Experimental and numerical studies on the performance of supersonic multi-nozzle ejector

Abstract

The nozzle number influence the performance of the supersonic ejector. To figure out the different characteristic of the supersonic multi-nozzle ejector (MNE), this paper focused on two specific MNE (single nozzle and four nozzles), compared the starting characteristics, operating characteristics, and mixing characteristics based on the experiment and numerical simulation. Results revealed that the interaction between primary total pressure and the diffuser exit pressure played a major role in determining the starting states for the MNE. The four-nozzle ejector required a higher starting pressure than the single-nozzle ejector, due to the shock loss and friction loss, meanwhile, it showed priority when the compression ratio exceeded 8 or the entrainment ratio droped to below 0.068. The non-mixing length of the four-nozzle ejector is shorter than that of the single-nozzle ejector under the same conditions, and there is a linear relationship between the non-mixing length and the entrainment ratio for the single-nozzle ejector.