Numerical and Experimental Investigation of External Characteristics and Pressure Fluctuation of a Submersible Tubular Pumping System

Abstract

This paper presents an investigation of external flow characteristics and pressure fluctuation of a submersible tubular pumping system by using a combination of numerical simulation and experimental methods. The steady numerical simulation is used to predicted the hydraulic performance of the pumping system, and the unsteady calculation is adopted to simulate the pressure fluctuation in different components of a submersible tubular pumping system. A test bench for a model test and pressure pulsation measurement is built to validate the numerical simulation. The results show that the performance curves of the calculation and experiment are in agreement with each other, especially in the high efficiency area, and the deviation is minor under small discharge and large discharge conditions. The pressure pulsation distributions of different flow components, such as the impeller outlet, middle of the guide vane, and guide vane outlet and bulb unit, are basically the same as the measurement data. For the monitoring points on the impeller and the wall of the guide vane especially, the main frequency and its amplitude matching degree are higher, while the pressure pulsation values on the wall of the bulb unit are quite different. The blade passing frequency and its multiples are important parameters for analysis of pressure pulsation; the strongest pressure fluctuation intensity appears in the impeller outlet, which is mainly caused by the rotor-stator interaction. The farther the measuring point from the impeller, the less the pressure pulsation is affected by the blade frequency. The frequency amplitudes decrease from the impeller exit to the bulb unit.Processes 2019, 7, 949 2 of 11 impeller and the guide vane. These pulsations can sometimes be very severe and cause damage to the piping or other components in a pumping system, which may give rise to vibration [6][7][8][9], generate hydraulic noise [10][11][12], and affect the performance of the pumping system, thus affecting the stable operation of the pumping system. Therefore, the distribution of pressure pulsations in the pump needs to be studied to ensure the safe, efficient, and stable operation of the pumping station.With the development of computational fluid dynamics (CFD) technology, more scholars are using CFD to study complex flow fields in pumps [13][14][15], but the results of numerical simulation need to be verified by experimental data. Therefore, combining numerical simulation and experiments is more reliable. To ensure the safe and stable operation of pumping stations, many researchers are paying attention to the pressure pulsation and the unsteady flow inside the centrifugal pumps [16][17][18][19][20][21][22][23] and axial-flow pumps [24][25][26][27][28][29]. Studies on tubular pumps are relatively rare. Yang et al. [30] studied the pressure fluctuation of an S-shaped shaft extension tubular pumping system by CFD and experimentation, where the pressure fluctuations at 21 measurement locations in inlet and outlet passages were obtained and analyzed in...

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