Numerical Study of the Flowfield in a Differentially-Throttled Linear Aerospike

Although bell-shaped nozzle is the only type of nozzles that is practically used in every space launch vehicle, space onboard-thrusters and other proplusive devices. However, multiple alternative designs of nozzle have been studied and are considered as promising alternatives due to their increased propulsive efficiency. One of these advanced nozzles is aerospike nozzle. The winning point of the design of such nozzle is the inherent capability of its exhaust being self-adaptable to external pressure. This adaptability gives it a competitive edge over other types of nozzles. In the present numerical study, the flowfield of a linear aerospike nozzle is characterized. The nozzle plug is truncated to 20 percent of its ideal length. The Reynolds-averaged Navier-Stokes equations have been solved to predict the flowfield. The flowfield is studied in two modes of nozzle operation. The first mode is symmetric operation (non-differential throttling configuration), where the sub-nozzles on either side of the plug are subjected to the same incoming flow. In the second mode, the nozzle operates with asymmetric incoming flow conditions (differential throttling configuration); where each sub-nozzle, on either side of the plug, experiences different boundary conditions. The percent difference between the nozzle pressure ratios (NPR) of the sub-nozzles, one on each side of the plug, is termed as the differential factor (DF). For the non-differential throttling configuration, numerical simulations have been carried out for nozzle pressure ratios of 5, 50, and 200, at differential factor of 0. Whereas, for the differential throttling configuration, numerical simulations have been conducted for nozzle pressure ratios of 5, 50 and 200, but each with differential factor of 0.1, 0.25 and 0.5. The numerical results accurately characterize the flowfield around the linear aerospike nozzle in terms of Mach number contours and pressure distribution over the plug.