摘要
针对旋翼桨-涡干扰(BVI)现象的复杂特征,建立了一个耦合欧拉-拉格朗日数值方法用于干扰过程中脉冲气动载荷的计算。该方法将旋翼流场计算域分为两部分:在桨叶附近区域,通过求解Navier-Stokes方程来模拟流场中旋翼桨尖涡的形成;在尾迹输运区,采用自由尾迹模型表示尾迹涡的运动及其影响。噪声的计算采用基于声学类比法的FWH方程。应用上述方法以AH-1/OLS旋翼为研究对象,分析了桨盘迎角、前进比和拉力系数3个飞行参数对BVI噪声特性的影响。计算结果表明:BVI噪声具有很强指向性,受桨盘上多处干扰的共同作用,噪声可能向直升机前下方多个方向传播;通过调整下降角度和前飞速度,增大平行干扰的垂直干扰距离,可有效地规避强BVI的出现;拉力系数变化会引起传播方向的改变,而对干扰噪声的强度影响不大。
Rotor blade-vortex interaction （BVI） is a complex aerodynamic phenomenon of the helicopter. In this paper, a coupled Eulerian-Lagrangian method is established for impulsive air-loading prediction during interaction. The flow field is di- vided into two zones. A Navier-Stokes code is used to model the tip vortex formation around the blade, while a free wake model is employed in the vortex transport area to account for the effect of the far wake. The noise prediction is based on the well-known FW-H equation for acoustic pressure. With this method, a parametric study is performed to examine the effects of the descent angle, advance ratio and thrust coefficient on the BVI noise of an AH-1/OLS rotor. BVI noise has the typical feature of impulsivity and strong directivity. It may propagate in multiple directions down and forward of the helicopter be- cause several interaction events occur on the rotor. The BVI noise can be reduced by increasing the miss-distance of parallel interactions with proper descent angle and forward speed adjustment. However, decrease or increase in thrust coefficient changes only the direction of propagation, but not its magnitude.
出处
《航空学报》
EI
CAS
CSCD
北大核心
2013年第11期2520-2528,共9页
Acta Aeronautica et Astronautica Sinica
基金
江苏高校优势学科建设工程资助项目
中央高校基本科研业务费专项基金(NS2012035)
关键词
桨-涡干扰
旋翼噪声
耦合欧拉拉格朗日方法
计算流体力学
自由尾迹
直升机
blade-vortex interaction
rotor noise
coupled Eulerian-Lagrangian method
computational fluid dynamics
free wake
helicopter
