Conditional Studies of the Wake Dynamics of Hemispherical Turret Using PSP

Abstract

Fast-response Pressure-Sensitive Paint (PSP) was used to study the wake response of the hemispherical turret at different subsonic and transonic Mach numbers to different pressure patterns on the hemisphere itself. POD technique was used to extract dominant spatial modes and the corresponding temporal coefficients of the unsteady pressure field on the hemisphere. The unsteady pressure distributions in the wake for different conditional events, such as large positive or negative temporal coefficients for different hemisphere-only POD modes, were computed and analyzed. It was found that the wake has the two main dynamic modes, the "switching" and "breathing" ones. The wake dynamics was found to be coupled with the instantaneous location of the separation line on the hemisphere. In the range of tested Mach numbers, the presence of the unsteady shock on the hemisphere did not have any significant effect of the wake dynamics.

Modal Analysis of the Surface Pressure Field Around a Hemispherical Turret using Pressure Sensitive Paint

“…A companion paper [26] uses the same experimental data to study conditional wake response to different pressure fields on the hemisphere itself to better understand the wake dynamics at high subsonic and transonic speeds.…”