Flow Characteristics in Plane S-type Axial Extended Tubular Pump

Abstract

【Objective】 The S-type axial extended tubular pump is a device widely used in various hydraulic engineering projects. The objective of this paper is to analyze the pressure pulsation characteristics and flow stability in the pump under different working conditions in low-lift stations. 【Method】 Three-dimensional full-channel numerical simulation is carried out with software CFX, and the turbulence model is selected as RNG k-ε. Fast Fourier transform (FFT) is used to process the pressure signal, and the flow data is visualized in the Ansys Post system. The flow characteristics, pressure pulsation characteristics and vorticity distribution characteristics in the pump unit under three typical conditions, 0.8 Qd, Qd and 1.2 Qd (Qd is the design flow condition) were analyzed. 【Result】 Flow pattern in the inlet of the channel is stable, and flow stability in the outlet of the channel is mainly affected by flow condition. The impeller's rotation serves as the excitation source of pressure pulsation in the pump, and there are high-order harmonics of blade frequency at the inlet of the impeller. The amplitude of high-order harmonics at the outlet of the impeller is small, and there are complex frequency components at the outlet of the guide vane, along with evident low-frequency pulsations. We also find that the flow vorticity in the inlet passage is zero, while the vorticity in the impeller chamber, guide vane chamber, and outlet passage is highly diverse. Due to the rotation disturbance of the impeller, the vorticity in the flow field in the impeller chamber and guide vane chamber is the largest. Under low flow condition, the difference in vorticity between the pump section and the outlet channel is the highest, while the vorticity decreases with increasing flow. This is consistent with the change of flow pattern in the pump device, thereby explaining, from an energy perspective, the reason for variation of the flow stability under different flow conditions. 【Conclusion】 Our results provide guidance for comprehending the mechanisms underlying flow characteristics and stability in the plane S-type pump device. They are helpful for engineering design.

Keywords

• plane s-type axial extension tubular pump
• vorticity
• pressure pulsation
• flow characteristics
• numerical simulation