Enhanced aerodynamic performance of irregular centrifugal fan casings through parametric and level-set topology optimization

The geometric configuration of a fan casing plays a crucial role in determining the airflow rate and power consumption of centrifugal fans. This study explores the optimization of an irregular fan casing used in an automotive engine cooling module, employing two distinct optimization approaches: parametric optimization and level-set topology optimization. Additionally, flow field characteristics and entropy generation analysis were conducted to reveal the underlying mechanisms of optimization methods. Experimental validation was performed for both optimization techniques. The results demonstrate significant performance improvements with both methods; however, topology optimization, offering greater geometric flexibility, yielded superior results. Compared to the original casing, the total pressure loss coefficient of the parametric-optimized casing decreased by 3.6 %, while the that of the topology-optimized casing decreased by 7.3 %. From the flow field perspective, both casings significantly improved the flow field, reducing the range of vortices and increasing the airflow output. However, due to the increased airflow and more intense flow conditions, entropy generation of the flow field within the optimized casings also increased, leading to higher power consumption of the fan module. Experimental results further indicate that the optimized casings achieved higher exhaust volumes per unit power consumption, with the parametric-optimized casing showing a 0.6 % improvement and the topology-optimized casing a 3.8 % improvement over the original. These findings provide guidance into the design optimization of irregular fan casings.