Hull Form Optimization for a 62000DWT Heavy Lift Multi-Purpose Vessel

2021 ◽  
Author(s):  
Shuhui Jiang ◽  
Li Zhang ◽  
Weimin Chen
Keyword(s):  
Optimization Method ◽  
Total Resistance ◽  
Hull Form ◽  
Wake Field ◽  
Resistance Reduction ◽  
Heavy Lift ◽  
Design Speed ◽  
Pressure Resistance ◽  
Profile Optimization ◽  
Viscous Pressure

Abstract A new optimized hull form was proceeded based on a parent ship 60000 DWT bulk carrier. The goal of optimization is to obtain better resistance performance in the loading conditions of scantling draught and design draught. Firstly, the numerical simulation of the parent ship was carried out, the flow field information around the hull was analyzed, the area of high or low pressure was checked, and the area was optimized to make the pressure distribution more uniform. At the same time, the bow entrance section was optimized to reduce the wave-making resistance, and the length of the run body was lengthened to reduce the flow separation area and the viscous pressure resistance. Aiming at these above optimization objectives, the deformation range of hull form was set by commercial software CAESES, and the total resistance of generated optimized cases was solved by SHIPFLOW and evaluated by STARCCM+ software. To grantee the resistance reduction at both design draught and scantling draught, by using the operation profile optimization method, the resistance weights of scantling draught and design draught were set as 50% respectively, that is, the total resistance of optimized hull form equals 50% resistance of design draught condition and 50% resistance of scantling draught condition. The optimization results of total resistance were compared and analyzed, and the cases with relatively minimum total resistance were obtained. On this basis, the wake field at the propeller disk was optimized either, and finally, the target optimization of hull form was obtained. The numerical results showed that, compared with the parent ship, the total resistance at the design speed of the design draught was reduced by about 1.64%, about 2.10% at the design speed of the scantling draught. The wake distribution on the propeller area was more uniform. The final optimized hull form meets the target requirements.

Optimization of the Hybrid Ship Transport Factor through Retrofitted Wave Cancelling Side-Hull Expansions and Bow Bulb

2015 ◽  
Author(s):  
Manivannan Kandasamy ◽  
Ping C. Wu ◽  
Scott Bartlett ◽  
Loc Nguyen ◽  
Frederick Stern
Keyword(s):  
High Performance ◽  
Negative Impact ◽  
Fiscal Year ◽  
Hull Form ◽  
Transport Factor ◽  
Resistance Reduction ◽  
The Us ◽  
Us Navy ◽  
Speed Range ◽  
Design Speed

The US Navy is currently considering the introduction of a Flight III variant beginning with DDG-123 in Fiscal Year 2016. The new design incorporates a new combat system and associated power and cooling upgrades. The overall system improvements increase the payload of the ship and the resulting increased displacement has a negative impact on the service life allowance for range, fuel consumption and sea-keeping characteristics. The present objective is to increase the hull displacement without resistance and sea-keeping penalty and with minimal modifications to the baseline DTMB-5415 design (open literature surrogate of the existing DDG-51 hull form) by using retrofitted blisters in the form of side hull expansions and a bow-bulb. The investigation makes use of high-performance CFD computing for analysis of wave cancellation mechanisms. A candidate modified 5415 design with both blisters and bow bulb shows a resistance reduction of ~11% w.r.t.the baseline 5415 in the design speed range of 15-19 knots, even though the displacement is increased by 8%, such that the transport factor is increased by 19%.

Stern Flap–Waterjet–Hull Interactions and Mechanism: A Case of Waterjet-Propelled Trimaran With Stern Flap

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Lei Zhang ◽  
Jianing Zhang ◽  
Yuchen Shang
Keyword(s):  
High Efficiency ◽  
Navier Stokes ◽  
Local Effects ◽  
Resistance Components ◽  
Leading Role ◽  
Resistance Reduction ◽  
Sinkage And Trim ◽  
Improved Performance ◽  
Design Speed ◽  
Pressure Resistance

Abstract To research the stern flap (SF) and waterjet–hull interaction, unsteady Reynolds-averaged Navier–Stokes (URANS) simulations for a waterjet-propelled trimaran considering sinkage and trim are performed. Uncertainty analysis of the numerical results for the bare hull (BH) model is presented. At the design speed Froude number (Fr) of 0.6 and under displacement state, the model-scaled trimaran, installed with stern flaps of varied angle and length, tests the BH and self-propulsion (SP) performance based on URANS simulations. For the resistance, the global effects due to motions and the local effects of SF, waterjets (WJ), and the coupled term between SF and WJ on the hull are separately analyzed. Taking the waterjet propulsion system into account, an SP model with reasonable stern flap effectively reduces the trim, the resistance acting on the hull and the waterjet thrust deduction which contributes to energy-saving and high-efficiency propulsion. The mechanism of the improved performance of the waterjet-propelled trimaran with stern flaps is discussed. For the resistance increment, the global effects, the local effects of SF and WJ are the major reason for resistance increase, and the nonlinear coupled term of local effects contributes to the resistance reduction most. In addition, the different resistance components of frictional, hydrostatic, and hydrodynamic are separately researched, which shows that the pressure resistance components plays a leading role in the total resistance reduction in the SP model with the suitable SF.

