Bo Sun This email address is being protected from spambots. You need JavaScript enabled to view it.1 and Zhuo Chang-fei1

1Department of Aerospace Engineering, Nanjing University of Science and Technology, China P.R.C


Received: August 19, 2019
Accepted: January 6, 2020
Publication Date: June 1, 2020

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The typical features of asymmetric flow in supersonic ducts and Coanda effect which attaches a jet to an adjacent solid surface are summarized. Based on these similar features and six typical flow patterns in nozzles, the Coanda effect is employed to analyze the asymmetric SBLI (Shock/Boundary Layer Interactions) qualitatively and allows to give a preliminarily reasonable explanation. The evolution roadmap of flow pattern in 2-D ramp and axisymmetric nozzles is summed up. The results show that the entrainment of mainstream shear layer on separation flow caused by SBLI should be the predominant reason for flow asymmetry, which is the manifestation of Coanda effect in confined SBLI. Flow asymmetry will disappear when the Coanda effect breaks down due to strong SBLI causing large separations. When asymmetric SBLI appears, two flow patterns are possible: one has Restricted Shock Separation (RSS) on both sides; the other one has RSS on one side and Free Shock Separation (FSS) on the other side. Asymmetry flipping in nozzle flow experiments from one run to the next is a result of randomicity of the Coanda effect. The flow pattern with RSS on both sides and high confinement level maybe a probable cause for asymmetry flipping unsteadiness in one test run.

Keywords: Asymmetry; Shock/Boundary Layer Interactions; Coanda effect



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