GAS FLOW CONTROL IN A WIND TUNNEL

Abstract

Power unit (compressor, fan, etc.) wind tunnel (ADT) to create airflow in which to put the object model for experimental research. We need an algorithm for support (flow control) of the velocity head, and the speed with precision and change the function of the transition from current values to set.Mathematical model of gas movement takes into account the state of the thread, geometry and surface quality elements ADT, as well as the dynamics of power installation. Turbulent motion of a viscous incompressible gas is described by the Stokes equation and the continuity. The uniqueness of a solution accomplished by setting boundary and initial conditions.Differential pressure generated by the power plant, is spent to overcome the hydraulic resistance caused by the forces of the resistance and friction. Value of pressure drop for a given velocity, and flow rate is determined from the solution of the problem of stationary motion of the gas. Use of methods and algorithms of determination of coefficients of friction resistance and local forces. Resistance of the object model, power plants, etc. are measured and determined in real-time experiment.The solution of nonstationary equations of axisymmetric motion of gas in a cylindrical coordinate system with boundary and initial condition is obtained by the method of separation of variables as a combination of involuntary movements from changes in the pressure gradient in the absence of initial motion and change movement caused the initial state.The value of velocity and volumetric flow rate is determined in the form of series of special cylindrical functions in the assumption of possible expansion of describing the dynamics of the energy facility, in Fourier series on the observation interval.Shows the structural and functional scheme of the system of flow control, which performs the rough (output into the specified area) and exact (support of parameter values) the regulation and management of the experiment. The algorithm flow control and the stationary solution of the problem is presented in the form of procedures. Application software includes two levels, interacting through shared memory. To implement the algorithm proposed in the operating system of real time QNX/ Linux on the first and W CE on the second level of the system. In the future will be tested tools and methods to support the experiment in real time.