Effect of Splitter Blades on Performances of a Very Low Specific Speed Pump

Abstract

The usage of splitter blades to enhance the performances of low specific speed pumps is common practice. Based on experimental and numerical studies, the influence of the addition of one and two splitter blades is investigated on a very low specific speed pump to assess their impact not only on the performance characteristics but also on the losses in all pump domains. First, the main characteristic curves are discussed and it is shown that the usage of splitter blades enhances the head of the pump while not impairing its efficiency. Secondly, a detailed analysis of the losses in the pump reveals that splitter blades improve the flow in all parts of the pumps, but the volute. The flow at the impeller outlet shows that splitter blades largely benefit the slip factor and discharges a more blade-congruent flow in the volute. However, higher absolute velocity at the outlet of the impeller with splitter blades increases friction at the volute wall, as confirmed by the average wall shear stress in the different tested cases.

Effect of blade layout on performance of low specific speed pump operating in turbine mode

“…As shown in figure 11, adding the splitters helps the flow to be more blade-congruent with less secondary flow. The side conclusion is, that inclusion of splitters has not such significant advantage in PaT as was expected and as was reported for pump mode [9].…”

“…The physical model of pump, test facility, used equipment and uncertainties are well described in PhD thesis of L. Chabannes [9], thus only brief description is presented hereafter. While, the volute and impellers were newly designed, the casing with driveshaft, seal and bearings were adopted form existing pump with similar parameters.…”

“…Based on previous CFD simulations of this particular pump [12,9,10] and other studies dealing with simulation of low specific speed pump [13], the application of low-Re turbulence model is prioritised over the high-Re turbulence model with wall function, such is k − ϵ model. For simulation of low specific speed pump the prediction of flow in the near wall region and onset of separation is important.…”

“…From authors knowledge, there is none or only very limited number of studies of such low specific speed centrifugal pump operating in turbine mode. Additionally, based on previous work of Chabannes [9] it is possible to study effect of different impeller layouts on turbine mode performance.…”

Hydraulic Optimization and Experimental Measurement of Low Specific Speed Centrifugal Fire Pump

“…To obtain the optimum mass dimensional parameters for centrifugal fire pumps, Vasiljeva et al (2020) developed an optimized mathematical model that enables centrifugal pumps for fire-fighting to be designed in such a way that the weight of the pump is minimized while ensuring high reliability. To attain centrifugal fire pumps with excellent performance, splitter blades (Shi et al 2009;Yuan and Yuan 2017;Rosa Emerick 2020;Namazizadeh et al 2020;Chabannes et al 2021;Adu et al 2021) were used to change the internal flow characteristics of low-specific-speed centrifugal fire pumps, and Yang et al (2017) used an increased flow rate design method. Zhang et al (2020) used NSGA-II and RBF hybrid algorithms to optimize the efficiency and head of the centrifugal pump, and Xu et al (2016) used the orthogonal optimization method to select parameters, such as blade wrap angle, blade inlet, and outlet angle of a centrifugal pump to optimize the efficiency and cavitation performance of the centrifugal pump.…”