Unsteady flow structure and its evolution in a low specific speed centrifugal pump measured by PIV
Unsteady flow structure and its evolution in a low specific speed centrifugal pump measured by PIV
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DOI：
10.1016/j.expthermflusci.2018.04.013
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发表时间：
2018-10
影响因子：
3.2
通讯作者：
Ning Zhang;B. Gao;Z. Li;Dan Ni;Q. Jiang
中科院分区：
文献类型：
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作者：
Ning Zhang;B. Gao;Z. Li;Dan Ni;Q. Jiang
离心泵内部复杂的流动结构所产生的强烈的流体动力相互作用对泵的稳定运行是不利的。基于粒子图像测速技术（PIV），对低比转速离心泵内的流动结构进行了详细的测量。重点研究了蜗壳舌区的复杂流动结构，在此区域出现了强烈的动静干涉。结果表明：在低于额定工况下，叶片出口处出现典型的射流-尾迹流态，射流-尾迹区的拐点位于叶片通道中心。在高流量下，由于高动量流体集中在叶片吸力面，射流-尾迹流态不明显。在泵内，在高流量下，在叶片压力侧和吸力侧上捕获了几个典型的涡量面（正涡量面和负涡量面），而在低流量下，由于分离和反向流动结构的出现，叶片吸力侧上的负涡量面消失。当涡面从叶片尾缘脱落时，会撞击到蜗舌上，造成切割和变形。在不同流量下观察到三种典型的相互作用模式，并且涡舌对涡面的切割效果强烈依赖于局部绝对速度分布。在高流量下，切割作用更为显著，整个涡面（正、负）都将被蜗舌切割撕裂。
The intense fluid-dynamic interaction associated with the complex flow structure in the centrifugal pump is detrimental to the stable operation of the pump. Based on the particle image velocimetry (PIV) measuring technique, flow structures in a low specific speed centrifugal pump are measured and presented in detail. Emphasis is laid upon the complex flow structures around the volute tongue region, where intense rotor–stator interaction appears. Results show that the typical jet-wake flow pattern at the blade outlet is observed for flow rates lower than the nominal working condition, and the inflection point of the jet-wake region is found to be at the center of the blade channel. At high flow rate, the jet-wake flow pattern is not apparent due to the high momentum fluid concentrating on the blade suction side. Within the pump, several typical vorticity sheets (both positive and negative) are captured on the blade pressure and suction sides at high flow rates, while at low flow rates, the negative vorticity sheets on the blade suction side disappear due to the separated and reverse flow structures occurring. When the vorticity sheet sheds from the blade trailing edge, it would impinge on the volute tongue with subsequent cutting and distortion. Three typical interacting modes are observed at different flow rates, and the cutting effect of the volute tongue on the vorticity sheet is dependent strongly on the local absolute velocity distribution. At high flow rates, the cutting effect is more significant, and the entire vorticity sheets (positive and negative) would be cut and torn by the volute tongue.