共轴高速直升机振动载荷计算分析模型

共轴高速直升机上下旋翼之间存在强烈的气动干扰现象,这对旋翼的气动特性影响较大。本文根据这一特点并考虑气弹耦合计算效率,利用单旋翼自由尾迹模型的尾迹几何和固定尾迹计算的初始诱导速度分布作为共轴双旋翼预定尾迹模型的初始迭代值。与Leishman-Beddoes非定常动态失速模型、Pitt-Peters动态入流模型、共轴直升机上下旋翼桨叶全本征动力学方程及弹性桨叶与变距轴承边界约束条件等计算模块相结合,建立了一种考虑上下旋翼之间气动干扰及耦合迭代的共轴双旋翼振动载荷计算模型。为验证本分析模型的计算精度,以西科斯基公司的验证机XH-59A为研究对象,与国外风洞试验结果进行了对比,两者吻合较好。

Mathematical Analysis Model for Vibration Loads of a Coaxial High Speed Helicopter

The strong aerodynamic interference exists between the upper and lower rotors of a coaxial high speed helicopter, which has a significantly influence on the aerodynamic characteristics of the rotors. Based on the feature and considering the efficiency of the aeroelastic coupling calculation, the initial induced velocity distribution calculated by rigid-wake model, together with the wake geometry feature of a single rotor calculated by free-wake model, are the initial iteration values for the prescribed-wake model of a coaxial helicopter. The main calculation modules:The blade fully intrinsic dynamic equations of the coaxial twin rotors, the constraint equations between the blade and the bearings and the aerodynamic models, including the wake models and Leishman-Beddoes unsteady dynamic stall model and Pitt-Peters dynamic inflow model, are the basis for establishing a computational model of the coaxial twin rotors vibration load considering the aerodynamic interference and coupling iteration between the upper and lower rotor. The forces and moments on the sample XH-59A, which is the certification machine of Sikorsky, are calculated with the help of the model. The computational results are in good coincidence with those from the wind tunnel test.