适于直升机飞行仿真的高原大气紊流模型

Highland atmospheric turbulence model for helicopter flight simulation

发展了一种适于直升机飞行仿真的高原大气紊流模型。首先,考虑地形地貌、大气层结、平均风速廓线的影响,给出高原大气紊流的功率谱密度模型及其统计特性参数,采用最小二乘法建立有理形式的高阶紊流成型滤波器,并采用零极点匹配法将其离散形成时域紊流速度生成算法。在此基础上,采用协方差矩阵Cholesky因子分解的线性变换法建立空间相关的大气紊流成型滤波器,采用“冻结场”假设沿飞行速度方向扩展,形成覆盖直升机各气动面的三维空间大气紊流模型。最后,将上述紊流模型集成到已有直升机飞行动力学模型并进行非线性仿真验证。结果表明,该模型能够准确捕捉高原地形地貌、大气层结、风速廓线等因素对大气紊流速度的影响;集成大气紊流的飞行动力学模型能够准确捕捉大气紊流对直升机运动的动态干扰特性。

This paper presents a highland atmospheric turbulence model for helicopter flight simulation. First, a spectrum model and statistical parameters of atmospheric turbulence velocity are provided considering the influence of highland topography, atmospheric stability, and mean wind speed profile. High-order shaping filters are developed by the least-square curve fitting method, and the zero-pole matching method is used to discretize the filters to form recursive algorithms for time-domain turbulence components. On this basis, spatially correlated atmospheric turbulence shaping filters are established by linear transformation with the Cholesky factorization of the covariance matrix. The “frozen field” hypothesis is used to expand the turbulence components along the direction of airspeed to form a three-dimensional atmospheric turbulence field covering all helicopter aerodynamic surfaces. Finally, the turbulence model is integrated into a helicopter flight dynamics model for flight simulation and validation against flight test data. The results show that the proposed turbulence model can accurately capture the influence of highland topography, atmospheric stability, and wind speed profile on the statistical characteristics of the atmospheric turbulence components. The integrated turbulence and flight dynamics model can accurately model the helicopter frequency response to atmospheric turbulence.