Ship Twin-propeller Jet Model used to Predict the Initial Velocity and Velocity Distribution within Diffusing Jet

Jiang, Jinxin; Lam, Wei-Haur; Cui, Yonggang; Zhang, Tianming; Sun, Chong; Guo, Jianhua; Ma, Yanbo; Wang, Shuguang; Hamill, Gerard

doi:10.1007/s12205-019-1370-x

Cited by 13 publications

(16 citation statements)

References 11 publications

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“…Jiang et al [15] proposed the flow structure of the twin-propeller jet has two zones as a single propeller, as shown in Figure 1. The zone of flow establishment can be divided to be non-interference zone (ZFE-TP-NI) and inference zone (ZFE-TP-I).…”

Section: Propeller Jetmentioning

confidence: 99%

“…Hamill et al [11] include the effects of the quay wall in the seabed scour prediction. The aforementioned researchers emphasised on the estimation of maximum scour depth induced by ship propeller wash. Wang et al [12], Sun et al [13] and Ma et al [14] implemented the foundation of propeller jet induced scour to predict the wake of tidal turbine and the tidal turbine induced scour and Jiang et al [15] proposed the theoretical structure of ship twin propeller jet.…”

Section: Introductionmentioning

confidence: 99%

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Scour Induced by Single and Twin Propeller Jets

Cui

Lam

Zhang

et al. 2019

Water

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Single and twin ship propeller jets produce scour holes with deposition dune. The scour hole has a maximum depth at a particular length downstream within the propeller jet. Existing equations are available to predict maximum scour depth and the corresponding scour length downstream. Experiments conducted with various physical propeller models, rotational speeds, propeller-to-propeller distances and bed clearances are presented. The measurements allowed a better understanding of the mechanism of temporal scour and deposition formation for scour caused by single-propeller and twin-propeller. Results show that the propeller jet scour profiles can be divided into three zones, which are the small scour hole, primary scour hole and deposition dune. An empirical 2D scour model is proposed to predict the scour profile for both a single-propeller and twin-propeller using a Gaussian normal distribution.

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Section: Propeller Jetmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Scour Induced by Single and Twin Propeller Jets

Cui

Lam

Zhang

et al. 2019

Water

Self Cite

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“…The mass flow rate that does not pass through the tidal current turbine (Equation (10)) can be represented by inserting U 2/3 of Equation (13), as shown in Equation (14).…”

Section: Tip-bed Velocity Equationmentioning

confidence: 99%

“…Albertson et al [11], Hamill [12], and Lam et al [13] investigated velocity distribution within propeller wake and proposed wake distribution equations. Jiang et al [14] proposed a theoretical model for a ship twin-propeller jet. The scour pattern induced by a propeller was attributed mainly due to the expansion of a propeller wake.…”

Section: Introductionmentioning

confidence: 99%

Tip-Bed Velocity and Scour Depth of Horizontal-Axis Tidal Turbine with Consideration of Tip Clearance

et al. 2019

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The scouring by a tidal turbine is investigated by using a joint theoretical and experimental approach in this work. The existence of a turbine obstructs a tidal flow to divert the flow passing through the narrow channel in between the blades and seabed. Flow suppression is the main cause behind inducing tidal turbine scouring, and its accelerated velocity is being termed as tip-bed velocity (Vtb). A theoretical equation is currently proposed to predict the tip-bed velocity based on the axial momentum theory and the conservation of mass. The proposed tip-bed velocity equation is a function of four variables of rotor radius (r), tip-bed clearance (C), efflux velocity (V0) and free flow velocity (V∞), and a constant of mass flow coefficient (Cm) of 0.25. An experimental apparatus was built to conduct the scour experiments. The results provide a better understanding of the scour mechanism of the horizontal axis tidal turbine-induced scour. The experimental results show that the scour depth is inversely proportional to tip-bed clearance. Turbine coefficient (Kt) is proposed based on the relationship between the tip-bed velocity and the experimental tidal turbine scour depth. Inclusion of turbine coefficient (Kt) into the existing pier scour equations can predict the maximum scour depth of a tidal turbine with an error range of 5–24%.

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“…Hamill [5] measured the flow field within the jet form a single-propeller while using Pitot tubes, while Lam [6] proposed a semi-empirical model that would predict the velocity field within the jet using axial momentum theory with Laser Doppler Anemometry (LDA) and Computational Fluid Dynamics (CFD) corrections. Jiang et al [7] improved the single-propeller jet model to be a semi-empirical model for twin-propeller…”

Section: Introductionmentioning

confidence: 99%

Temporal Model for Ship Twin-Propeller Jet Induced Sandbed Scour

Cui

Lam

Zhang

et al. 2019

JMSE

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This research paper proposes the use of empirical equations to estimate the temporal maximum scour that is induced by twin-propeller ( ε t w i n = Ω t [ l n ( t ) ] Γ t ) when acting over non-cohesive bed materials. A purpose built experimental apparatus is used to obtain the measurement data required for the calculation of the empirical constants. The output from rigorous experimental investigations demonstrates that the maximum scour depth produced from the operation of twin-propeller ( ε t w i n ), within the confines of a harbour basin, varies as a logarithmic function of time. A dimensional analysis of the standard single propeller configuration is used as the foundation upon which the scour equation is postulated. This is extended to include the influence of the operating distance between the twin-propeller configurations for the first time. The division of scours by twin-propeller and single-propeller ( ε twin / ε m ) enables the establishment of mathematical relation to calculate C1, C2, A, and B. The constants are C 1 = 366.11, C 2 = 0.3376, A = 0.859, and B = 0.1571. The proposed scour equation is more reliable within the time zone up to two hours based on the experimental data.

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Ship Twin-propeller Jet Model used to Predict the Initial Velocity and Velocity Distribution within Diffusing Jet

Cited by 13 publications

References 11 publications

Scour Induced by Single and Twin Propeller Jets

Scour Induced by Single and Twin Propeller Jets

Tip-Bed Velocity and Scour Depth of Horizontal-Axis Tidal Turbine with Consideration of Tip Clearance

Temporal Model for Ship Twin-Propeller Jet Induced Sandbed Scour

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