前向多翼离心风机叶片尾迹和蜗壳二次流动的试验研究

对前向多翼式离心风机建立了性能及流场测试台位 性能试验及流场测试表明,性能试验重复性良好,曲线符合理论性能曲线.用粒子图像速度场仪技术对叶片尾迹区及蜗壳出口横截面上的二次流做了详细的变工况测量与分析.结果表明:叶片尾迹区脉动强度达20%～70%;在设计工况附近叶片尾迹影响区域小,在非设计工况下叶片尾迹影响区域大,尾迹区域占到蜗壳径向宽度的15%～25%,约是叶片弦高的2～3倍;在蜗壳横截面上明显存在二次流旋涡;沿着蜗壳旋出方向二次流对称分布,但是到达出口时,小流量下两侧旋涡结合成一个旋涡,大流量下两侧旋涡一直保持到蜗壳出口.

Experimental Study on the Blade Wake and Secondary Flow in Volute of a Forward Curved Multi-Blades Centrifugal Fan

A test rig system was built which can perform the performance and flow field measurement of a forward curved multi-blades centrifugal fan. A particle image velocimetry system was used to measure the secondary flow in the volute cross-section and the blade wake flow. The result shows that the fluctuation intensity of the wake flow reaches about 20%-70%. Near the designed working condition the effect area of the blade wake is small while the effect region increases under the off-design working condition. The radial width of the blade wake accounts for 15%-25% of the radial width of volute and is about 2-3 times of the blade chord height. The secondary flow vortex does exist in the cross section of the volute, which has relationship with the different working ability of the blade axial segment that results in a different blade outlet total pressure. Because of the back-to-back configuration of the double inlet fan, the secondary flow is symmetrically arranged along the profile curve of volute. When the flow reaches the volute outlet, however, the two secondary flow vortexes combine into one at a small flow rate while the two vortexes maintain till to the volute outlet at a large flow rate. .