Abstract
A large-scale, vaned-voluted centrifugal pump can be applied as the key component in water-transfer projects. Pressure pulsation will be an important factor in affecting the operation stability. This paper researches the propagation and spatial distribution law of blade passing frequency (BPF) and its harmonics on the design condition by numerical simulation. Experimental and numerical monitoring is conducted for pressure pulsation on four discrete points in the vaneless region, which shows that the BPF is dominant. The pulsation tracking network (PTN) is applied to research propagation law and spatial distribution law. It provides a reference for frequency domain information and visualization vaned diffuser. The amplitude of BPF and its harmonics decays rapidly in the vaneless region. BPF and BPF’s harmonics influence each other. BPF has local enhancement in the vaneless region when its harmonics attenuate. In the vaned diffuser, the pulsation amplitude of BPF attenuates rapidly, but the local high-pressure pulsation amplitude can be found on the vane blade concave side because of obstruction and accumulation of the vaned diffuser. In the volute, the pulsation amplitude of BPF is low with the decelerating attenuation. This study provides an effective method for understanding the pressure pulsation law in turbomachinery and other engineering flow cases.
Highlights
Large scale centrifugal pumps suit both large flow rate and high head requirements.When applying a large-scale centrifugal pump in liquid delivering, the operation stability is very important due to the contained strong flow energy and its pulsations
In axial-flow pump cases, the maximum pressure pulsation may be upstream to the impeller inlet, and in vaned diffuser channels it will mainly be with the blade passing frequency (BPF)
The attenuation and propagation laws of pressure pulsation amplitude are somehow indicated, which provides a new understanding of pulsation flow driven by rotor-stator interaction in the vaneless region, vane channels, and downstream diffusers
Summary
Large scale centrifugal pumps suit both large flow rate and high head requirements. When applying a large-scale centrifugal pump in liquid delivering, the operation stability is very important due to the contained strong flow energy and its pulsations. In axial-flow pump cases, the maximum pressure pulsation may be upstream to the impeller inlet, and in vaned diffuser channels it will mainly be with the BPF. The impeller blade distributions of a double-suction centrifugal pump have a significant impact on the amplitude of pressure pulsation. The blade-excited frequencies are deeply focused towards the downstream region of the impeller, which covers vanes, volute, and cut-water. The pulsation amplitude, phase, dominant frequencies, propagation, and attenuation are analyzed in detail. The generation, propagation, and attenuation of blade-excited frequencies are numerically investigated It gives a completely new view of the turbulent flow inside the pump and provides new ideas for solving the operation stability problems in pump and pumping station engineering cases
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