Experimental Study of Shaft Vibration Caused By the Clouds of Cavitation in Backflow Vortices

Hashimoto, Tomoyuki; Shimagaki, Mitsuru; Nakamura, Noriaki; Nagaura, Katsuji; Hasegawa, S.

doi:10.2514/6.2007-5541

Cited by 2 publications

(2 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, this hypothesis cannot explain the increasing the 𝑓 𝑐𝑎𝑣 as 𝜎 decreased, since the propagation velocity of backflow vortex in rotational frame on inducer to the direction opposite to the inducer rotation becomes faster due to the reduction of the swirling radius of backflow vortex as the flow rate decreases [20]. Although Hashimoto reported that the similar shaft vibration with a component of 2.5𝑓 𝑁 is caused by the backflow vortices moving into the inducer blade pass [7], the difference between this phenomenon and instability which we found is that there is no mode transition. In other words, shaft vibration found by Hashimoto shows a jump in the dominant frequency from 2.5𝑓 𝑁 to 5.4𝑓 𝑁 over time, while ours shows a continuous frequency change.…”

Section: Observation Of Cavitation In the Occurrence Of The Instabilitymentioning

confidence: 96%

See 1 more Smart Citation

New type of cavitation instability with peculiar frequency characteristic in liquid rocket inducer

Tamura,

Kawasaki,

Iga

2024

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

In a liquid rocket turbopump with low pressure and thin wall tanks, cavitation inevitably occurs at the inducer which is installed at the inlet of the turbopump. The cavities at each blade oscillate periodically, and the turbopump sometimes becomes unstable, called cavitation instability. Rotating cavitation is one of the common types of cavitation instability, in which the cavities at each inducer blade oscillate respectively and appear to propagate from blade to blade. However, the new type of cavitation instability which does not follow the conventional principle has been observed in our experiment with an inducer. Converting the frequency in the inertial frame to that in the rotational frame and organizing it in the cavitation number, it was found that the frequency of unsteady cavitation increases as the cavitation number decreases, and this is the peculiar point of this instability. Additionally, during the cavitation instability, a few numbers of backflow vortex cavities were observed and moved sub-synchronously from blade to blade. In addition, the tip leakage vortex cavitation on each blade also propagates like sub-synchronous rotating cavitation but in different propagation speed from that of the backflow vortex cavities. As a result, it was supposed that the new instability is one of the types of sub-synchronous rotating cavitation related to backflow vortex cavitation, tip leakage vortex cavitation, and interaction between cavity propagation and inducer blade.

show abstract

Section: Observation Of Cavitation In the Occurrence Of The Instabilitymentioning

confidence: 96%

“…For example, backward rotating cavitation, in which the propagation direction of cavity is actually opposite of the direction of inducer rotation [6]. Furthermore, Hashimoto reported that the shaft vibration caused by cavity clouds of backflow vortex occurred after head breakdown [7].…”

Section: Introductionmentioning

confidence: 99%