Mechanism of Propagation Direction of Rotating Cavitations in a Cascade

Iga, Yuka; Yoshida, Yoshiki

doi:10.2514/1.49454

Cited by 17 publications

(16 citation statements)

References 18 publications

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“…On the other hand, at a = -3G, rotating-stall cavitation (R-stall C) occurs in some cases in the relatively high-σ region around σ = 0.15. In our previous study, we verified that R-stall C occurs at a high-angle-of-attack, low-flow-rate condition [5] . Therefore, the cavity thickness or the oscillation in the thickness direction is thought to be promoted by the influence of axial upstream acceleration, and the flow field becomes similar to that of a high-angle-of-attack condition.…”

Section: Cavitation Instabilitiesmentioning

confidence: 97%

“…The present numerical method has been validated for the time-averaged pressure distribution on a cascade blade with several angles of attack under non-cavitation conditions [1] . Mesh convergence has been examined [5] for a single hydrofoil under noncavitation and cavitation conditions in calculations with and without a turbulence model, i.e., the RANS model (Baldwin-Lomax model with Degani-Schiff modification). In addition, the unsteady characteristics of sheet cavitation in a single hydrofoil have been validated [5] through calculations with and without the RANS model.…”

Section: Numerical Schemementioning

confidence: 99%

“…Mesh convergence has been examined [5] for a single hydrofoil under noncavitation and cavitation conditions in calculations with and without a turbulence model, i.e., the RANS model (Baldwin-Lomax model with Degani-Schiff modification). In addition, the unsteady characteristics of sheet cavitation in a single hydrofoil have been validated [5] through calculations with and without the RANS model. The RANS calculation has been shown to be applicable to a non-cavitating flow field, while not contributing to unsteady cavitation, which is the objective of the present study.…”

Section: Numerical Schemementioning

confidence: 99%

“…7, which indicates that the PVR does not change in each acceleration field. According to a propagation mechanism proposed by the authors [5] , the PVR depends on the rotating stall speed, which is primarily affected by the fluid inertia force inside a cascade. In the present study, acceleration is applied in the axial direction, and the circumferential inertia force is not affected by the acceleration.…”

Section: Oscillating Characteristics Of Cavitation Instabilitiesmentioning

confidence: 99%

“…In addition, the possibility of the suppression of cavitation instabilities by a jet flow through a slit on cascade blades was reported [3] . Furthermore, we have classified three types of cavitation surges in cascade and the frequency characteristics of the cavitation surges [4] and have suggested a mechanism for the propagation direction of rotating cavitations in cascade [5] . The numerical method developed previously by present authors has been confirmed to be applicable to numerical simulation of cavitation instabilities.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis of the Influence of Acceleration on Cavitation Instabilities that arise in Cascade

Iga

Konno

2012

International Journal of Fluid Machinery and Systems

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In the turbopump inducer of a liquid propellant rocket engine, cavitation is affected by acceleration that occurs during an actual launch sequence. Since cavitation instabilities such as rotating cavitations and cavitation surges are suppressed during launch, it is difficult to obtain data on the influence of acceleration on cavitation instabilities. Therefore, as a fundamental investigation, in the present study, a three-blade cyclic cascade is simulated numerically in order to investigate the influence of acceleration on time-averaged and unsteady characteristics of cavitation that arise in cascade. Several cases of acceleration in the axial direction of the cascade, including accelerations in the upstream and downstream directions, are considered. The numerical results reveal that cavity volume is suppressed in low cavitation number condition and cavitation performance increases as a result of high acceleration in the axial-downstream direction, also, the inverse tendency is observed in the axial-upstream acceleration. Then, the regions in which the individual cavitation instabilities occur shift slightly to a low-cavitation-number region as the acceleration increases downstream. In addition, in a downstream acceleration field, neither sub-synchronous rotating cavitation nor rotating-stall cavitation are observed. On the other hand, rotating-stall cavitation occurs in a relatively higher-cavitationnumber region in an upstream acceleration field. Then, acceleration downstream is robust against cavitation instabilities, whereas cavitation instabilities easily occur in the case of acceleration upstream. Additionally, comparison with the Froude number under the actual launch conditions of a Japanese liquid propellant rocket reveals that the cavitation performance will not be affected by the acceleration under the current launch conditions.

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Section: Cavitation Instabilitiesmentioning

confidence: 97%