Experimental study of the turbulent flow in a plane asymmetric diffuser

Sammanfattning: The separating turbulent flow in a plane asymmetric diffuseris investigated experimentally. The considered flow case issuitable for fundamental studies of separation, separationcontrol and turbulence modelling. The flow case has beenstudied in a specially designed wind-tunnel under wellcontrolled conditions. The velocity field has been mapped outwith PIV and LDV techniques in order to determine all threevelocity components. Knowledge of all velocity componentsallows the formation of several quantities of interest inturbulence modelling such as the turbulencekinetic energy, theturbulence anisotropy tensor and the turbulence production ratetensor. Pressures are measured through the diffuser. Themeasured data will form a reference database, which can be usedfor evaluation of turbulence models and other computationalinvestigations. A comparative study is made where the measuredturbulence data are used to evaluate an explicit algebraicReynolds stress turbulence model (EARSM). A discussionregarding the underlying reasons for the discrepancies foundbetween the experimental and the model results is made. Asimple form of separation control using vortex generators istested with positive result.Descriptors:Fluid mechanics, wind-tunnel, turbulence,turbulence modelling, EARSM, asymmetric diffuser, boundarylayer, PIV, LDV, vortex generator, control.