The Primitive Thought and Its Impinge on the Settlement Layout
Presentation on Nozzle and Diffuser and... · 2020. 4. 27. · •Steam, water and gas turbines to...
Transcript of Presentation on Nozzle and Diffuser and... · 2020. 4. 27. · •Steam, water and gas turbines to...
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Presentation on
Nozzle and Diffuser
Presented by:
Prof. Prabha Chand
NIT Jamshedpur
Department of Mechanical Engineering
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Introduction
• A nozzle is a passage of smoothly varying cross- section by means of which the pressure energy of working fluid is converted into kinetic energy.
Applications
• Steam, water and gas turbines to produce high velocity jet to impinge on curved blades for driving turbine shaft
• Rocket motors and jet engine to produce thrust
• Flow measurements
• Artificial foundations
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Types of nozzles
• Converging nozzle
• Diverging nozzle
• Converging -Diverging nozzle
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Types of diffusers
(a) Direction of flow
i. axial diffusers
ii. Radial diffusers
(b) Nature of flow
i. Subsonic diffusers
ii. Supersonic diffusers
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Equation of continuity.
According to continuity equation
The continuity equation may be expressed in differential form.
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Sonic velocity :- the expression for sonic velocity is derived by considering the propagation of a pressure wave is an isentropic flow through a pipe of uniform cross-section which is given by
For an ideal gas,
Mach Number:-
M=1, for sonic flow
M<1, for subsonic flow
M>1, for supersonic flow
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Stagnation properties
• Stagnation properties of fluid are those properties reached at a point where the velocity is brought to zero isentropically.
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The steady flow energy equation in nozzles
Energy entering into nozzle=energy leaving the nozzle
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Potential energy is negligible z1 = z2 , there is no heat supplied and no mechanical work done by apparatus.
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The momentum equation for the flow through steam nozzle
For SFEE
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Nozzle Efficiency
• Nozzle efficiency is define as the ratio of actual heat drop to that due to isentropic expansion
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• For gas Nozzles
• Coefficient of discharge may be define as the ratio of actual mass flow rate to that due to isentropic expansion.
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Effect of friction on the velocity of steam leaving the nozzle.
• Consider the flow of steam with friction through a nozzle. The actual heat drop will be
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Adiabatic flow through diffuser
SFEE to a diffuser under isentropic flow condition
For isentropic flow enthalpy remains constant and there is no change of entropy and loss of stagnation pressure
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Diffuser Efficiency
• Is define as the ratio of isentropic enthalpy rise to the actual enthalpy rise in a diffuser
• For incompressible flow and isentropic process
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Total Pressure Loss Coefficient
• The total pressure loss coefficient is define as the ratio of decrease in total pressure to initial kinetic energy.
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Pressure recovery coefficient • Pressure recovery coefficient is define as the ratio of static pressure rise
to initial kinetic energy.
continuity equation for incompressible flow yield
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Mass of discharge through nozzle
p-v diagram for isentropic expansion in nozzle
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The mass of steam in kg per second flowing through a nozzle under a pressure drop from p1 to p2