| In-service damage to compressor or turbine blades is a common cause of performance deterioration in gas-turbines. One type of damage is blade surface roughening due to fouling, erosion, or corrosion. The present research examines the effect of surface roughening on the aerodynamics of turbine blades. A combination of experimental measurements and computations were used during the investigation.;Experimental measurements were conducted using a low-speed, large-scale cascade. Computations were made using a viscous/inviscid interaction approach. Experimental and predicted static pressure distributions, profile loss and flow deflection results were compared for design and off-design conditions with various configurations of surface roughness. Randomly distributed sand grains adhered to the surface of the blades were used to simulate surface roughening. The roughness height, the width of the roughness band, and the location of the band were varied.;The surface roughness significantly increased profile losses when present on the suction surface especially near the leading edge. It has only minor effects when present on the pressure surface and has little effect on flow turning in either case. The computational method gives good predictions of the effects of roughness on the pressure distribution, profile losses and flow turning. |
