任晓峰, 段卓毅, 魏剑龙. 滑流对飞机纵向静稳定性影响的数值模拟[J]. 空气动力学学报, 2017, 35(3): 383-391. DOI: 10.7638/kqdlxxb-2017.0006
引用本文: 任晓峰, 段卓毅, 魏剑龙. 滑流对飞机纵向静稳定性影响的数值模拟[J]. 空气动力学学报, 2017, 35(3): 383-391. DOI: 10.7638/kqdlxxb-2017.0006
REN Xiaofeng, DUAN Zhuoyi, WEI Jianlong. Numerical simulation of propeller slipstream effects on pitching static stability[J]. ACTA AERODYNAMICA SINICA, 2017, 35(3): 383-391. DOI: 10.7638/kqdlxxb-2017.0006
Citation: REN Xiaofeng, DUAN Zhuoyi, WEI Jianlong. Numerical simulation of propeller slipstream effects on pitching static stability[J]. ACTA AERODYNAMICA SINICA, 2017, 35(3): 383-391. DOI: 10.7638/kqdlxxb-2017.0006

滑流对飞机纵向静稳定性影响的数值模拟

Numerical simulation of propeller slipstream effects on pitching static stability

  • 摘要: 针对某“机身+机翼+襟翼+短舱+螺旋桨+平尾”简化构型,开展低速大拉力系数工况下强螺旋桨滑流的数值模拟。模型为翼吊双发布局,动力计算时分为三个计算域,分别为两个包含螺旋桨的旋转域和一个静止域。采用商业软件ICEM CFD生成多块面搭接非结构网格,在机体表面和滑流区域对网格进行加密以便于捕捉螺旋桨滑流的发展及其与机翼、尾翼等部件之间的干扰。采用ANSYS CFX软件求解雷诺平均Navier-Stokes方程,使用多参考坐标系(MFR)方法模拟螺旋桨的旋转。基本构型有/无动力的计算结果表明螺旋桨动力及其产生的滑流对模型的纵向静稳定性影响较大,模型的纵向静稳定性在迎角较小时下降明显甚至丧失,在迎角较大时反而略有增加。一般而言,涡桨飞机平尾处的流场受气动布局、迎角、机翼及襟翼的下洗和螺旋桨滑流及其强度等因素的共同影响。对模型各部件的俯仰力矩特性及尾翼区流场细节进行详细分析可知,小迎角时飞机纵向静稳定性的下降是由于平尾受到机翼及襟翼较强的下洗作用而导致效率下降,而此时平尾没能进入滑流区,不能有效利用滑流区内高能气流来提高平尾效率。并且由于两个螺旋桨同为逆时针旋转,右侧平尾的贡献高于左侧平尾。为了验证这一结论,分别将螺旋桨向上平移0.7m和将平尾下移0.86m并进行数值模拟,结果表明平尾对模型纵向静稳定性的贡献均有增加。

     

    Abstract: A simple "body+wing+flap+nacelle+propeller+horizontal tail" model(Model A) and two modified ones(Model B and C) were simulated via commercial CFD codes, using unstructured surface matching grid and multi-frame of reference technique to solve Reynolds Averaged Navier-Stokes(RANS) equations. For the simulations, the whole computational domain was divided into three individual domains, namely two rotating domains for the propellers and one stationary domain. The slipstream effects at low speed and in high thrust coefficient condition were studied. It has been demonstrated that the pitching static stability of'Model A'decreases sharply at low angles of attack, while increases slightly at high angles of attack due to the thrust generated by the propellers, the downwash effect of the wing and flap, and the interaction between the slipstream and horizontal tail(H-tail). Generally, the flow field around H-tail of a propeller-driven aircraft is affected by the general layout, the angle of attack, the downwash of the wing and flap, and the slipstream effect. More specifically, the downwash rate of the wing and flap increases due to the slipstream effect, while the efficiency of the H-tail decreases throughout the whole computed range of angles of attack. Since H-tail is not immersed in the slipstream, the high-energy fluid can hardly be utilized to increase its efficiency at low angles of attack. Moreover, it can be seen that the left H-tail contributes to the stability of'Model A'due to the counter-clockwise rotation of the two propellers.In order to improve the efficiency of H-tail, designers are suggested to modify the relative position between H-tail and the propeller slipstream to make sure that H-tail can be surrounded by high-energy flow generated by the propeller. Moving up the propeller by 0.7m(Model B) or moving down the H-tail by 0.86m(Model C) has been proved as feasible modifications to increase the pitching static margin at low angles of attack.

     

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