Surface Roughness Measurements on Gas Turbine Blades

Results are presented from profilometer measurements of the surface roughness on in-service turbine engine blades from F-100 and TF-39 aeroengines. On each blade, one roughness profile is taken in the region of the leading edge, the midchord and the trailing edge on both the pressure and suction sides for a total of six profiles. Thirty first-stage turbine blades are measured from each engine. Statistical computations are performed on these profiles and the root mean square height, skewness and kurtosis of the roughness height distribution are presented along with the correlation length of the autocorrelation function. The purpose of this work is to provide insight into the nature of surface roughness characteristics of in-service turbine blades which can be used in the development of scaled laboratory experiments of boundary layer flow and heat transfer on turbine engine blades.