Experimental and Numerical Investigation of Pressure Fluctuation in a Low-Specific-Speed Centrifugal Pump with a Gap Drainage Impeller

Li Zhang,Wanhong Wang,Hong Xu,Weidong Shi,Ling Zhou,Yang Yang,Hui Li,Desmond Adair

doi:10.1155/2021/5571178

Li Zhang, Wanhong Wang + Show 6 more

Open Access

https://doi.org/10.1155/2021/5571178

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Abstract

In order to analyze the effect of impeller with different slot widths on the performance of the low-specific-speed centrifugal pumps, based on the impeller of a single-stage pump with the specific speed of 21, two gap drainage schemes with slot widths of 1.5 mm and 6.0 mm, slot diameter of 180 mm, and lap length of 5 mm were designed. Both experimental and numerical simulation methods were applied to compare the steady performance, which includes the head, efficiency, and the internal flow field distribution, and the unsteady pressure pulsation performance between new designed pumps and the original pump. The results show that gap drainage would cause a certain degree of head reduction, but a smaller slot width could achieve higher efficiency. Meanwhile, a reasonable open seam scheme can reduce the development of pressure pulsation, which provides experience and reference for the stable operation of low-specific-speed centrifugal pumps.

Highlights

Low-specific-speed centrifugal pumps are often used in low flow rate and high head occasions [1, 2]
The methods of numerical calculation and experiment have been applied to the research on the difference of pump performance, internal flow field, and pressure pulsation characteristic of three pump models, which included the original model, model 1 with 1.5 mm, and model 2 with 6.0 mm slot width at the diameter of 180 mm. e influence of slot width on the steady and unsteady characteristics of low-specific-speed centrifugal is analyzed, and the main conclusions are as follows: (1) Numerical calculations of the initial model head and efficiency agree well with the experimental results. e maximum errors of head and efficiency between numerical and experimental are at 1.4Qd, and the errors are 4.7% and 3.1%, respectively
(2) e gap drainage impeller has a great influence on the head of low-specific-speed centrifugal pumps, and the slot would cause a certain degree of head reduction. e head reduction goes up with the increase of the slot width; higher efficiency can be achieved with smaller slot width

Summary

Introduction

Low-specific-speed centrifugal pumps are often used in low flow rate and high head occasions [1, 2]. Yuan et al [21] employed the numerical simulation to analyze the inner flow field of a centrifugal pump impeller with splitter blade and obtained that the split has an effect on the stability of impeller outlet flow, the occurrence of the flow separation, and the structure of “jet-wake.”. Zhu and Chen [25] utilized the numerical and experimental investigation to compare the difference of the cavitation performance between the conventional and gap impeller, and they obtained that the structure of gap impeller can effectively suppress the generation of cavitation especially in large flow area. Zhang et al [26] adopted the numerical method to study the influence of a slot on the cavitation performance of the centrifugal pump and found that the slot can suppress the reverse flow and improve the cavitation performance at low flow rate, while causing a head decrease in the whole flow rate. A typical centrifugal pump with the specific speed of 21 was selected to study the effect of slot width on the performance and internal flow field of low-specific-speed centrifugal pump. e pressure pulsation at impeller outlet, volute tongue, and volute water cross position were monitored, and the time domain diagrams at these points were compared. is research provides reference for improving performance and stability of low-specific-speed centrifugal pump

Geometry and Numerical Methods

E Figure 1

Results and Analysis

Conclusions