Aerospike nozzles propose several benefits over conventional convergent-divergent nozzles due to their altitude-compensating effects.Herein,as a part of the design optimization study,computational simulations are perf...Aerospike nozzles propose several benefits over conventional convergent-divergent nozzles due to their altitude-compensating effects.Herein,as a part of the design optimization study,computational simulations are performed on conical aerospike nozzles for a wide range(1.8<NPR<10)of operating conditions.Numerical studies have been carried out using a validated two-dimensional axisymmetric,an implicit Reynolds-averaged Navier-Stokes equations(RANS)solverwith a single equation Spalart-Allmaras turbulence model.At different nozzle pressure ratio(NPR),static pressures on the aerospike surface are estimated and compared for different cowl extensions.Mach number contours and their shadowgraphs are used to visualize the flow structure at different NPR for different cowl length extensions.It is observed that a minor alteration of cowl length extension leads to significant variations on the pressure distribution on the surface of the spike at low NPRs(<3.12).In addition,marginal variations were noticed on intermediate cases(3.12<NPR<8.5).No significant effect was noticed for the cases with high NPR(>8.5).At lower NPR,flow separation occurs at the spike surface as well as on the cowl for larger cowl extensions,so it behaves like a convergent-divergent nozzle,whereas it occurs on the spike for higher NPR.It is concluded that the design optimization of cowl length extension at various NPRs is inevitable for achieving the highest momentum thrust while compensating the altitude using conical aerospike nozzles.展开更多
文摘Aerospike nozzles propose several benefits over conventional convergent-divergent nozzles due to their altitude-compensating effects.Herein,as a part of the design optimization study,computational simulations are performed on conical aerospike nozzles for a wide range(1.8<NPR<10)of operating conditions.Numerical studies have been carried out using a validated two-dimensional axisymmetric,an implicit Reynolds-averaged Navier-Stokes equations(RANS)solverwith a single equation Spalart-Allmaras turbulence model.At different nozzle pressure ratio(NPR),static pressures on the aerospike surface are estimated and compared for different cowl extensions.Mach number contours and their shadowgraphs are used to visualize the flow structure at different NPR for different cowl length extensions.It is observed that a minor alteration of cowl length extension leads to significant variations on the pressure distribution on the surface of the spike at low NPRs(<3.12).In addition,marginal variations were noticed on intermediate cases(3.12<NPR<8.5).No significant effect was noticed for the cases with high NPR(>8.5).At lower NPR,flow separation occurs at the spike surface as well as on the cowl for larger cowl extensions,so it behaves like a convergent-divergent nozzle,whereas it occurs on the spike for higher NPR.It is concluded that the design optimization of cowl length extension at various NPRs is inevitable for achieving the highest momentum thrust while compensating the altitude using conical aerospike nozzles.
