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TECHNICAL PAPERS

# Linear Stability Analysis of the Effects of Camber and Blade Thickness on Cavitation Instabilities in Inducers

[+] Author and Article Information
Hironori Horiguchi

Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japanhoriguti@me.es.osaka-u.ac.jp

Yury Semenov

Institute of Technical Mechanics, National Academy of Science and National Space Agency of Ukraine, 15, Leshko-Popel’ St., Dniepropetrovsk, 49005, Ukrainerelcom@semenov.dp.ua

Masataka Nakano

Technical Development and Engineering Center, Turbo and Hydraulic Machinery Department, Ishikawajima-Harima Heavy Industries Co., Ltd., 1 Shin-nakahara, Isogo, Yokohaha, Kanagawa, 235-8501, Japanmasataka̱nakano@ihi.co.jp

Yoshinobu Tsujimoto

Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japantujimoto@me.es.osaka-u.ac.jp

J. Fluids Eng 128(3), 430-438 (Oct 25, 2005) (9 pages) doi:10.1115/1.2173291 History: Received July 25, 2004; Revised October 25, 2005

## Abstract

It has been shown by experimental and numerical studies that various cavitation instabilities occur in inducers for rocket engines when the cavity length exceeds about 65% of the blade spacing. On the other hand, it has been pointed out by an experimental study that the cavitation instabilities occur when the pressure gradient near the throat becomes small to some degree. The present study is motivated to examine the latter criterion based on pressure gradient for cavitation instabilities from the viewpoint of theoretical analysis. For this purpose, analyses of steady flow and its stability were carried out for cavitating flow in cascades with circular arc and plano-convex blades by a singularity method based on closed cavity model. It was found that the criterion based on the cavity length for the occurrence of cavitation instabilities is more adequate than the criterion based on the pressure gradient. It was also found that the steady cavity length and the stability of the flow in both cascades can be practically correlated with a parameter $σ∕[2(α−α0)]$, where $σ$ is a cavitation number, $α$ is an angle of attack, and $α0$ is a shockless angle of attack.

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## Figures

Figure 1

Figure 2

Figure 3

Figure 4

Strouhal number of destabilizing roots for the cascade with flat plate blades. C∕h=2, β=80deg

Figure 5

Strouhal number of destabilizing roots for the cascade with circular arc blades. C∕h=2, β=80deg, α=5deg: (a) t∕C=0.01(α0=1.42deg) and (b) t∕C=0.02(α0=2.85deg)

Figure 6

Strouhal number of destabilizing roots for the cascade with plano-convex blades, C∕h=2, β=80deg, α=5deg: (a) t∕C=0.01(α0=1.30deg) and (b) t∕C=0.02(α0=2.60deg)

Figure 7

Effect of the length of inlet duct for the Strouhal number in the cascade with flat plate blades; C∕h=2, β=80deg: (a) Strouhal number of modes I–V and (b) Strouhal number of modes I and II

Figure 8

Steady pressure distribution on the suction surface of a blade in the cascades with flat plate blades (t∕C=0) and circular arc blades at the onset of the rotating cavitation, C∕h=2, β=80deg, α=5deg: (a) t∕C=0, σ∕[2(α−α0)]=2.44, (b) t∕C=0.01, σ∕[2(α−α0)]=1.92, and (c) t∕C=0.02, σ∕[2(α−α0)]=1.51

Figure 9

The same as Fig. 8, for the cascades with plano-convex blades: (a) t∕C=0.01, σ∕[2(α−α0)]=1.96 and (b) t∕C=0.02, σ∕[2(α−α0)]=1.33

Figure 10

Figure 11

Figure 12

Pressure gradient on the suction surface of a blade at ξ=hsinβ in the cascade with flat plate blades; α=5deg: (a) C∕h=1,2,3(β=80deg) and (b) β=80,70,60deg(C∕h=2)

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