研究结果表明：通过优化有效降低了因二次流漩涡、风机蜗舌结构、尾流-射流和正冲角等造成的能量损失，提高了离心通风机性能。

The results show that the performance of optimized fan is improved by lowering the energy loss which caused by the secondary flow vortex, the volute tongue, the wake-jet and the angle of attack.

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因此，提出了一种通过改善蜗舌附近压力区的均匀性的、新的变螺旋角蜗壳设计方法。

Therefore a new design method with varying spiral angles of volute was proposed by means of focus on improving the uniformity of pressure field near the tongue of the volute.

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插角舌设计。

Gusseted tongue design.

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