Effect of significant acceleration and deceleration on boundary layer properties of a laminar flat plate

Significant acceleration and deceleration for magnitudes of the orders of 1000g occur frequently for manoeuvring ballistic projectiles. However, there are few studies in the open literature that investigate the accelerating aerodynamics for the high Mach number flow regime where unsteady peak surface pressures and temperatures can have a significant impact on the vehicle. The present study is aimed at investigating the effect of significant acceleration and deceleration on the boundary layer for a flat plate in constant linear acceleration in the hypersonic regime. Unsteady numerical simulations are carried out in an open source customised solver ARFrhoPimpleFoam that operates fully in the body fixed non-inertial frame. In the acceleration event, the flat plate is accelerated from steady state conditions at Mach 4 to Mach 7 at 1000g,10000g and 100000g. In the deceleration event, the flat plate is decelerated from steady state conditions at Mach 7 to Mach 4 at −1000g,−10000g and −100000g. Acceleration through the hypersonic regime resulted in cooling of the flat plate, resulting in an increase in the skin friction coefficient when compared to the same instantaneous Mach numbers for the 100000g magnitude. Deceleration through the hypersonic regime resulted in heating of the flat plate, resulting in an decrease in the skin friction coefficient when compared to the same instantaneous Mach numbers for the −100000g magnitude. No significant changes were observed for both acceleration and deceleration through the hypersonic regime for magnitudes 1000g,10000g, −1000g and −10000g. The present results are explained using the concept of flow history