Influence of Impeller Gap Drainage Width on the Performance of Low Specific Speed Centrifugal Pump

Abstract

The centrifugal pump is one of the most important pieces of energy-consuming equipment in various hydraulic engineering applications. This paper takes a low specific speed centrifugal pump as the research object. Based on the research method combining numerical calculation and experimental verification, the influence of the gap drainage structure on the performance of the low specific speed centrifugal pump and its internal flow field distribution were investigated. The flow field inside the low specific speed centrifugal pump impeller under different gap widths was studied. The comparison between the numerical calculation results and the experimental results confirms that the numerical calculations in this paper have high accuracy. It was found that the gap drainage will reduce the head of the low specific speed centrifugal pump, but increase its hydraulic efficiency. Using a smaller gap width could greatly improve the performance of the low specific speed centrifugal pump on the basis of a slight reduction in the head. The high-pressure leakage flow at the gap flows from the blade pressure surface to the suction surface can effectively suppress the low-pressure area at the impeller inlet. The flow rate of the high-pressure leakage flow increases with the gap width. Excessive gap width may cause a low-pressure zone at the inlet of the previous flow passage. These results could serve as a reference for the subsequent gap design to further improve the operating stability of the low specific speed centrifugal pump.

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

“…The general performance and physical limitations of LSS pumps have been investigated by Kurokawa [6] and Olimstad [7]. Special design has also been proposed by Klas [8,9] where thick trailing edge replaced classic blading, or more recently by Wei [10] and Yang [11] who tested slit impeller blades on a pump with a specific speed n q = 5.7. Nonetheless, the most common solutions for LSS pumps is the addition of splitter blades to the impeller, to raise the pressure developed by the impeller as extensively studied in references [12][13][14][15][16][17], where generally variations of a splitter blade position in the impeller passage is studied for pump optimization.…”

Numerical investigation of unsteady pressure pulsation characteristics in an ultra-low specific-speed centrifugal pump as a turbine

“…In the turbulent transport equation, the unsteady term is a second-order difference, and the convection term is an upwind difference. Considering the factors such as calculation cost and calculation accuracy, the SST k-ω model is finally selected as the turbulence model (Han et al, 2021;Wei et al, 2021).…”

Performance Optimization of Slotted Blades for Low-Specific Speed Centrifugal Pumps

“…Ignoring smaller magnitudes, simplify equation (21) to From equation (22c), we can get the following result: the pressure p of the fuid boundary layer does not change along the y direction. Tis indicates that the fuid disturbance is caused by a pressure change in the x-axis direction: during fow channel difusion, there is a negative pressure gradient in the x-axis direction, that is, zp/zx < 0 in equation (22b).…”

“…Currently, some scholars have studied the relationship between the shape of the slit vane and the performance of centrifugal pumps by using orthogonal tests, but they are not very comprehensive [19,20]. Zhang et al and Wei et al investigated the efect of slot width on drainage performance [21,22]. Te study found that slot drainage will reduce the head, but it will increase its hydraulic efciency.…”