Experimental Investigation on Supercavitating Flow over Parabolic Cavitators

Abstract

In this paper experimental study was carried out to investigate supercavitation around parabolic cavitators. Various types of cavitators, such as disk, cone, and parabolic, were designed and manufactured. Also, the shape of the cavities formed behind these bodies were considered and compared. Dimensionless parameters such as dimensionless length and the diameter of the cavity as well as the dimensionless required air flow on the cavitators were obtained. The results showed that parabolic cavitators have an optimum design in comparison with the disk and cone cavitators due to their insignificant capability to reduce the drag force, yet the cavity's length has a moderate size. It was also observed that this type of cavitator is capable of forming a cavity with a dimensionless length up to L/d= 33 and a dimensionless width up to D/d= 3.6. Moreover, parabolic cavitators require the highest amount of air injected in comparison with the cone and disk types; therefore, they operate in lower cavitation numbers. Since no other experimental data has been reported so far, this work reports the experimental characteristic behavior of parabolic cavitators.

Numerical Analysis for Supercavitation Characteristics around Underwater Vehicle according to Ventilated Gas Temperature

“…Kim 등 [14] 은 3차원 나비에-스톡스(Navier-Stokes) 방정식에 기반한 자체 전산 해석 프로그램을 활용하여 수중운동체 주위 부분 공동 유동 해석을 수행했고, Ha 등 [15] 은 완전 압축성 효과를 고려한 수중운동체 주위 자연-분사 공동에 대한 다상 유동 전산 해석을 수행했 다. Hoang 등 [16] 은 자유 유동 온도에 따른 수중운동체 주위 공동 유동 해석을 수행했다. Salari 등 [17] , Moghimi 등 [18] , Javadpour 등 [19] 은 수중 터널에서 30도, 45도, 60…”

Insights into ventilation hysteresis shift due to flow unsteadiness in ventilated supercavitation

“…Their research has been conducted for a backward-facing model (BFM) with only a disk type cavitator. However, there is an inherent limitation with this type of cavitator configuration -it neglects the effects of the cavitator shape or the presence of the mounting strut, both of which have been shown to noticeably affect the cavity behaviors [7][8][9], especially the supercavity formation process [10]. Recently, Shao et al [11] studied the ventilation demands for a forward-facing model (FFM) with a variety of cavitator geometries (cone, disk, and nonaxisymmetric) to consider both the cavitator shape and the mounting strut effects.…”

Effect of mounting strut and cavitator shape on the ventilation demand for ventilated supercavitation

“…Specifically, they showed that cone and wedge cavitators result in a shorter and slimmer cavity compared to that generated by a disk cavitator with the same frontal area from [11]. Recently, Moghimi et al [12] conducted experiments using disk, cone and parabolic cavitators, and compared the corresponding cavity dimension, cavitation number and the overall drag reduction effect, which shows the parabolic cavitator leads to minimal drag among the three cavitators of the same frontal area. Although the abovementioned investigations have provided important guidance for cavitator design, there is still a dearth in the study of the effects of cavitator shapes on 𝐶 Qf and 𝐶 Qc .…”