Unsteady Heat Flux Measurements of Junction Flow With Reynolds Number and Freestream Turbulence Effects

摘要

Turbulent junction flow is a three-dimensional unsteady phenomenon occurring in the flow upstream of the leading edge of bodies attached to a surface, such as in turbine rotors and stators, heat exchangers, submarine appendages, and wing-fuselage attachments. One of the signature features of this type of flow is the presence of bimodal behavior in the probability density functions of velocity, but the bimodal phenomenon has not been observed in surface heat flux measurements. However, it is well-known that time-mean levels of heat flux are significant. In situations where the body experiences high freestream turbulence, mean heat flux is further increased, but the mechanisms of the enhancement are unclear. In this paper, a test section for simultaneous time-resolved heat flux and flowfield measurements in front of a common research wing is highlighted. Time-resolved unsteady heat flux is also reported for a range of Reynolds numbers at high freestream turbulence. Time-resolved heat flux measurements from the symmetry plane of the junction region are compared with measurements downstream of the airfoil to determine if there are correlated behaviors. Also, a comparison between the effects of baseline freestream turbulence and high freestream turbulence on junction heat transfer is presented. It is found that at the plane of symmetry, high freestream turbulence increases endwall heat transfer at low Reynolds number and has negligible influence on endwall heat transfer at high Reynolds number.