CFD Based Design of a Centrifugal Compressor for Enhanced Range of Operation

Abstract Centrifugal compressors have become widely adopted due to their robust design, high efficiency, and broad operating range, making them essential across a wide array of applications. The largest application of radial compressors, by production volume, is in turbochargers for automotive applications, which require a wide operating range. Despite their advantages, including high efficiency and robust design, centrifugal compressors are susceptible to stall and surge during operation, making the design and optimization process highly complex and challenging. The present study aims to develop a compressor design that begins with a 1D mean line design approach and subsequently utilizes Computational Fluid Dynamics (CFD) for 3D analysis to optimize performance across a range of operating points. This process involves designing a turbocharger impeller based on a baseline compressor map and refining its performance to expand the operating range. The impact of volute geometry was also analysed, offering a comprehensive framework for centrifugal compressor design. The outcome of this research provides insights into the effects of key parameters such as trim, exit width, number of blades, and tip clearance on compressor performance. Through the current study, it was found that reducing trim improves surge margin, while a wider outlet width ratio resulted a lower outlet flow coefficient and greater flow deceleration. Also, increasing the number of blades reduced the impeller throat area, leading to a decrease in maximum flow rate. Additionally, increasing tip clearance was observed to cause higher blockage, potentially reducing the work input. This study aims to provide guidelines for the careful selection of compressor design parameters and modelling methodologies using CFD. The findings offer valuable insights for optimizing centrifugal compressor design and enhancing performance, ultimately resulting in a wider operating range.