ME T2: Compressible Flow Instructor: Maryam Einian CFD lab: 1B85 1
Tests 1. Discharge of compressed air from a tank 2. Flow through a converging-diverging nozzle 2
Discharge of compressed air from a tank Fill the tank Discharge the tank Observe the pressure and temperature variation in time 3
Formulation Quasi-steady process: unsteady continuity steady energy equation
Converging-Diverging nozzle 5 Application: Propulsion and the High speed flow of gases. Mass Flow Rate: Low Pressure at the back ? More mass flow rate
Subsonic Flow (M<1) 6 1- Nozzle isn't choked 2- Accelerates through the converging section 3- Reaches its maximum speed at the throat. 5- Lowering the back pressure increases the flow speed everywhere in the nozzle. 4- Decelerates through the diverging section.
Sonic Flow (M=1) 7 1- Nozzle is choked 2- Accelerates through the converging section 3- Reaches its maximum speed at the throat. (M=1) 4- Decelerates through the diverging section.
Supersonic Flow (M>1) 8 1- Nozzle is choked 2- Accelerates through the converging section 3- Reaches its maximum speed at the throat. 4- Accelerates through the diverging section.
Shock Wave 9 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.
Conservation 10 Conservation of mass Conservation of energy Conservation of momentum
Isentropic Flow 11 A perfect gas
Shock Wave 12 Highly irreversibleNo isentropic process
13 Mass Flow Rate
Objectives To obtain the pressure distribution along a converging-diverging nozzle. To compare the experimental results with the theoretical calculations. 14
SupersonicShock waveSubsonic P os =; P tank =, P b =; T o = xPressure, P s x x 15 Data Acquisition
What Do We Require To Obtain From The Raw Data? 16
17 Dimensions of Converging-Diverging Nozzle
A Summary of Important Quantities R12.70 mm0.500 in DtDt mm0.582 in D probe 1.50 mm0.059 in P atm To be measured k1.40 R air 287 J/KgK1717 ft 2 /s 2o R 18
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