A Multistage Body Force Model for Evaluating the Impact of Geometric Variations on the Aerodynamic Performance of a High-Pressure Compressor

Compressor blades in turbofan engines undergo geometric variations during operation. Either through active adaption measures, deterioration or operational loads, geometric differences from the design blade shape induce an alteration in engine performance. A dependable prediction of these effects therefore remains a major concern in engine design and operation. To assess the impact geometric variations impose on the respective components, bladed 3D RANS and URANS CFD simulation approaches are the most common. These, especially for multistage configurations, become increasingly costly and time consuming. Especially if multiple combinations of blade shape alterations in different rows of the compressor need to be considered, evaluation approaches with reduced complexity become increasingly beneficial. Therefore, this investigation proposes a Body Force Model based approach for the efficient evaluation of geometric variations in multistage high-pressure compressors. Based on an extensive re-engineering routine of an existing full scale high bypass turbofan engines high-pressure compressor, a substitute Body Force Model is derived and on- as well as off-design calculations are conducted. By comparing the Body Force Model results to the speed lines predicted by a bladed stationary 3D RANS CFD simulation, the suitability of the implemented loss, incidence, and deviation models is assessed. Finally, geometric variations in the rotor rows are introduced and their impact on integral parameters, such as efficiency, pressure ratio and mass flow rate are predicted. Again, a bladed CFD is utilized to assess the model’s prediction accuracy and to determine the suitability of a Body Force Model for the assessment of geometric variations in turbofan engine compressor components.