Rotordynamic Forces Acting on Three-Bladed Inducer Under Super-Synchronous/Synchronous Rotating Cavitation

Yoshida, Yoshiki; Eguchi, Masato; Motomura, Taiichi; Uchiumi, Masaharu; Kure, Hirotaka; Maruta, Yoshiyuki

doi:10.1115/fedsm2008-55135

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“…Under some conditions, the large cavity region may rotate more slowly than the inducer, and the resulting instability is called sub synchronous RC [17]. Asymmetric cavitation, in which cavity lengths are unequal on each blade, is known as a source of cavitation induced shaft vibration in turbomachinery [19]. AC is an important unstable cavi tation process.…”

Section: Introductionmentioning

confidence: 99%

Research on the characteristics under the condition of asymmetric cavitation in a centrifugal pump

Yuan

Zhou

et al. 2014

2014 ISFMFE - 6th International Symposium on Fluid Machinery and Fluid Engineering

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Major types of cavitation instabilities in hydraulic machi neries include cavitation surge (CS), rotating cavitation (RC), asymmetric cavitation (AC) and high-order instabil ities. Asymmetric cavitation, in which cavity lengths are unequal on each blade, is known as a source of cavitation induced shaft vibration in turbomachinery. In this paper, the internal flow characteristics and inlet and outlet pres sure pulsation characteristics of the centrifugal pump of asymmetric cavitation have been investigated through nu merical simulation and experimental method. [t could be found that asymmetric and uneven cavity volume distribu tion is resulted from rotor-stator interaction between im peller and volute tongue, and the uneven distribution of cavity volume between each blade also influence each other, which may induce the asymmetric cavitation. Clear corresponding relationship between the distribution of ca vity and the position of vortex in each blade channel can be found. It is obvious that the dominant frequency of pump inlet pressure fluctuation keeps at about 0.6 -0.8 times (about 30 -40 Hz) of the shaft frequency, and broadband pulsations distribute between 0 and 20 Hz at the condition of asymmetric cavitation. The generation of flexible vapor bubbles plays an important role in enhanc ing the buffering effect to the pump inlet liquid. Com pared to the effect of rotor-stator interaction between im peller and volute tongue, the collapse of vapor bubbles plays a dominant role to the pump inlet pressure fluctua tion in the condition of asymmetric cavitation. Meanwhile, the dominant frequency of pump outlet pressure pulsation is the blade passing frequency, and the generation and collapse of asymmetric cavity in each blade channel pro duced the broadband pulsation of pump outlet pressure under asymmetric cavitation.

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Section: Introductionmentioning

confidence: 99%