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Journal ArticleDOI

Numerical investigation on the hydrodynamic performance of high-speed planing hull with transom interceptor

16 Mar 2020-Ships and Offshore Structures (Informa UK Limited)-Vol. 15

Abstract: The study presents numerical investigations on hydrodynamic quality of high-speed planing hull with spray rails and interceptor. Interceptors are blades which extend vertically downwards at the bot...
Topics: Transom (58%), Hull (55%)
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Journal ArticleDOI
01 Nov 2021
Abstract: Different innovative ideas on simple stern fixtures such as stern wedges, flaps, interceptors have evolved over the past few years to improve the hydrodynamic performance of high-speed vessels, including planing crafts. This paper examines the hydrodynamic performance of a planing craft fitted with an interceptor alone and also an interceptor-flap combination at its stern, and the results are compared with the case where the craft uses the interceptor alone. An interceptor-flap combination is the one where an interceptor extends vertically downward at the transom with a flap attached to its end. Different angular orientations of the flap attached to interceptor bottom end and project towards aft are considered in the present study. The effectiveness of the integrated interceptor-flap system on the hydrodynamic performance of the vessel is influenced by the angular orientation of flap to the interceptor. Experiments were carried out on a planing hull with and without interceptor in the towing tank, Department of Ocean Engineering, Indian Institute of Technology Madras. Computational fluid dynamics (CFD) simulations are performed for the planing hull fitted with an integrated interceptor and flap. The investigations look into the aspects of vessel resistance, trim and bottom pressure distribution while it operates in calm water condition and at different speeds. The results show that trim and resistance of the vessel reduce with the use of integrated interceptor-flap at the stern with the flap angle at about 4° to the horizontal and they are less compared with a case where the only interceptor is used.

1 citations

Journal ArticleDOI
Chengliang Sun1, Xiaojun Xu1, Tengan Zou1Institutions (1)
03 Jun 2021
TL;DR: A high-performance, low-cost, and easy-to-operate mock-up of an amphibious vehicle designed to overcome the challenges faced in implementing and maintaining a non-streamlined design.
Abstract: Speed on water is a key indicator of amphibious vehicles. However, due to the inherent non-streamlined configuration, when reaching a certain velocity, the resistance acting on the vehicle hull is ...

1 citations

Cites background from "Numerical investigation on the hydr..."

  • ...Suneela et al.(18) analyzed the hydrodynamic performance of high-speed planing hull with interceptor at different heights using dynamic mesh....


  • ...Suneela et al.18 analyzed the hydrodynamic performance of high-speed planing hull with interceptor at different heights using dynamic mesh....


Journal ArticleDOI
Linhe Zheng1, Zhilin Liu1, Songbai Yang1, Shouzheng Yuan1  +2 moreInstitutions (1)
TL;DR: Simulation and experimental results verify that the installation position of appendages is reasonable and effective for improving the trimaran stability performance.
Abstract: To improve the stability performance of the trimaran, appendages were usually installed. Installing a larger-area appendage will increase the ship's resistance, and a smaller-area appendage has a limited stabilizing effect. Therefore, the design of appendages was a problem to be solved. Meanwhile, the installation position of the designed appendages was also worth studying. This study designed the appendages and investigated the installation position of stability appendages for a trimaran using computational fluid dynamics (CFD) simulation. The results of model tests and CFD simulations were compared, which verify the accuracy and feasibility of CFD simulation. T-foil and flap were selected as the trimaran vertical stability appendages. According to the appendage design basis and constraints, the shape and dimension are given through the design process. The flap was installed on the stern of the trimaran. Six longitudinal and four vertical installation positions were selected while the best installation position for the T-foil was obtained. Finally, simulation and experimental results verify that the installation position of appendages is reasonable and effective for improving the trimaran stability performance.

