Significance of dynamic control on suddenly expanded flow when nozzles are over, under, and perfectly expanded

In this paper, investigations are carried out to quantify the usefulness of the flow control in the recirculation and the growth of the flow in the tube at supersonic Mach numbers for pipe diameter 18 mm. Only those cases are shown when there is an effect of the flow control management on the stream pattern. Mach numbers of study are 1.87, 2.2, and 2.58 at various expansion levels for duct sizes 2D, 4D, 6D, and 10D. For the highest duct lengths, 6D and 10D flow fields of the duct turn oscillatory and control reversal phenomena are observed. For short ducts 1D and 2D, no such phenomena are seen. When nozzles face under-expanded or over-expanded flow at Mach 1.87 and 2.2, the flow control management does not give the needed outcomes and results in decreased pressure. Also, it is seen that at Mach 2.58, nozzles remain over-expanded, and when control is used, they end up in a rise of pressure of the tube. The minimum duct size requirement for the first two Mach is 1D, and for the highest Mach of the study, it is 3D. (c) 2021 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the Global Conference on Recent Advances in Sustainable Materials 2021.

Automated summary

In this paper, the usefulness of flow control in recirculation and flow growth in a supersonic tube is quantified for different levels of expansion and tube lengths. The results show that flow control management has an effect on the flow pattern, with oscillatory flow fields and control reversal phenomena observed in longer ducts. However, for shorter ducts, no such phenomena are seen. The study also finds that flow control has different outcomes at different Mach numbers, with pressure decrease and increase observed in under-expanded and over-expanded flow, respectively.