Investigation of the flow structure on a small-scale gas-dynamic setup: identification of the secondary flow in the case of exhaustion of a clustered supersonic jet into a rarefied space

A possibility of using small-scale vacuum setups for experimental investigations of supersonic jets escaping from supersonic nozzles into vacuum or a rarefied space is considered. Results of studying the structure of the secondary supersonic flow formed in supersonic jets with developed condensation, which is detected for the first time, are reported. The present investigations are carried out with the use of photometry and spectrometry of jets with the use of emission excited by an electron beam; flow visualization is also performed. The results obtained in the study are analyzed; capabilities and specific features of various methods of flow registration are considered. An empirical model, which establishes the dependence between the detected secondary flow and the process of formation of large clusters in the flow, is developed and justified.