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Journal ArticleDOI
Abstract: The problem of surface ships free to pitch and heave in regular head waves is analyzed numerically with an unsteady Reynolds averaged Navier Stokes (URANS) approach. The unsteady single-phase level set method previously developed by the authors was extended to include six degrees of freedom (6DOF) motions. The method uses rigid overset grids that move with relative motion during the computation, and the interpolation coefficients between the grids are recomputed dynamically every time the grids move. The motions in each time step are integrated implicitly using a predictor–corrector approach. An earth-based reference system is used for the solution of the fluid flow, while a ship-based reference system is used to compute the rigid-body equations of motion. Predicted results for sinkage and trim and resistance at two Froude numbers (medium, Fr = 0.28 and large, Fr = 0.41) were compared against experimental data, showing good agreement. Pitch and heave motions were computed for near-resonant cases at Fr = 0.28 and 0.41, with regular linear head waves with slope ak = 0.025 and wavelength λ = 1.5 L , with L the ship length. The predicted motions compare favorably with existing experimental data. A solution for a large amplitude head wave case ( ak = 0.075) was also obtained, in which the transom wave breaks and extreme motions are observed. The medium Froude number case was subject to a verification and validation analysis. A problem with two ships pitching and heaving one behind the other is demonstrated.

235 citations

Journal ArticleDOI
Abstract: In the context of marine application of computational fluid dynamic (CFD), it is well known that the numerical simulations of planing craft are significantly less reliable than that of displacement ships. For this reason, it is important to perform a comprehensive approach to the verification and validation (V&V) methodology and procedures for simulating CFD planing craft. In the first part of this paper, an assessment of the accuracy and effectiveness of different simulation setups and techniques for planing craft is performed. In the second part, the results of the V&V study are reported for three different hull models at four Froude numbers (Fr). The Unsteady Reynolds-Averaged Navier-Stokes code results were validated using benchmark experimental data obtained for three hull models characterized by systematic variation of the length to beam ratio. Grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) were conducted using the main error and uncertainty estimation methods available in the literature. The same procedures were followed for the profiles of the wave patterns. The results showed that there was improved reliability of the numerical simulation of the planing craft in terms of the errors and uncertainties, related to the predictions of resistance, running attitude, and wave pattern. The results of the V&V study highlighted the fact that modeling of the planing craft is a critical point to improve the reliability of the numerical simulation.

49 citations

Journal ArticleDOI
Abstract: We present the results of simulations obtained with a free-surface flow solver based on the following method. The free surface is simulated by the “volume-of-fluid” interface capturing method. This code solves the Navier–Stokes equations using a finite-volume method adapted to a structured or unstructured mesh. The system is constructed using a fully coupled approach. This global approach allows the simulation of complex flow as a breaking or merging wave. Moreover, with the use of a 2D+T decomposition, it is possible to simulate three-dimensional steady flow.

32 citations

Journal ArticleDOI
Alexander Day, Christopher Cooper1Institutions (1)
Abstract: Interceptors have been widely used in recent years in fast ferries and small high-speed leisure and commercial craft for ride and trim control, and steering. In the context of high-performance sailing yachts, they first appeared in 2008 on the yacht Ecover 3 which was dismasted while leading the Vendee Globe Challenge race. However, in spite of their popularity in power craft, few studies have been published investigating the impact of interceptors on vessel performance, and apparently none in the case of sailing yachts. In the current study, interceptors are compared with an aerodynamic device known as a Gurney flap. It is shown that interceptors are generally substantially smaller than Gurney flaps. A comprehensive experiment programme is presented exploring the impact of interceptors on the performance of an Open 60 yacht hull. Results show a marked reduction in calm-water resistance over a wide speed range, with benefits of 10–18% in the speed range between 8 and 20 knots, accompanied by reduced sinkage and trim. The gains observed are much larger than those observed in powercraft, and also substantially greater than those achievable through trim changes by moving ballast longitudinally. The benefits appear to be largely sustained in small waves.

31 citations

Journal ArticleDOI
Abstract: A well-known instability of the high-speed planing crafts is the porpoising instability. This instability involves periodic, coupled heave/pitch oscillations possibly experienced in a planing vessel at high speeds. The porpoising can be controlled by using external devices. Interceptors are vertical blades installed symmetrically at the aft of the craft and have been introduced as a trim control appendage. Here, based on numerical methods and Savitsky porpoising theory, the effects of hydrodynamic interceptors on the porpoising control are investigated. Using computational fluid dynamics, the pressure distribution created by interceptor and its effects on porpoising are computed and then discussed. To model the flow around the vessel model, the Reynolds Average Navier Stokes (RANS) equations are applied. The work deals with craft with and without an interceptor at different heights. A dynamic grid mode involving two degrees of freedom is used. The results show that the interceptor causes an intense pressure at the stern bottom. It also decreases the trim and resistance of the vessel and increases the lift force coefficient which directly affects the porpoising instabilities. Based on the results, the interceptor can completely control the porpoising phenomenon.

24 citations

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