总距突增时共轴式直升机瞬态操纵响应分析

从共轴双旋翼直升机的工程实际出发,建立了共轴式直升机上下旋翼非定常气动特性的计算模型.引入Leishman-Beddoes指数函数的半经验公式,建立了二维翼型非定常气动模型;分别从固定尾迹和自由尾迹,引入干扰因子到动态入流三种方法出发,建立了反映共轴双旋翼直升机上下旋翼气动干扰的诱导速度模型;从跷跷板式旋翼的挥舞动力学方程出发,利用4阶Runge-Kutta算法求解桨叶刚性挥舞角的数值解.通过计算分析,得到了悬停和前飞状态,总距突增时上下旋翼升力的动态响应特性,以及总距突增时上下旋翼桨叶铰链力矩的响应特性.

Dynamic response analysis of a small-scale coaxial helicopter to a rapid collective pitch increase

Based on the engineering reality,a calculation model of the rotor unsteady aerodynamics of the small-scale coaxial helicopter had been set up.An airfoil unsteady aerodynamic model was established by introducing a set of Leishman-Beddoes semi-empirical indicial response formula.The induced velocity of the aerodynamic interaction between upper and lower rotors of a coaxial helicopter was set up based on the rigid wake model,free wake model and the dynamic inflow model with interference factors.Considering the teetering rotor’s particular flapping dynamic formula,the Runge-Kutta method was used to obtain the numerical solution of the rigid blade flapping angle.According to the calculation and analysis,the thrust response to a rapid collective pitch increase in both the hovering and forward flight states were obtained,and the blade’s hinge moment of the upper and lower rotors were compared.