Research On Modeling And Application Technologies Of Wind Field In Virtual Test

In the design and development processes of aircraft, such as airplane and missile, using virtual test instead or partly instead of real flight test, can not only reduce costs and shorten the development cycle, but also be safer. Compared with real test, virtual test can accomplish the flight test under a variety of extreme environmental conditions, and the test result is more sufficient and comprehensive. Dring the flight, aircraft is always influenced by the wind. In order to make the result of virtual test approach to it of real test, wind model nust be built to simulate the real wind field. In addition, some virtual test's intention is testing the aircraft's response to atmospheric disturbances, in which it is more important to create a flexible and diverse virtual wind field.Virtual wind field simulation software supports testing personnel to use various basic wind field models to constructe the complex wind field. Different from the wind field models in the simple flight simulation, wind field models in virtual test need to surpport the diversified virtual tests for virtual, real and part-real aircraft prototypes. Thereby, wind field model in virtual test is required to operate in real time. Simultaneity, in order to satisfy the diversified virtual tests, virtual wind field is required to have the capability of flexibly configuring the inside wind field models'parameters and using the simplly basic wind field models. Aiming at the above problems, the works presented in this dissertation focus on the wind field modeling technologies. The contents are detailed as follows.1. Research on atmospheric turbulence model for virtual testAiming at the poor real-time performance existing in present three-dimensional atmospheric turbulence field, a new three-dimensional atmospheric turbulence field is modeled based on correlation function method. This method generates the whole three-dimensional atmospheric turbulence data by using a recursion matrix. It only needs a small quantity of computation and fewer computer memory. And this generation method can meet the real-time requirment.Considering that some complex aircraft prototypes need particularly calculate the atmospheric turbulence values in different locations of the aircraft, a method of atmospheric turbulence field simulation is proposed. This method establishes the stochastic process model of atmospheric turbulence detailed simulation based on decomposing the correlation matrix, and counts the model parameters by the correlation matrix of atmospheric turbulence value on different locations of the aircraft, and then calculates the atmospheric turbulence values on different positions. This method can meet the correlation of atmospheric turbulence values between different locations on the aircraft, and simultaneously guarantee the correlation along the flight track. It has highly fidelity in the virtual test.2. Research on microburst model for virtual testThe characteristic of velocity filed induced by vortex ring can meet most microburst velocity filed. So the microburst filed is usually modeled using vortex ring principle in the project. However, there are odd points in the vortex filament which will impact on the simulation facticity. The range of velocity filed which is weakened by traditional solutions is so big that the distribution of velocity is affected. Accordingly, a new damping factor is advanced by theoretical analysis according to the vortex core boundary conditions, which can weaken wind speed inside the vortex core and has no effect outside the vortex core. This method can better solve the strange problem in the vortex filament.Compared with single vortex ring model, the velocity field of multiple vortex ring model is more close to actual microburst field, and is widely used. At present, the parameter selection is so discretionary that the characteristic of the generated microburst usually presents a big contrast to the expectation. Aiming at above problems, a new parameter selection method based on Nested Particle Swarm Optimization (NPSO) is proposed, which can select the parameters according to the intensity and the proportion between maximal horizontal velocity and maximal vertical velocity of the microburst. This method can make the generated microburst meet the expecting virtual test better.3. Establishment and application of wind filed software model for virtual testThe virtual test wind field software model is established based on Object Oriented method. The structure frame of virtual test wind field is designed, which supports to establish complex wind field by stacking and composing all kinds of the existing basic wind field models. The opened database of basic wind field models and the general external interface ensure the model's good expansibility and reusability. The static and dynamic models of the virtual test wind field is established, which describe the internal logic and external interaction relationship. It is convenient for the future development, maintenance and expansion of the virtual test wind field.The virtual test wind field simulation nodes are established according to the HIT-GPTA architecture standard based on the virtual test wind field software model. The established atmospheric turbulence model, microburst model and present mean wind model are added into the basic wind field database after encapsulating in term of standard interface. Using these basic wind field models to establish the complex wind, and appling it in some missile virtual test indicate that the virtual test wind field software model is correct and every basic wind field model can be used in real-time.