Journal Article

Instabilities of Transonic Turbulent Flow over a Flat-Sided Wedge

Kuzmin, A

2023

Overview

The transonic turbulent two-dimensional airflow over a symmetric flat-sided double wedge is studied numerically. Solutions of the Reynolds-averaged Navier-Stokes equations are obtained with ANSYS-18.2 CFX finite-volume solver of second order accuracy on a fine mesh. The solutions demonstrate an extreme sensitivity of the flow field and lift coefficient to variation of the angle of attack α or free-stream Mach number M∞. Non-unique flow regimes and hysteresis in certain bands of α and M∞ are identified. Interaction of shock waves and local supersonic regions is discussed. The study confirms a concept of shock wave instability due to a coalescence/rupture of supersonic regions. In addition to the instability of shock wave locations, the numerical simulation shows a buffet onset, i.e., self-exciting oscillations due to instability of a boundary layer separation at the rear of wedge. Curious flow regimes with positive lift at negative angles α and, vice versa, with negative lift at positive angles α, are pointed out. A piecewise continuous dependence of the lift coefficient on two free-stream parameters, α and M∞, is discussed.

• Publisher: Isfahan University of Technology
• Subject: Aerodynamic coefficients / Air flow / Angle of attack / Boundary layer stability / Boundary layers / boundary-layer separation / Coalescence / Flow separation / Flow velocity / Free flow / Heat / Instability / interaction / local supersonic regions / Mach number / Mathematical models / Negative lift / Numerical analysis / Oscillations / Reynolds averaged Navier-Stokes method / Reynolds number / Shock waves / Transonic flow / Turbulence models / Turbulent flow / Two dimensional flow