Generation and Application of Spatial Atmospheric Turbulence Field in Flight Simulation

This article deals with generation and application of three-dimensional (3D) atmospheric turbulence field in large aircraft real-time flight simulation. The modeling requirements for the turbulence field of large aircraft flight simulation are analyzed here. The spatial turbulence field is generated in the frequency domain by using the Monte Carlo method, and then transformed back to the time domain with the 3D inverse Fourier transform. The von Karman model is adopted for an accurate description of the turbulence field. The conjugate symmetry characteristics of the Fourier transform is used to ensure the real turbulent wind in the time domain. Given that the integral scale and intensity of turbulence varies with flight altitude, a nondimensional turbulence field is generated. An algorithm for calculating the turbulent wind gradients is presented. Taking account of the aircraft flying through the turbulence incessantly, a symmetrical extension method of the field is put forward. The correlation test shows that the generated turbulence field achieves a better performance in a cross-correlation test as compared to the traditional method, in the time domain. A simulation of a Boeing 747 aircraft flying in the turbulence field is conducted. Compared to the mass-point model, the algorithm based on spatial turbulence and a four-point model shows better stochastic characteristics during the flight through the field.