Unsteady simulation of frontal cavity in supersonic flows

Abstract

This study is focused to develop the understanding of bow-shock instability observed around a frontal hemispherical shell in supersonic flow through numerical simulations. The frontal bow shock instability is observed in many situations such as canopy of supersonic decelerators, wind tunnel testing of rigid concave hemispherical shell in supersonic and hypersonic flows. In previous numerical studies, the small amplitude fluctuations of bow shock in front of hemispherical shell are well captured, but rapid large amplitude fluctuation in bow shock has caused failure in simulation. Hence, the principal objective and novelty of the study is to capture and analyse the experimentally observed ‘large amplitude’ shock unsteadiness in front of hemispherical shell in a supersonic flow of Mach 4 using the recently emerging numerical concept of Detached Eddy Simulations (DES).