Combined Effects of Freestream Turbulence, Pressure Gradients, and Surface Roughness on Turbine Aerodynamics

摘要

This work used scaled facsimiles of real turbine blade surfaces to characterize correlations between turbine blade roughness, freestream turbulence, pressure gradients and skin friction (Cf). Addition of roughness caused Cf to increase: up to 300% for the roughest surface. Addition of freestream turbulence resulted in 125% increase for the same surface. The combined effects showed increases up to 380%. Although decreasing roughness, freestream turbulence, and Reynolds number resulted in less dramatic results, it was concluded that the Cf increases due to combined effects were consistently higher than their corresponding sum of the parts. The combined effects of roughness and pressure gradients yielded inconclusive results, however, limited observations seem to corroborate the trends seen during zero pressure gradient tests.