Probabilistic analysis of meanline compressor rotor performance

Abstract

This thesis addresses variability in aerodynamic performance of a compressor rotor due to geometric variation. The performance of the rotor is computed using a meanline model that includes the effect of tip clearance blockage, calculated by assuming the tip leakage behaves like a wake in a pressure gradient and incorporating the effects of double leakage. The model is used to quantify performance variability of the rotor at design flow coefficient and near stall given typical variations in blade profile geometry, hub and casing diameters, and tip clearances. Monte Carlo simulation performed at both operating conditions shows that the coefficient of variation of pressure rise, loss coefficient, axial displacement thickness, and flow angle at the exit of the blade row is similar at high and low loading. Mean shifts are smaller at design than near stall, where the mean pressure rise and loss shift -0.4% and +0.6% from their respective nominal values. A parametric analysis using a response surface showed that near stall, tip clearance variation drives performance variation; the pressure rise and loss coefficient standard deviation drop by 26% and 20% when tip clearance variability is removed. At design, tip clearance variability is still important, but leading and trailing edge blade geometries play a larger role in driving performance variability.