China
Africa
Explore chapters and articles related to this topic
Improvement of ships seakeeping performance by application of the full-scale CFD simulations
Published in Petar Georgiev, C. Guedes Soares, Sustainable Development and Innovations in Marine Technologies, 2019
For the purpose of the research the case study ship was selected - Navigator XXI (IMO 9161247). She is a training and research vessel originally designed to have high seaworthiness. The ship has V-shaped bulbous bow with a flare, full midship section and wide transom stern. The ship length is LOA=60.3 m and the Gross Tonnage is GT=1245. The vessel with a hull form ‘as built’ was noted as CSV1 (Case Study Vessel 1). Hull forms noted as CSV2, CSV3, CSV4 are re-designed variants of the case study vessel. The purpose of the hull shape modifications was to increase seakeeping performance. It was implemented by the application of innovative hull form concepts developed originally by leading design offices. Ship variant noted as CSV2 had modified bow section with unchanged midship section and stern in order to assess the influence of the X-bow concept. She was designed by taking a pattern of the X-bow with the use of data provided by the patent (WO 2006/096066 A1, 2006). Ship variant noted as CSV3 had the same bow and midship section as CSV2. However, the stern was re-designed to adopt the X-aft concept and resembles the cruiser stern. It allows to assess its influence on the ship performance. The variant of ship noted as CSV4 was completely different. The form of B-shaped bow was originally developed by the Havyard company. The variant CSV4 was similar to this concept and was adopted to preserve the main particulars of the case study vessel. All the analyzed hull forms are presented in Figure 1.
A numerical trim methodology study for the Kriso container ship with bulbous bow form variation
Published in Pentti Kujala, Liangliang Lu, Marine Design XIII, 2018
M. Maasch, E. Shivachev, A.H. Day, O. Turan
One of the methods to improve the hydrodynamic performance of ships when sailing at a speed different to the design speed or in adverse loading conditions is to operate the ship at a trim angle. This allows bringing certain ship hull geometry features, such as the bulbous bow, the stern bulb or the transom back into the design position (in reference to the design conditions). The potential of further improving the energy efficiency of ships when operating in trimmed conditions could be investigated by optimising those hull parts.
Comparison between empirical and CFD based methods for ship resistance and power prediction
Published in C. Guedes Soares, T.A. Santos, Trends in Maritime Technology and Engineering Volume 1, 2022
H. Islam, M. Ventura, C. Guedes Soares, M. Tadros, H.S. Abdelwahab
DTC is a container ship model with a bulbous bow, a large bow flare, and a transom stern with a large overhang (El-Moctar et al., 2012). It is a single-screw vessel with a propeller and a rudder. The ship is also equipped with a bilge keel, comprised of five segments per ship side. However, for simulation, only the bare hull was considered. The main particulars of the ship are mentioned in Table 2 and the ship’s body plan is shown in Figure 2.
Time domain potential and source methods and their application to twin-hull high-speed crafts
Published in Ships and Offshore Structures, 2023
As the DUT twin-hull has a transom stern, there would be flow separation due to immersion of the transom stern at a high Froude number Fn = 0.75. The flow separation influences the viscous effects which would affect the response amplitude at the resonance frequency region as can be observed in Figures 18 and 19. However, the viscous damping is usually limited for slender vessels advancing at high speed in head sea waves while an important damping effect is the hull-lift damping for which dry transom stern is important (Faltinsen 2005). Owing to the increase in viscosity and hull-lift damping, the damping of the floating system would increase which result in the reduction of the motion amplitude. It is expected that the potential theory based numerical methods overpredict the motion amplitudes as the potential theory ignore the viscous effects and hull-lift damping. As the ITU-WAVE numerical code depends on the three-dimensional potential formulation for arbitrary multi-hull bodies, the overprediction of wave amplitudes can be observed clearly for heave and pitch modes in Figures 18 and 19 at resonance region, while the phase angles for both heave and pitch modes are in better agreement with the experimental results. The ITU-WAVE numerical results also show a small shift against the experimental results in motion amplitudes towards higher frequencies in the pitch mode as in Figure 19.
A study on the added resistance of a catamaran advancing in waves considering variations of both operating and geometric parameters
Published in Ships and Offshore Structures, 2021
Giuliano Vernengo, Diego Villa, Dario Bruzzone, Luca Bonfiglio
Considering the experimental running attitude of the catamaran in calm water shown in Figure 18 in terms of both sinkage and trim angle (Van't Veer 1998a), a maximum variation of the trim angle equal to about , bow up, has been observed. In the framework of a systematic analysis, even tough such a trim angle occurs in the range it has also been considered at Fn = 0.4 in order to highlight a trend of the response. The frequency domain BEM computations have been carried out considering the hull initially inclined at two trim angles, and , respectively as shown in Figure 19. Obviously as the bow rises due to the trim angle, the higher stern draught slightly increases the transom area. This geometric parameter has been included into this systematic study since it can be controlled by using ad-hoc devices such as e.g. trim tabs. Considering a balance between the possible positive effect of an imposed trim variation and the additional resistance induced by any of these devices, an optimal configurations might be found. To find such a configuration is out of the scope of the proposed analysis which focuses on the first step, i.e. trying to understand the trends of the response due to parameters changes.
Experimental and numerical study on the scale effect of stern flap on ship resistance and flow field
Published in Ships and Offshore Structures, 2020
Ke-wei Song, Chun-yu Guo, Chao Wang, Cong Sun, Ping Li, Ruo-fan Zhong
The research object of this study is the vessel DTMB5415, which has a transom stern and a bulbous bow. Based on this model ship, a large number of experiments (Olivieri et al. 2001; Bhushan et al. 2019) and numerical studies (Toxopeus et al. 2018) have been conducted, which can provide reference and validation data for the numerical simulation conducted in this study. The length of the full-scale ship is 142 m, the model ship length is 5.72 m, and the scale ratio is 24.824. Both the US Navy report (Cusanelli and Hundley 1999) and the test results of Maki et al. (2016) show that the optimum angle of stern flap is approximately 10° for the DTMB5415 ship. Based on this, 8°, 10°, and 12° stern flaps (designated as Flaps 1, 2, and 3, respectively) were selected to obtain a more suitable angle to analyse the scale effect of the stern flap. The experimental photos of the DTMB5415 and stern flap (Flap 2) are shown in Figure 1, and the specific parameters are listed in Table 1.