Flow and thermal structures in a transitional boundary layer

Abstract

A three-wire probe was specifically designed and fabricated to measure the flow structure and the thermal field in transitional and low Reynolds number turbulent flow. In addition to the skin friction coefficient and Stanton number on the surface, detailed measurements were made of the mean and fluctuation quantities of the flow and temperature fields in the boundary layer. The evolution of the uv profiles indicates that turbulent shear is generated near Y + = 70–100 and imposes itself on the wall within the boundary layer, ut, vt, ϵ H , ϵ M , and Pr t were measured near the end of transition and in the turbulent flow region. Pr t is shown to be greater than the typical value of 0.9 in the near-wall region. The Reynolds analogy factor (2 St/ C f) in the early turbulent flow region is approximately 0.9, which is lower than the typical value of 1.2 for turbulent flow. The data presented in this paper serve as the baseline for a series of consecutive studies related to investigating various parameters that affect laminar-turbulent transition.