Nonlinear Pre-deformation Method for Compressor Rotor Blade

Abstract

A cold compressor blade deforms elastically under aerodynamic and centrifugal loads during operation, transforming into a hot blade configuration. Blade deformation has a significant effect on the performance of compressor. A nonlinear pre-deformation method for compressor rotor blade was developed with consideration of the nonlinear features of blade stiffness and load which varies with blade configuration. In the blade profile design phase, the method can be used to compensate the aeroelastic deformation of the blade during operation. The adverse effects of blade deflection on compressor performance and structure can be avoided by the pre-deformation method. Due to the fact that the nonlinear method is sensitive to initial value, a load incremental method was applied to calculate initial blade deformation to stabilize and accelerate the pre-deformation method. The developed method was used to predict the manufactured configuration of the Stage 37 rotor blade. The variation rules of aerodynamic and structure parameters of the pre-deformed blade were analyzed under off-design conditions. Results show that the developed method ensures that under the design condition there was a good match between the actual blade configuration during operation and the intended design blade profile. The blade untwist angle of pre-deformed blade could be 0° at design point. Meanwhile, the tip clearance only decreased 0.2%. When the working speed was faster than 80% design speed, the performance of the pre-deformed blade agreed with that of the design blade. However, the mass flow rate and the total pressure ratio of the pre-deformed blade were lower at low speeds.