The supersonic ejector-diffuser system with a second throat was simulated using CFD. A fully implicit finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations and a standard k-E turbulence mo...The supersonic ejector-diffuser system with a second throat was simulated using CFD. A fully implicit finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations and a standard k-E turbulence model was used to close the governing equations. The flow field in the supersonic ejectordiffuser system was investigated by changing the ejector throat area ratio and the secondary mass flow ratio at a fixed operating pressure ratio of 10. A convergent-divergent nozzle with a design Mach number of 2.11 was selected to give the supersonic operation of the ejector-diffuser system. For the constant area mixing tube the secondary mass flow seemed not to significantly change the flow field in the ejector-diffuser systems. It was, however, found that the flow in the ejector-diffuser systems having the second throat is strongly dependent on the secondary mass flow.展开更多
In order to investigate the effectiveness of an orifice system in producing pressure drops and the effect of compressibility on the pressure drop, computations using the mass-averaged implicit Navier-Stokes equations ...In order to investigate the effectiveness of an orifice system in producing pressure drops and the effect of compressibility on the pressure drop, computations using the mass-averaged implicit Navier-Stokes equations were applied to the axisymmetric pipe flows with the operating pressure ratio from 1.5 to 20.0. The standard k- ε turbulence model was employed to close the governing equations. Numerical calculations were carried out for some combinations of the multiple orifice configurations. The present CFD data showed that the orifice systems, which have been applied to incompressible flow regime to date, could not be used for the high operating pressure ratio flows. The orifice interval did not strongly affect the total pressure drop, but the orifice area ratio more than 2.5 led to relatively high pressure drops. The total pressure drop rapidly increased in the range of the operating pressure ratio from 1.5 to 4.0, but it nearly did not increase when the operating pressure ratio was over 4.0. In the compressible pipe flows through double and triple orifice systems, the total pressure drop was largely due to shock losses.展开更多
文摘The supersonic ejector-diffuser system with a second throat was simulated using CFD. A fully implicit finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations and a standard k-E turbulence model was used to close the governing equations. The flow field in the supersonic ejectordiffuser system was investigated by changing the ejector throat area ratio and the secondary mass flow ratio at a fixed operating pressure ratio of 10. A convergent-divergent nozzle with a design Mach number of 2.11 was selected to give the supersonic operation of the ejector-diffuser system. For the constant area mixing tube the secondary mass flow seemed not to significantly change the flow field in the ejector-diffuser systems. It was, however, found that the flow in the ejector-diffuser systems having the second throat is strongly dependent on the secondary mass flow.
文摘In order to investigate the effectiveness of an orifice system in producing pressure drops and the effect of compressibility on the pressure drop, computations using the mass-averaged implicit Navier-Stokes equations were applied to the axisymmetric pipe flows with the operating pressure ratio from 1.5 to 20.0. The standard k- ε turbulence model was employed to close the governing equations. Numerical calculations were carried out for some combinations of the multiple orifice configurations. The present CFD data showed that the orifice systems, which have been applied to incompressible flow regime to date, could not be used for the high operating pressure ratio flows. The orifice interval did not strongly affect the total pressure drop, but the orifice area ratio more than 2.5 led to relatively high pressure drops. The total pressure drop rapidly increased in the range of the operating pressure ratio from 1.5 to 4.0, but it nearly did not increase when the operating pressure ratio was over 4.0. In the compressible pipe flows through double and triple orifice systems, the total pressure drop was largely due to shock losses.
