Numerical Calculation of Aerodynamic Characteristics of Low-Speed Aircraft under Heavy Rainfall Conditions

Aiming at the aerodynamic characteristics of a low-speed aircraft in a rainstorm environment, an adapted numerical computation scheme is constructed based on the computational fluid dynamics method, taking into account the continuous-phase control equations, the raindrop motion model, the wall model, and the rainfall conditions, and focusing on the effects of two wall models (the liquid film model and the collision model) on the numerical computation results. A rainstorm environment with a liquid water content of 30 g/m3 is selected, and a vehicle with a flight speed of 30 m/s is taken as an object, and the two wall models are adopted to carry out numerical calculations and mechanism analyses under the conditions of 0°, 10°, and 20° angles of attack, respectively. The simulation results show that the lift coefficients of the vehicle calculated by the two models are reduced and the drag coefficients are increased compared to the no-rain condition; the lift coefficients obtained by the wall liquid film model decrease more than those obtained by the wall collision model, and the difference in the lift coefficients calculated by the two models increases with the increase of the angle of attack; the increment of the drag coefficients obtained by the wall liquid film model is larger than that of the corresponding results of the wall collision model compared to the no-rain condition, and the difference in the lift coefficients calculated by the wall liquid film model is larger than that of the collision model. The increment in drag coefficient for the wall liquid film model relative to the no rain condition is larger than the corres-ponding result for the wall collision model, and the difference in drag coefficient results between the two models gradual-ly decreases as the angle of attack increases.