Research On Real-Time Flight Simulation Of Large Aircraft In Complex Atmospheric Disturbance

Aircrafts would encounter many kinds of atmospheric disturbance during flight,such as low-altitude wind shear, atmospheric turbulence, et al. The aircraft would subject to buffeting by random turbulence. Turbulence would affect passengers'ride comfort. What's more, it would produce fatigue in aircraft structure chronically. As a kind of hazardous weather, various low-altitude wind shear would do harm to takeoff and landing. Once the pilot made wrong instructions or did not escape wind field in time, a serious flight accident would be suffered. It is meaningful to simulate flight in complex atmospheric disturbance in flight simulator, which can be used for research and pilot education. In this dissertation, several atmopheric disturbance models and large aircraft flight simulation models have been built. Based on these models, the large aircraft flight through atmospheric disturbance has been studied.Firstly, three-dimensional (3-D) mathematical model of low-altitude microburst wind shear, medium or high-altitude atmospheric turbulence were built. A parameterized model of 3-D microburst model was built based on vortex ring and Rankine vortex principle in fluid dynamics. Multiple complicated microburst wind field can be simulated in high fidelity by ring declination and superposition. Compared to real wind field, the built model can be not only used in real-time flight simulation, but also in real wind field simulation. It can be applicated to flight accident recurrence, et al.The generating and extending method of 3-D atmospheric turbulence field were put forward. The spatial turbulence field based on von Karman model is generated in frequency domain by using Monte Carlo method, and then transformed back to time domain with 3-D inverse Fourier transform. In this way, the complex factorization in time domain can be avoided. The turbulence strength and integeral scale can be varied according to flight altitude by dimensionalization during simulation. Taking account of the aircraft flying through the turbulence incessantly, a symmetrical extension method of the field is designed in order to simulate with high fidelity.Secondly, based on Boeing747-100B aircraft modeling data, the QZSim flight dynamics model has been built by embedded database and real-time simulation platform. It can run on PC and can be used in flight simulator. According to the characterics of the modeling data, the pre-made method and real-time flight simulation database organization based on Bekerley DB were studied. Combined with modeling and validation requirement of real-time flight simulation system in flight simulator, this dissertation built the core dynamics model, aerodynamics model, engine model, control system model and atmopheric environment model, et al. All the sub-system models were validated respectively. QZSim model has been built on Windows+RTX. By real run on light flight simulator, the QZSim dynamics model shows good performance and simulation fidelity.After building the whole model, this disseration did research on the validation of the dynamics model. An improved Newton-Raphson trim algorithm was designed to trim the six degrees of freedom (6-DOF) flight state by selecting restriction condition and search scope properly. The longitidinal and lateral dynamics modes were tested which are compared with real flight test data. The results show that the phugoid mode, short-period mode and Dutch roll mode accord with flight test data perfectly. The dynamics response to control were compared and analyzed with linear transfer function model.Lastly, the dynamic response of large aircraft flight through low-altitude microburst, atompheric turbulence, was studied by numerical simulation based on atmospheric disturbance model and B747 flight dynamics model. Compared with small aircraft, mass-point assumption cannot be applied to large aircraft as the fuselage scale can be comparable with medium or small scale wind field. Based on dynamics model in static atmophere, a general modification method of dynamics model in atmospheric disturbance was put forward. Based on the research, the real-time longitudinal and lateral escape simulation of large aircraft flight through low-altitude microburst was studied. Based on mass-point model and four-point model, this dissertation did research on aircraft flight through atmospheric turbulence. Several meaningful conclusions are acquired. What's more, the research shows that the flight simulation model can support real-time simulation of aircraft flight through complex atmospheric disturbance.