Critical Discharge in Actively Cooled Wing Leading Edge of a Reentry Vehicle

Abstract

The study of an innovative active cooling system of a wing leading edge of a hypersonic reentry vehicle making use of water is addressed. In particular, a steady model is developed to study the critical discharge of the cooling water into a very low-pressure ambient simulating the outlet conditions for both the reentry and wind-tunnel environments. Because of the strongly subcooled operating conditions, the model predicts no flashing within the duct connecting the outlet (hot) manifold to the vacuum ambient. The mass flow rate needed to remove the aerodynamic heat load acting on the external surface is calculated by an iterative procedure. At each iteration, for a fixed value of the mass flow rate, the pressure within the outlet manifold is calculated and the exit section critical pressure is determined as well. Subsequently, a detailed thermo-fluid-dynamic analysis is conducted to evaluate the head losses within the pipes and the peak wet wall temperature. The iteration stops when the mass flow rate guarantees noboiling conditions throughout the system. The findings arising from the steady model are confirmed by unsteady numerical simulations of the system startup.