On low-frequency unsteady phenomena caused by cavitation in hydroturbines

International Scientific and Practical Conference: Water Power Energy Forum 2018

Kuibin, P.A.^1 ; Zakharov, A.V.^2

Kutateladze Institute of Thermophysics SB RAS, 1 Lavrentyev ave., Novosibirsk

630090, Russia^1

PJSC Power Machines LMZ, Sverdlovskaya nab., 18, St.-Petersburg

195009, Russia^2

关键词: Cavitation cavities;    Cavitation compliance;    Characteristic equation;    Destabilizing effect;    Instability mechanisms;    Oscillation increment;    Unsteady phenomena;    Vorticity distribution;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/288/1/012100/pdf
DOI  :  10.1088/1755-1315/288/1/012100

来源: IOP

【 摘 要 】

When hydroturbines operate at part load or over load, intense pressure and vibration pulsations may occur. One of the instability mechanisms is due to the presence of a cavitation bubble (or cloud) behind the runner. Chen et al. [1] the phenomenon is modeled using the concept of cavitation compliance. They demonstrated the destabilizing effect of the diffuser and swirl. In the present work, the influence of two factors on the coefficients of the characteristic equation, whose solution yields natural frequencies and oscillation increments, is revealed. They are the vorticity distribution and the size of the cavitation cavity behind the runner. It is shown that the effect of swirl on stability is much smaller than that described in [1] and rapidly decreases with the growth of cavitation bubble size.