240 likes | 717 Vues
ME 814.3 T2: Compressible Flow. Instructor: Maryam Einian Email: mae345@mail.usask.ca CFD lab: 1B85. Tests. Discharge of compressed air from a tank Flow through a converging-diverging nozzle. Discharge of compressed air from a tank. Fill the tank Discharge the tank
E N D
ME 814.3 T2: Compressible Flow Instructor: Maryam Einian Email: mae345@mail.usask.ca CFD lab: 1B85
Tests • Discharge of compressed air from a tank • Flow through a converging-diverging nozzle
Discharge of compressed air from a tank • Fill the tank • Discharge the tank Observe the pressure and temperature variation in time
Formulation • Quasi-steady process: • unsteady continuity • steady energy equation
Converging-Diverging nozzle 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) 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.
Sonic Flow (M=1) 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) 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 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 Conservation of mass Conservation of momentum Conservation of energy
Isentropic Flow A perfect gas
Shock Wave Highly irreversible No isentropic process
Objectives • To obtain the pressure distribution along a converging-diverging nozzle. • To compare the experimental results with the theoretical calculations.