Numerical simulation of flow conditioning device design in wide angle diffuser of continuous transonic wind tunnels

Large area expansion can be achieved effectively by wide angle diffusers in wind tunnels, while the airflow separation may occur at the same time. In order to ensure the flow field quality, the separation must be suppressed. Utilizing damp-screens with reasonable parameters is a valid method in engineering. With the background of 0.6m continuum transonic wind tunnel, so as to test the engineering design method of damp-screens, we verify the preliminary result by the method through the way of numerical simulation. From the calculation, by taking the scheme 3-4, loss coefficients for two screens are 1.6 and 1.0 respectively, the RMS value at the outlet of the wide angle diffuser will be 14.5%; considering the influence by the environment and adjusting the two coefficients to 0.8 and 1.0, the RMS value will be 16.2%. The research indicates that, the engineering design method, in addition to numerical simulations, can be effectively applied in the design of wide angle diffusers. Suppressing the airflow separation, reducing the pressure loss, and improving the exit velocity uniformity can be achieved simultaneously.