Influence of Clearances in Variable Guide Vanes and Stators on the Performance of a Multi-stage Compressor and Its Flow Control

In pursuit of enhanced accuracy in the performance prediction and optimization of high-load compressors, this study emphasizes the significance of empirically measured clearance values associated with variable guide vanes and stators in engineering applications. Utilizing these empirical data, we conduct a refined modeling approach for the variable guide vanes and stators. A comprehensive three-dimensional numerical simulation methodology is employed to examine the impact and underlying flow mechanisms of the adjustable blades with clearances in a nine-stage compressor, concurrently optimizing the positional parameters of the clearances to augment the aerodynamic performance of the compressor. The findings of this investigation reveal that the omission of clearances and platform geometry of adjustable blades in numerical simulations can lead to an overestimation of both maximum flow rates and the overall stability margins. Driven by the pressure differential between the suction and pressure sides, clearance leakage flow is generated at the leading edge of the end wall of adjustable blades, exacerbating flow separation in the end wall corner region and potentially resulting in corner stall phenomena. By adjusting the platform of the adjustable stators, which experience corner stall predominantly, the leading edge separation resulting from the interaction of the flow near the end wall and the leakage flow from the leading edge clearance is mitigated. Consequently, the maximum flow rate of the compressor is increased by approximately 0.48 kg/s, the overall stability margin is enhanced by approximately 7.52%, and the peak efficiency experiences an improvement of about 0.4%.