高扬程潜水排污泵叶轮和蜗壳的匹配优化与试验

为提高高扬程潜水排污泵的性能,该文基于数值模拟、粒子成像测速(particle image velocimetry,PIV)测量和外特性试验并重的研究方法,以比转速为60的高扬程排污泵为研究对象,针对具有超厚叶片的叶轮与3种不同基圆直径的蜗壳进行了匹配优化。数值计算结果表明,具有超厚叶片的高扬程潜污泵蜗壳基圆直径对泵性能影响较大,当其与叶轮直径比D3/D2=1.13时,泵额定点的效率和扬程下降值均小于1%,但当D3/D2增大至1.19时,泵最高效率下降了3.3%;超厚叶片与蜗壳的匹配将直接决定泵内部流场特征,当D3/D2=1.01时,泵内部压力脉动和非定常径向力的峰峰值为D3/D2=1.13时的3倍左右,当D3/D2大于1.13时,其峰峰值变化较小。试验结果表明,兼顾考虑泵的外特性和内流场,方案B(D3/D2=1.13)具有陡降的流量-扬程曲线和饱和轴功率特性,最大轴功率不超过45kW,比国标规定的55kW小10kW,降低了生产成本。泵的高效区范围宽,在设计点泵效率达到71.80%,比国家标准高10.8个百分点;3个超厚叶片形成的3个通道,最大可通过颗粒直径为40mm的固体颗粒。PIV测量结果表明,在较大的流量范围内,叶轮内流场稳定,未出现不良流动现象,且此时泵内的压力脉动和径向力较小。该研究可为"高效率、无过载、无堵塞"的高扬程潜水排污泵的设计研究提供新的思路和实践指导。

Experiment and impeller and volute matching optimization of high-head submersible sewage pump

Abstract: In order to improve the sewage pump performance, the high-head sewage pump with the specific speed of 60 was investigated in this paper based on the methods of numerical simulation, particle image velocimetry (PIV) measurement and performance test. Matching of high-head sewage pump impeller with extra-thick blades and three volutes with different base circle diameters was optimized. Steady numerical results show that the volute base circle diameter D3 has greater impact on the hydraulic efficiency of the impeller with extra-thick blades. The base circle diameter of volute has smaller impact on the efficiency and head when the ratio D3/D2 of the base circle diameter of volute and impeller diameter is less than 1.13, while the efficiency decreased by about 3.3% when the ratio D3/D2 increased to 1.19 because of the increasing circulation losses in the volute. Unsteady simulation of impeller and volute coupling flow field show that extra-thick blade and volute matching will directly affect the flow field in pump, and the peak-to-peak value of pressure pulsation and unsteady radial force the of case A (D3/D2=1.01) is about three times that in case B (D3/D2=1.13), while the reduction of the peak-to-peak amplitude is very small when the ratio is greater than 1.13. The test results show that case B (D3/D2=1.13) has good performance and steady flow field with a steep drop curve of Q-H and saturated shaft power. The maximum value of shaft power is less than 45 kW compared with the national standard 55 kW, so the cost of production will be reduced. The efficiency of case B in design condition is 71.80% which is 10.8% higher than the national standard, and its amplitude of pressure pulsation and unsteady radial force are small. Three channels in impeller are formed by three extra-thick blades, so the maximum solid particle diameter of 40 mm could pass from it. PIV experimental results show that the flow field in the impeller is stable in a large range of flow rate without flow separation and backflow.