Virtual Reality Technique Based3D View Of The Surface Pressure Under Wind Tunnel Model

Virtual reality technology is a cutting-edge technology which benefits from thedevelopment of multimedia technology. It can generate three-dimensional lifelikevirtual environment by employing three-dimensional graphic producing technology,multi-sensor interaction technology, and high-resolution display technology. Virtualreality technology is highly practicable, which is developed to satisfy the requirement ofmilitary and aerospace field at the beginning. Recently, it has been widely applied toindustries and design of architectures. Virtual reality technology is changing our life.A wind tunnel is a research tool used in aerodynamic research to study the effects ofair moving past solid objects. Wind tunnel models, as the objects of research (e.g.,aircrafts, motor vehicles, skyscrapers and ships and so on), are installed in the windtunnel in order to study the flow of gas around models and the interaction betweenmodels and gas, thus, aerodynamic characteristics of corresponding real objects can beknown. Surface pressure, obtained from the pressure experiment (an important item ofwind tunnel experiments), can illustrate the distribution of aerodynamic characteristics.On the surface of models used in the pressure experiments, there are rows of pressureports connected with scanning electronic valves inside the models, and the pressure datacan be acquired from the computer terminal of scanning electronic valves. The maintasks are listed as follow:(1)Based on the contrast analysis of DirectX and OpenGL, an applicationprogramming interface is selected to implement three-dimensional display of pressureon the surface of models.(2)Study the current three-dimensional graphics engine design, module division andprocess design. Combined with the mathematical module design, the general design ofthree-dimensional graphics engine in specific application is presented.(3)Combined with3D geometric transformation and data structures, based on thediscussion of four different types of light sources and two shaded mode in graphicsrendering engine, the texture mapping, z-cache and rasterization3D pipeline build stepsare discussed, a simple graphic rendering engine is presented.(4)Taking the concrete wind tunnel models into account,3DS data format used byfiles of wind tunnel models and its access method are introduced. After setting thepressure ports and color range of surface of wind tunnel models and constructing the virtual scene, three-dimensional display of pressure on the surface of models isimplemented by rendering the virtual scene.In this article, based on virtual reality technology, the three-dimensional display ofpressure distribution is discussed. And it can offer the related test engineers an approachto obtain the data wind tunnel experiments and directly observe the pressure change onthe surface of the entire model which facilitate the research of the distribution ofaerodynamic characteristics and improve the design efficiency of real objectsappearance.