Base Flow Characterization of Clustered Linear Aerospike Nozzles in the Presence of External Flow

摘要

Base wake behaviors of an aerospike nozzle under the presence of external flow were characterized by surface pressure measurements, flow visualizations using the background oriented Schlieren method, and theoretical modeling. The test model consisted of three clustered cell nozzle modules or a nonclustered two-dimensional nozzle with a designed Mach number of 3.5, followed by a straight section and an ideal contoured spike. Additionally base blocks which have 60°, 75°, and 90° inclined against the flow direction were used to investigate the relationship among base angles, depth, and pressure distributions. The model was exposed to an external flow of Mach 2.0 to simulate off-design transonic flight conditions. Results of flow visualizations and pressure measurements showed that the base pressure can be higher than the environmental pressure level under the presence of external flow with the base angle of 60° case. The tendency is stronger when the base depth is shallower. The physics-based model predicted the measured base pressure distribution better than the previous model.