Fluid Flow Pattern Visualisation: An Alternative Approach Using Highly Resolved Heat Transfer Experiments

The present study demonstrates an alternative approach for describing fluid flow characteristics very close to the wall, using locally resolved heat transfer experiments. Convection coefficients on the base surface and around a surface mounted vortex generator of delta-wing shape design, are evaluated with the transient liquid crystal technique over a range of freestream velocities. Therefore, the spatial variation of exponent m in the equation Nu~Rem, which is directly linked to the structure of the boundary layer, can be determined over the complete heat transfer area. The surface distributions of exponent m are directly compared to the footprint of the flow obtained with oil and dye flow visualization indicating a more appropriate interpretation of the near wall flow structures compared to the heat transfer coefficients.