Experiments with Ejector Rocket Entrainment

摘要

Experimental tests are conducted to evaluate the effect of an annular rocket exhaust pattern on the mixing characteristics of a simple ejector. Rocket exhaust is simulated using pure oxygen while air is entrained from the surroundings at static conditions. Results are compared with an equivalent configuration using traditional circular rocket exhaust nozzles. It is shown that an annular rocket exhaust pattern yields a ratio of entrained air to rocket mass flows over 75 % higher than an equivalent circular rocket exhaust pattern over a range of rocket chamber total pressures. It is demonstrated that an annular rocket exhaust pattern within a straight ejector duct with a length-to-diameter ratio of 6 is able to produce entrained air to rocket mass flow ratios up to 10 % higher than a straight then expanding ejector configuration twice as long employing a circular rocket exhaust pattern. Exit plane measurements of both total pressure and oxygen concentration are also collected at high and low rocket chamber total pressures. An annular exhaust pattern is shown to yield an average Mach number between 20 and 30% higher than an equivalent configuration using a circular exhaust pattern. Oxygen concentration results indicate that an annular rocket exhaust pattern is better able to mix the entrained air and rocket streams through a more uniform concentration distribution and smaller regions of distinct air and/or rocket species.