ロケットフェアリング周りにおける遷音速湿り空気流れの数値流体解析

抄録

We aim to investigate radius of water drop (rocket clouds) and mass fraction of the liquid phase in transonic wet air flow around a rocket fairing, and the aerodynamic characteristics of the fairing. In this study, a two-dimensional or axisymmetrical two-dimensional CFD code considering the heterogenous condensation (wet air flow) is developed. The numerical simulation is validated by a solving flow in channel with circular-arc bump. The dry and the wet air flow around the rocket fairing (simulated 4S-type for H-IIA, Length of 12 m, M_inf = 0.85, T_inf = 300 K, P_inf = 1000 hPa) are solved by the numerical simulation. In the case of the wet air flow around the rocket fairing, the Mach number and the mass fraction of the liquid phase are 1.45 and 1.08% respectively near the shoulder of the fairing z = 66.1 m (the fairing tip is located at z = 60 m). The maximum radius of a water drop is 0.27 μm. Water drops, which their radius is over 0.11 μm, are generated near the shoulder of the fairing. The water drops are likely of being observed as the rocket clouds like umbrella. Compared to the case of the dry air flow, the shock position on the rocket fairing wall is shifted to downstream in the case of the wet air flow due to the condensing heat in the wet flow. The difference of the static pressure between the dry and wet air flow is observed on the side wall of the fairing from z = 66.1 m to 68.5 m. In particular, the static pressure of the wet air flow is 7.20 kPa higher than that of the dry air flow near the shoulder of the fairing.