A Selective Review of Transition Modelling for CFD.

This paper aims to give an overview of the more widely used approaches to model transition in Computational Fluid Dynamics (CFD). Eight different methods are reviewed: the stability theory approach, the low Reynolds number turbulent closure approach, the intermittency transport method with integral correlations, the intermittency and the vorticity Reynolds number approach, the laminar fluctuation energy method, the ν/-2- f model, and the Large Eddy Simulations (LES) and Direct Numerical Simulations (DNS) for transition. The approaches are compared to one another, highlighting their respective advantages and drawbacks. From this analysis, a list of desirable features for CFD transition models is drawn up, against which the eight approaches are scored

Effects of Laminar-Turbulent Transition on the Shock-Wave/Boundary-Layer Interaction

This paper presents results of experimental investigations of the nominally 2-D impinging shock-wave interaction with the transitional boundary layer developing on a flat plate at Mach 6 flow conditions. Experiments were conducted in the Ludwieg-Tube Facility at DLR Göttingen using quantitative infrared-thermography, high-speed shadowgraphy and free-stream Pitot-pressure fluctuation measurements. Natural-transition and shockimpingement locations on the flat plate were varied independently in order to establish different initial boundary-layer conditions at the interaction region. The results demonstrate significant impact of these mutual positions on the induced flow topology and on the heat-flux distribution. A range of CFD-validation test cases was created representing transition phenomena in some details. The distribution of the normalized Stanton number, generalized in the present work for a wide range of unit Reynolds numbers, indicate a clear narrow maximum inside the transition region

Transition Detection and Skin Friction Measurements on Rotating Propeller Blades

The laminar-to-turbulent transition on high-speed rotating propeller blades is investigated in the present work experimentally. The analysis of limitations for optical skin-friction measurements by the oil-film interferometry, as well as of the results of feasibility experiments in the low-speed wind-tunnel BLSWT of AIRBUS Bremen at propeller rotation rates from 3000 up to 14400 rpm (50-240 Hz) and free-stream flow speeds between 30 and 70 m/s are included. The effects of Reynolds number and of the propeller advance ratio on the transition location and flow topology are discussed

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