Cavitation Performance of Constant and Variable Pitch Helical Inducers for Centrifugal Pumps: Effect of Inducer Tip Clearance
Cavitation Performance of Constant and Variable Pitch Helical Inducers for Centrifugal Pumps: Effect of Inducer Tip Clearance
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DOI：
10.1115/1.4044629
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发表时间：
2020-02
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影响因子：
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通讯作者：
E. Karakas;Hiroyoshi Watanabe;M. Aureli;C. Evrensel
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文献类型：
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作者：
E. Karakas;Hiroyoshi Watanabe;M. Aureli;C. Evrensel
研究了诱导轮叶顶间隙对离心泵汽蚀和非汽蚀性能的影响。螺旋诱导与恒定的间距和可变（渐进）间距被认为是。对每种诱导轮类型进行单级泵的计算流体动力学（CFD）模拟，以确定不同诱导轮叶尖间隙的空化（两相）和非空化（单相）性能。瑞利-普累塞特空化模型被用来理解气泡动力学的假设下，单一的流体进行没有热能传递的每个阶段之间。在一台装有变螺距诱导轮的离心泵上进行了汽蚀和非汽蚀工况下的试验研究。实验结果进行了比较，以验证所提出的数值模拟的准确性。采用3%水头差的净正吸入压头（NPSH）作为标准，以确定每个诱导轮配置的真实空化性能。结果表明，随着诱导轮叶顶间隙的增大，诱导轮叶顶处出现了过量的反泄漏和较大的旋涡回流。这会导致诱导轮内的压力损失，从而降低空化性能。此外，与恒定螺距情况相比，变螺距诱导轮几何形状的空化性能随叶尖间隙的变化更为明显。此外，诱导轮叶尖间隙对非空泡性能的影响被发现是最小的。
In this paper, the effect of the inducer tip clearance is studied to understand its impact on the cavitating and noncavitating performance of centrifugal pumps. Helical inducers with constant pitch and with variable (progressive) pitch are considered. Computational fluid dynamics (CFD) simulations of a single stage pump are conducted on each inducer type to determine the cavitating (two-phase) and noncavitating (single-phase) performance for varying inducer tip clearance. The Rayleigh–Plesset cavitation model is used to understand the bubble dynamics under the assumptions of single fluid undergoing no thermal energy transfer between each phase. Experimental tests are conducted on a pump with the variable pitch inducer to determine the true performance in cavitating and noncavitating operating conditions. Experimental results are compared to the simulations to validate the accuracy of the proposed numerical modeling. Net positive suction head (NPSH) with 3% differential head drop is used as a criterion to identify the true cavitation performance of each inducer configuration. It is found that, as the inducer tip clearance increases, excessive back leakage and larger vortex recirculation occur at the tip location. This results in pressure loss within the inducer and, consequently, degrades the cavitation performance. In addition, the change in cavitation performance with the tip clearance is much more evident for variable pitch inducer geometries as compared to the constant pitch case. Furthermore, the impact on the noncavitating performance of inducer tip clearance is found to be minimal.