混合翼身布局客机SAX-40水上迫降力学性能数值研究

Ditching Performance of Silent Aircraft SAX-40 in Hybrid Wing-body Configuration

为了验证未来混合翼身布局飞机的水上迫降力学性能,数值求解非定常雷诺时均Navier-Stokes(URANS)方程和Realizableκ-ε湍流模型,采用动网格方法处理飞机与水面间的相对运动、流体体积(VOF)模型追踪水面变形,模拟了SAX-40飞机刚性模型以12°初始俯仰角在平静水面上迫降的过程。结果分析表明:迫降过程中,触水时的冲击作用导致飞机下表面水线附近产生较大的正压峰值,入水后的浸没滑行作用导致机身下表面尾部弯曲部分出现大面积的负压,使得飞机发生大幅抬头;迫降过程中飞机的法向载荷峰值为2.87 G,纵向载荷峰值为1.05 G,表面冲击压力峰值为720kPa。SAX-40飞机在水上迫降过程中有跳离水面的不稳定运动趋势,进行混合翼身布局设计时应予考虑。

The planned ditching of aircraft SAX-40 on calm water is numerically simulated to investigate the ditching per- formance of the hybrid wing-body configuration. The unsteady Reynolds-averaged Navier-Stokes （URANS） equations and the Realizable K-E turbulence model are solved by a fluent solver. The relative motion between the aircraft and water is handled by the dynamic mesh method. The air-water interface is tracked by a volume of fluid （VOF） model. During the ditching process, the impact brings about the positive pressure peak on the aircraft＇s lower surface near the waterline; and the pla- ning brings forth the negative pressure on the aft curved portion of the aircraft＇s lower surface, resulting in a suck force and a strong nose-up pitch motion. As the aircraft touches the water, the normal load increases rapidly to 2.87G, and the longi- tudinal load to 1.05G. The slamming pressure reaches a peak of about 720 kPa. This airplane bounces up from the water and this defective performance should be considered during the design of a hybrid wing-body configuration.