大型水陆两栖飞机侧风起降的滑流影响分析

大型水陆两栖飞机AG600的动力装置为安装在机翼上的4台同向旋转涡轮螺旋桨发动机，针对1：15缩比模型带动力风洞试验显示的螺旋桨滑流对侧风起降状态的偏航力矩不稳定影响，对全机带动力风洞试验模型进行了大规模并行非定常数值计算，再现了风洞试验现象，通过流动机理分析明确其产生原因主要是左侧滑时右外翼分离和垂尾背鳍涡破裂，这些原因和数值模拟的准确性也为后期的风洞试验所证实。考虑到模型风洞试验中尺度限制造成的低雷诺数和高螺旋桨转速，为保证飞行安全，继续采用该非定常方法对全尺寸飞机真实侧风起降状态进行了详细数值分析和偏航稳定性评估。研究结果显示，在飞行雷诺数和螺旋桨转速下，相同侧风范围内风洞试验显示的流动不稳定因素基本消失，偏航稳定性允许的侧风范围明显增加。本研究实现了四发螺旋桨飞机起降状态横向气动特性的滑流影响非定常数值分析，建立了基于计算流体力学的风洞与飞行雷诺数效应的相互关系，进行了偏航稳定性的虚拟试飞评估，研究成果也为AG600飞机的首飞和飞行试验所验证。

Propeller slipstream interference of large amphibian aircraft under take-off and landing configuration with crosswind

The propulsion system of the large amphibian aircraft AG600 includes four turboprop engines rotating in the same direction. Targeting the unstable interference of propeller slipstream to the yawing moment appeared in the wind tunnel test of a 1:15 model take-off and landing configuration under crosswind, a large scale parallel unsteady numerical simulation is conducted for the powered wind tunnel model. The numerical simulation re-produced the wind tunnel observations, showing that the outboard wing separation and the dorsal-fin vortex breach are the major causes, which are verified by a later wind tunnel test. Considering the lower Reynolds number and the higher propeller rotating speed due to the limited size of the wind tunnel model, an unsteady numerical analysis and an yawing stability estimation are continued for the full size aircraft under real flight take-off and landing condition with crosswind, ensuring flight safety. The results of the computation show that, under flight Reynolds number and propeller rotating speed, the flow separations at wind tunnel condition disappear under the same yawing angle, and the acceptable crosswind range for yawing stability has significantly increased. The present investigation realizes the unsteady analysis of the slipstream interference on the lateral aerodynamic characteristics of four propeller aircraft take-off and landing configurations, establishing the Reynolds number correlation of wind tunnel test and full size flight via computational fluid dynamics. The study also assesses the virtual flight test. The research results are verified by the first flight and the following flight test of AG600.