Control volume determination for submerged waterjet system in self-propulsion. (1st December 2022)

• Record Type: Journal Article
• Authors: Jiang, Jiabing; Ding, Jiangming; Lyu, Ning; Luo, Hai; Li, Lingxun
• Is Part Of: Ocean engineering. Volume 265(2022)
• Publication Date: 2022-12-01
• Subjects: Submerged waterjet -- Self-propulsion -- Numerical simulation -- Control volume -- Streamtube -- Gross thrust; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2022.112594
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: The submerged waterjet is a novel propulsor designed for surface ships which is highly integrated with the aft-hull bottom. As the difficulty in measuring net thrust directly, the momentum flux method is suggested as the analysis procedure for ships propelled by submerged waterjets. This paper numerically investigates a high-speed displacement ship propelled by two submerged waterjets at 0.12 < Fr < 0.41 in model-scale. The control volume of the submerged waterjet system is firstly defined according to its working-principles. For the typical case here, the capture area of suction streamtube is appropriate to be located around 2.0–4.0 duct inlet diameter away from the duct inlet, while the capture area of jet streamtube is recommended to be 0.50 duct outlet diameter away from the duct outlet. The suction streamtube shows obvious contraction along inlet-direction, while the jet streamtube is much closer to an equal-diameter tube along jet-direction and its area keeps almost constant with Froude number. At 0.20 < Fr < 0.41, the jet system thrust deduction fraction hangs around a small negative-value for an appropriate control volume, showing small difference between gross thrust and net thrust of the submerged waterjet system in this paper. Highlights: The control volume of submerged-waterjet system in self-propulsion is specifically defined and determined. The appropriate determination on control volume leads to a smaller difference between gross thrust and net thrust of submerged waterjet at major speeds.