Research on Aerodynamic Shape Design Scheme of a Distributed Propeller Transport Aircraft and Its Slipstream Effect

一种分布式螺旋桨运输机方案及其滑流效应研究

Computational Aerodynamics Institute, China Aerodynamics Research and Development Center, Mianyang 621000, China

Received: 18 May 2018

Abstract

With the continuous development and widespread attention of electric propulsion technology in traditional transportation fields such as automobiles and trains, the distributed propeller propulsion technology applied to electric or hybrid electric medium and small scale aircrafts has become a new topic in aviation research. This paper presents a preliminary design scheme of a distributed propeller electric propulsion transport aircraft firstly. Then, based on Reynolds average N-S equations, combined with the SA turbulence model, and replaced the real distributed propellers with simplified disk model, the aerodynamic characteristics of the aircraft with and without slipstream under the condition of low speed and high thrust at low altitude are analyzed. Finally, the effects of pressure distribution, pitching moment characteristics and wing flow on distributed propellers are studied in detailed. The results show that the lift and drag of the aircraft with slipstream are both larger than without slipstream and with slipstream effect, the pitching moment of the wing decreases, the pitching moment of the tail increases. When the tail is far away or completely inside the region of slipstream, the difference of pitching moment of the tail with and without slipstream is little, and the difference is obvious as the tail is only partially in the region of slipstream; When the diameter of distributed propellers is far larger than the wing thickness, more propeller power is used to shove air flow away from the surface area of the wing, and resulting in an insignificant increase in the coefficient of lift.

摘要

随着电推进技术在汽车、火车等传统运输领域获得不断发展和广泛关注，应用于纯电动或油电混合动力中小型飞行器的分布式螺旋桨推进技术已成为航空研究新热点。首先提出了一种分布式螺旋桨电推进运输机初步方案；然后，基于雷诺平均N-S方程，结合SA湍流模型，运用等效盘代替真实分布式螺旋桨，完成该机低空低速大拉力状态下的有无滑流全机气动特性分析；最后，重点对机翼和尾翼的压力分布、俯仰力矩特性以及分布式螺旋桨下机翼流动进行滑流影响研究。分析结果表明：有滑流状态下升阻力均较无滑流大，且有滑流较无滑流状态机翼低头力矩大，尾翼抬头力矩较大；尾翼离滑流区较远或完全处于滑流区时，有无滑流状态下尾翼俯仰力矩差量较小，而尾翼仅部分处于滑流区时，差量较大；分布式螺旋桨直径相对机翼厚度较大时，更多的螺旋桨功率用于对远离机翼表面区域的气流做功，引起升力系数增加不显著。