The Effect of Ultrapolish on a Transonic Axial Rotor

Back-to-back testing was done using NASA fan rotor 67 in the Glenn Research Center W8 Axial Compressor Test Facility. The rotor was baseline tested with a normal indus- trial root-mean-square (RMS) surface finish of 0.5 lm to 0.6 lm (20 microinches to 24 microinches) at 60, 80, and 100% of design speed. At design speed the tip relative Mach number was 1.38. The blades were then removed from the facility and ultrapolished to a surface finish of 0.125 lm (5 microinch) or less and retested. At 100% speed near the design point, the ultrapolished blades showed approximately 0.3% to 0.5% increase in adi- abatic efficiency. The difference was greater near maximum flow. Due to increased relative measurement error at 60 and 80% speed, the performance difference between the normal and ultra-polished blades was indeterminate at these speeds.

William B. Roberts
Airfoil Technologies International and Flow Application Research,
Freemont, CA 94539 e-mail: bbclipper@hotmail.com

Scott A. Thorp
National Aeronautics and Space Administration, Glenn Research Center,
Cleveland, OH 44135 e-mail: Scott.A.Thorp@nasa.gov

Patricia S. Prahst
AP Solutions,
Solon, OH 44135 e-mail: Patricia.S.Prahst@nasa.gov

Anthony J. Strazisar
National Aeronautics and Space Administration, Glenn Research Center,
Cleveland, OH 44135 e-mail: Anthony.J.Strazisar@nasa.gov