Numerical study on the effect of moist air non-equilibrium condensation on the aerodynamic performance of a supersonic airfoil

The effect of non-equilibrium condensation in moist air on the aerodynamic performance of supersonic airfoils is a critical issue in the design of hypersonic vehicles. In this study, numerical simulation of non-equilibrium condensation in moist air was performed using a modified model in Fluent and validated with experimental data. The effects of humidity, inflow velocity, and flight altitude on the flow field, aerodynamic performance, and condensation characteristics of the Royal Aircraft Establishment 2822 (RAE2822) airfoil were systematically investigated. The results show that the increase in humidity expands the supersonic region on the suction surface (Mach number peak rising from 1.1 to 1.3), reduces the static pressure coefficient, and simultaneously decreases the lift-to-drag ratio (from 2.63 to 2.33). The main condensation region under supersonic inflow conditions is located at the trailing edge, which can be initiated even at low relative humidity. The initial sub-cooling of condensation is about 15.4–15.5 K, and the peak nucleation rate under saturated moist air conditions is about 22.2. The peak droplet radius reaches 0.035 μm, and the mass flow rate is nearly twice that of subsonic flow. The increase in flight altitude suppresses condensation intensity, and the peak nucleation rate decreases with increasing altitude (such as from 16.0 to 14.4 when RH = 60%). The starting point of condensation (Wilson point) shifts backward toward the trailing edge, and the droplet radius decreases from 0.035 to 0.006 μm. This conclusion provides key data support for the aerodynamic optimization and numerical simulation of airfoils in moist air environments.