Influence of Curvature-Driven Favorable Pressure Gradient on Supersonic Turbulent Boundary Layer
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The influence of a wall curvature-driven favorable pressure gradient on the turbulent and mean flow properties of a Mach 2.9 boundary layer (Rex = 1.23 107) were investigated using laser Doppler velocimetry. A zero-pressure-gradient boundary layer (Rex = 1.35 107) was also mapped for comparative purposes. In addition to the typical mean and turbulent statistical properties, the data in this study were acquired with the specific goal of resolving the mean strain rates in all three coordinate directions; these data allowed for measurement of extra Reynolds shear-stress production terms. The maximum magnitude of the distortion was 0.1, which indicated that the pressure gradient was strong. The expected stabilizing effect on the turbulence intensities was observed. Near the wall, the kinematic Reynolds shear stresses were reduced by approximately 75%. Above y/ 0.4 the favorable pressure gradient induced a negative Reynolds shear stress, whereas the main strain rate remained positive. The reduced shear-stress levels were attributed to negative overall production and the use of a body-intrinsic coordinate system for data collection.
