ME 814'3 T2: Compressible Flow

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ME 814.3 T2 Compressible Flow

• Instructor Maryam Einian
• Email mae345_at_mail.usask.ca
• CFD lab 1B85

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Tests

• Discharge of compressed air from a tank
• Flow through a converging-diverging nozzle

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Discharge of compressed air from a tank

• Fill the tank
• Discharge the tank
• Observe the pressure and temperature variation
  in time

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Formulation

• Quasi-steady process

• unsteady continuity
• steady energy equation

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Converging-Diverging nozzle
Application Propulsion and the High speed flow
of gases.
Mass Flow Rate Low Pressure at the
back ? More mass flow rate
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Subsonic Flow (Mlt1)
1- Nozzle isn't choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat.
4- Decelerates through the diverging section.
5- Lowering the back pressure increases the flow
speed everywhere in the nozzle.
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Sonic Flow (M1)
1- Nozzle is choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat. (M1)
4- Decelerates through the diverging section.
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Supersonic Flow (Mgt1)
1- Nozzle is choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat.
4- Accelerates through the diverging section.
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Shock Wave
1- Nozzle is choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat.
4- Accelerates through the diverging section.
5- Shock wave occurs.
6- Decelerates through the diverging section.
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Conservation
Conservation of mass
Conservation of momentum
Conservation of energy
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Isentropic Flow
A perfect gas
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Shock Wave
Highly irreversible
No isentropic process
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Mass Flow Rate
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Objectives

• To obtain the pressure distribution along a
  converging-diverging nozzle.
• To compare the experimental results with the
  theoretical calculations.

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Data Acquisition
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What Do We Require To Obtain From The Raw Data?
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Dimensions of Converging-Diverging Nozzle
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A Summary of Important Quantities
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