One of the problem areas of fluid flow in the turbomachine is its inlet region, manifested by flow distortions due to the induced fluid swirl accompanied by improper flow incidence onto the impeller. Further, the hub forms one of the main components of many of the turbomachines and it is found that there has not been significant study on geometrical modifications of the same in centrifugal fans for augmented performance. This is partially due to designers trying to reduce the cost of the overall machine. There is a scope for detailed parametric study and the present work involves an exploration of flow behavior by parametric variation of hub geometry in terms of both its shape and size. Experiments are carried out in order to determine the importance of hub with different size and shapes. The geometric models of hemi-spherical and ellipsoidal hubs are considered for the analyses in the present study. An optimized ellipsoidal hub configuration is found to yield a relative improvement of about 7.5% for head coefficient and 7.7% increase in relative theoretical efficiency over the hub-less base configuration. Finally, correlations are developed for the optimized hub shape configurations. It is revealed from experimental analysis that hub plays a vital role in streamlining the flow at the inlet to the centrifugal fan and augments its performance.

中文翻译：

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实验研究和经验关系对创新型轮毂几何形状对离心风机性能增强的影响

涡轮机中的流体流动的问题区域之一是其入口区域，其表现为由于引起的流体旋流以及伴随不适当的流入射到叶轮上而引起的流动变形。另外，轮毂构成许多涡轮机的主要部件之一，并且发现，对于用于提高性能的离心风扇中的轮毂的几何变形，还没有进行大量研究。这部分是由于设计人员试图降低整体机器的成本。有一个详细的参数研究范围，而本工作涉及通过轮毂几何形状和尺寸方面的参数变化来探索流动行为。为了确定不同尺寸和形状的轮毂的重要性，进行了实验。在本研究中考虑了半球形和椭圆形毂的几何模型。与无轮毂的基本配置相比，发现优化的椭圆形轮毂配置可产生约7.5％的水头系数相对改进，相对理论效率提高7.7％。最后，为优化的轮毂形状配置开发了相关性。从实验分析中可以看出，轮毂在简化离心风机入口处的气流并增强其性能方面起着至关重要的作用。为优化的轮毂形状配置开发了相关性。从实验分析中可以看出，轮毂在简化离心风机入口处的气流并增强其性能方面起着至关重要的作用。为优化的轮毂形状配置开发了相关性。从实验分析中可以看出，轮毂在简化离心风机入口处的气流并增强其性能方面起着至关重要的作用。