
A small orifice in the side of a large tank is with a free surface open to the atmosphere is illustrated. At point on the free surface ① the pressure is atmospheric pressure p1. As the large, the velocity u1 can be considered to be negligible. The conditions in the region of the Orifice are uncertain, but at a point ② in the jet, the pressure p2 will again be atmospheric pressure with a velocity u2 which equals the jet velocity u. Establishing the datum for potential energy at the centre of the orifice and applying Bernoulli’s equ (assuming no loss in energy)
u = √(2gH) can be applied to compressible or non-compressible fluids. H is expressed as the head of the fluid flowing through the orifice (H = p/ρg)
The actual discharge is considerably less than the theoretical discharge therefore a coefficient of discharge must be introduced Cd
There are two reasons for the difference between the theoretical and actual. What are these?
The velocity of the jet is less than that determined by the velocity of jet equ because there is a loss of energy between stations ① and ② i.e actual velocity = Cu √(2gH) where Cu is a coefficient of velocity which is determined experimentally and is of the order 0.97 - 0.98
In the plane of the of the orifice the streamlines have a component of velocity towards the centre and the pressure at C is greater than atmospheric pressure. At B, a small distance outside the orifice, the streamlines have become parallel. This section through B is referred to as the vena contracta
The values of the coefficient of discharge, coefficient of velocity and the coefficient of contraction are determined experimentally.
If the orifice is not in the bottom of the tank, then to determine measure the actual velocity, the jet’s profile must be measured.
If orifice has a large opening compared to the head producing flow, then the discharge calculated using the formula for a small orifice and the head measured from the centre line of the orifice will yield an inaccurate result, i.e. the velocity will vary substantially from top to bottom.
There for a large orifice the preferred method to is calculate the flow through a thin horizontal strip across the orifice opening an integrate from top to bottom in order to determine the theoretical discharge. From this the actual discharge can be determined providing the coefficient of discharge is known.
An opening in the side of a tank or a reservoir which extends above the free surface is referred to as a Notch. It is essentially a large orifice which does not have an upper edge and therefore has a variable area depending upon the level of the free surface.
A weir is a notch on much larger scale i.e. it may have a large width in the direction of flow.
The method developed for determining the theoretical flow through a large orifice is also used to determine the theoretical flow for a notch.
This theory applies to a notch of any shape.
NOTE - the value of ū is obtained by dividing the discharge by the full cross-sectional area of the channel (not the notch).
NOTE - the value of ū is obtained by dividing the discharge by the full cross-sectional area of the channel (not the notch).