Instability of the shock wave/ sonic surface interaction

TL;DR

This paper investigates the instability phenomena in transonic turbulent flows, revealing how small perturbations can cause abrupt shock position changes due to sonic surface instability.

Contribution

It provides numerical evidence of shock and sonic surface instability in 2D and 3D transonic flows using high-resolution RANS simulations.

Findings

Existence of adverse Mach numbers causing shock position jumps

Instability of sonic surface and shock wave interaction

Abrupt shock shifts due to flow perturbations

Abstract

The work addresses 2D and 3D turbulent transonic flows past a wall with an expansion corner. A curved shock wave is formed upstream of a cylinder located above the corner. Numerical solutions of the Reynolds-averaged Navier-Stokes equations are obtained on fine meshes with a finite-volume solver of the second order accuracy. The solutions demonstrate the existence of adverse free-stream Mach numbers which admit abrupt changes of the shock position at small perturbations. This is explained by an instability of the closely spaced sonic surface and shock wave on the wall.