Side-Force Amplification on an Aerodynamically Thrust-Vectored Aerospike Nozzle

Abstract

Results from computational and coldow experiments on uidic thrust vectoring of a small-scale aerospike thruster are presented. Thrust vectoring is produced by injection of a secondary uid into the primary ow eld normal to the nozzle axis. The experimental aerospike nozzle was truncated at 57% of its full theoretical length. For these tests, carbon dioxide is the working uid. Injection points near the end of the truncated spike produced the highest force ampli cation factors. Explanations are given for this phenomenon. For secondary injection near the end of the aerospike, side force ampli cation factors up to 1.4 and side force speci c impulses up to 55 s were demonstrated. By comparison, the main ow speci c impulse averaged approximately 38s. Secondary side-injection pulses were observed to crisply reproduce side forces with a high degree of delity. Side force levels approach 2.7% of the total thrust level at maximum e ciency. Higher side forces of 4.7% axial thrust were also achieved at reduced e ciency. The side force ampli cation factors were independent of operating nozzle pressure ratio for the range of chamber pressures evaluated in this test series.