In this work, the unsteady Reynolds-averaged Navier–Stokes (URANS) and three hybrid Reynolds-averaged Navier–Stokes-large eddy simulation (RANS-LES) models are employed to resolve the vortical flows in a typical single-stage side channel pump, to evaluate the suitability of these advanced turbulence models in predicting the pump hydraulic performance and unstable swirling flows. By the comparison of the overall performance, it can be observed that the results obtained by scale-adapted simulation (SAS) are closer to test data than shear stress transport (SST), detached eddy simulation (DES) and filter-based model (FBM). Simultaneously, the distribution of axial velocity on the plane near the interface is used to describe the position and intensity of internal fluid exchange between impeller and side channel. It is obvious that the intensity of mass flow exchange is strong near the inner and outer edges. Then, the vortex core region illustrates that the vortex is easily produced near the interface due to internal fluid exchange. Finally, the evolutions of circumferential in-plane vortical structures are presented to further account for the process of fluid exchange and the main vortex flows. It reveals that the recirculation flow presents a strong instability during 6–7 blade pitches as the fluid enters into the impeller and the flow is stable in downstream 7–8 blade pitches. Besides, the flow turns to be unsteady near outlet affected by the sudden change of fluid direction. This work could provide some suggestions for the choice of appropriate turbulence model in simulating strong swirling flows.

This paper seeks to predict the performance of the side channel pump by considering the influences of different wrapping angles. Firstly, three pump cases 1, 2 and 3 are modeled with wrapping angles 15°, 30° and 45°, respectively. Secondly, different physical parameters comprising exchanged mass flow, pressure and velocity distributions are plotted at the best efficiency point (Q_BEP) to analyze the internal flow characteristics. Since the flow exchange times depend on the size of the wrapping angle, the size of the wrapping angle has significant effects on the pump head performance. Case 1 with the smallest wrapping angle recorded the largest head improvement at all operating conditions compared to case 2 and case 3. Case 1 at Q_BEP attained a head coefficient increase of about 9.8% and 38.6% compared to that of case 2 and case 3, respectively. However, the size of the wrapping angle had a slight effect on the pump efficiency; thus, case 1 still predicted a marginal increase in efficiency compared to case 2 and case 3 at all operating conditions. Lastly, the numerical simulations were validated with experimental data after manufacturing pump case 2.

Hydropower has been the leading renewable source and cheapest ways to generate electrical energy in the world. In recent years, there has been a major upsurge in the hydropower development because of the use of pump as turbine (PAT). However, the operational reliability of a PAT is greatly affected by the unsteady flow fields; therefore, it is important to examine the unsteady flow behavior which can be used as a reference to reduce the noise, vibration, and cavitation performance for centrifugal pumps working as turbines. Thus, the objective of this study was to evaluate the unsteady flow fields by analyzing the distribution of the pressure pulsations using both numerical and experimental measurements in a PAT operating in pump mode. Firstly, the three‐dimensional (3D) unsteady flow equations were solved using SST k‐ω turbulence model during the numerical calculations. Secondly, the numerical results of the hydraulic pump performance were validated by the experimental measurements for numerical accuracy. Lastly, pressure transducers are positioned at certain monitoring points to measure the pressure in the PAT investigated. The numerical and experimental results show that the main frequency of the pressure pulsation is equal to the blade frequency, and as it deviates from the design operating condition, the magnitude of pressure pulsation intensifies. Furthermore, the impeller eye marked the lowest pressure coefficients especially at the design condition and makes it highly susceptible to cavitation. High pressure coefficients were obviously seen at the pressure side on the blade surface closer to the trailing edge at all studied operating conditions. Meanwhile, the rotor‐stator interaction generated the highest pressure pulsation distribution at the volute tongue. Thus, modification of the volute tongue is an optimal approach of reducing the pressure pulsation intensity in the volute and pump as a whole.

Due to the centrifugal effect of the radial impeller, side channel pumps are a kind of regenerative pumps that provide high head at low flow rate. The geometry of the impeller affects flow patterns and energy conversion directly, greatly influencing the performance of side channel pumps. To investigate the effect of blade profile for suction side on the performance of a side channel pump, three different base angles of 10°, 20°, and 30°, respectively, on the blade suction side were discussed and analyzed both with numerical and experimental methods. The hydraulic performance, exchange mass flow, and velocity vectors were discussed in detail. The numerical work was validated by the comparison between the simulated result and tested result. The results show that the hydraulic performance of the impeller with 30° angle is the best one of the three impellers, especially for head performance. The evaluation method based on exchanged mass flow also confirms that the performance of the side channel pump can be improved by increasing the angle on the suction side of the blade. In addition, the radial vortex on the impeller flow passage has negative effect on the performance of the side channel pump. However, the axial vortex among the impeller and side channel directly affects the energy conversion and has a beneficial effect on the performance of the pump. The results could be used to modify the design models and conclude the effect of blade shapes on the performance of a side channel pump.