Ship twin-propeller jet model used to predict the initial velocity and velocity distribution within diffusing jet

Jinxin Jang, Wei-Haur Lam, Yonggang Cui, Tainming Zhang, Chong Sun, Jianhua Guo, Yanbo Ma, Shuguang Wang, Gerard Hamill

Research output: Contribution to journalArticle

5 Citations (Scopus)
34 Downloads (Pure)


The current research proposed the theoretical model for ship twin-propeller jet based on the axial momentum theory and Gaussian normal distribution. The twin-propeller jet model is compared to the more matured single propeller jet model with good agreement. Computational Fluid Dynamics (CFD) method is used to acquire the velocity distribution within the twin-propeller jet for understanding of flow characteristics and validation purposes. Efflux velocity is the maximum velocity within the entire jet with strong influences by the geometrical profiles of the blades. Twin-propeller jet model showed four-peaked profile at the initial plane downstream to the propeller compared to the two-peaked profile from a single-propeller. The four-peaked profile merges to be two-peaked velocity profile and then one-peaked profile due to the fluid mixing. Entrainment occurs between the ambient still water outside and the rotating flow within jet due to the high velocity gradient. The research proposes a twin-propeller jet theory with a serial of equations enabling the predictions of velocity magnitude within the jet.
Original languageEnglish
Number of pages14
JournalKSCE Journal of Civil Engineering
Issue number3
Early online date02 Jan 2019
Publication statusPublished - 02 Mar 2019


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