|
|
|
| Pressure pulsation characteristics in down-scaled high specific speed centrifugal pump in cavitating state |
| WANG Kaili1, LI Hong1*, SHEN Zhenhua2 |
| 1. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. Grundfos(China)Investment Co. Ltd., Beijing 100190, China |
|
|
|
|
Abstract The down-scaled model pump of a high specific speed centrifugal pump was obtained by using the affinity laws for centrifugal pumps. It turned out that the performance curve of the model pump is similar to the original scale pump based on experiments and numerical simulations, and the model pump can replace the original pump for experimental study. Based on the RNG k-ε turbulence model, the incompressible time-average N-S equations of the fluid flow in the pump model were solved by SIMPLEC method. The hydraulic, cavitation performance and pressure pulsation characteristics of the pump were obtained under different operating conditions beads on steady and transient numerical simulations of the flow field in the pump. The accuracy of simulation was validated by comparing the simulated results with the experimental observations. In terms of simulation, the largest pressure pulsation amplitude is seen at the tongue at the rated flow rate. The dominant frequencies of pressure pulsation at each monitoring point under different working conditions are blade passing frequency. The tongue experiences the largest pressure fluctuation, but the impeller inlet is subject to the smallest pressure pulsation. The pressure pulsation amplitude is the smallest under the rated flow rate condition, but significantly increased under off-design conditions. Through the transient numerical simulation at different stages of cavitation, it is found that from non-cavitation to severe cavitation, the pressure pulsation characteristic in frequency domain on the tongue and at the outlet remains unchanged under different working conditions. Specially, the pressure pulsation amplitude decreases with cavitation deve-lopment, and the dominant frequency of the pulsation is the blade passing frequency. And with extending cavitation degree, the high frequency components in the pressure pulsation become rich, and the dominant frequency at each monitoring point drops off significantly. These outcomes can be used as the basis for judging cavitation inception.
|
|
Received: 22 February 2019
|
|
|
|
|
|
|