scholarly journals Hull form optimization in the conceptual design stage considering operational efficiency in waves

2018 ◽  
Vol 233 (3) ◽  
pp. 745-759 ◽  
Author(s):  
Yoo-Won Jung ◽  
Yonghwan Kim
Keyword(s):  
Optimization Method ◽  
Operational Efficiency ◽  
Hydrodynamic Performance ◽  
Design Stage ◽  
Total Resistance ◽  
Added Resistance ◽  
Slender Body Theory ◽  
Hull Form ◽  
Weather Factor ◽  
Calm Water

This study focuses on the optimization of ship dimensions by considering hydrodynamic performance in waves. In actual seaways, a ship experiences speed loss due to environmental loads by waves and wind. Therefore, along with calm water resistance, speed loss in waves should be considered in the hull form design in order to improve operational efficiency in waves. However, a trade-off may be needed between total resistance on the ship and the speed loss in waves. To address this problem, Non-dominated Sorting Genetic Algorithm II, which is a multi-objective optimization method, is used to minimize the total resistance on a ship in seaways and the speed loss by additional resistance. In the optimization process, added resistance is predicted using a numerical method based on slender-body theory, Maruo’s far-field formulation, and an empirical formula for added resistance in short waves. The speed loss in waves, which can be expressed by a weather factor ( fw), is estimated using power–speed curves. This article introduces some examples of the sensitivity analysis of added resistance and speed loss in waves to the variations of ship dimensions. Finally, the optimization solutions on a Pareto front set are compared to a basis ship in terms of hull form, and the corresponding hydrodynamic performances are evaluated.

Bow and Stern Shape Integrated Optimization for a Full Ship by a Simulation-based Design Technique

2014 ◽  
Vol 58 (02) ◽  
pp. 83-96 ◽  
Author(s):  
Sheng-Zhong Li ◽  
Feng Zhao ◽  
Qi-Jun Ni
Keyword(s):  
Optimization Design ◽  
Fluid Dynamic ◽  
Optimization Algorithms ◽  
Navier Stokes ◽  
Total Resistance ◽  
Hull Form ◽  
Wake Field ◽  
Simulation Based Design ◽  
Simulation Based ◽  
Saving Effect

Advanced computational fluid dynamic (CFD) techniques and optimization algorithms are successfully integrated together into what is known as Simulation-based Design (SBD) techniques, which open a new situation for hull-form optimization design and configuration innovation. In this article, fundamental elements of the SBD techniques are described and crucial components are analyzed profoundly with a focus on breaking through key technologies as global optimization algorithms, hull geometry modification and reconstruction, and code integration. Then, combined with high-fidelity CFD codes (on Reynolds-averaged Navier-Stokes), an automatic hull-form design optimization framework is established. Based on that, the full ship (bulk carrier) is optimized by selecting the total resistance and the quality of propeller disk wake field as objective functions. The results show that the decrease of the total resistance is significant at the possible speed range with a reduction of approximately 5% taking into account gains of propulsion efficiency produced by the improvement of wake field, the comprehensive energy-saving effect will be further expanded. The example confirms the applicability of the developed SBD frame-work to the full ship design problems.

Optimization on Resistance Performance of High Speed Unmanned Surface Vehicle in Middle-Low Speed

2011 ◽  
Vol 311-313 ◽  
pp. 2389-2392
Author(s):  
Wei Jia Ma ◽  
Hua Wei Sun ◽  
Yong Jie Pang
Keyword(s):  
High Speed ◽  
Optimization Method ◽  
Resistance Coefficient ◽  
Total Resistance ◽  
Hull Form ◽  
Unmanned Surface Vehicle ◽  
Low Speed ◽  
Non Linear Programming ◽  
Hull Forms ◽  
Resistance Performance

Unmanned surface vehicle has been the concern of the researchers at home and abroad as a new kind of unmanned platform ,especially for the middle-low speed resistance performance .An optimization method is proposed in this paper to find a hull form with perfect resistance performance in middle-low speed .This paper combines wave resistance and non-linear programming , Moreover, some hull forms are optimized to meet the combination of optimization punishing function with practical requirements and objective function to obtain Optimization form. The paper compared wave-making resistance coefficient and Total resistance (Newton) of Unit displacement (ton) between patent form and Optimization form to Show the feasibility of this method .The optimization results can provide reference for the subsequent hull form.

Development and Assessment of a Total Resistance Optimized Bow for the AE 36

1994 ◽  
Vol 31 (02) ◽  
pp. 149-160
Author(s):  
Donald C. Wyatt ◽  
Peter A. Chang
Keyword(s):  
Experimental Data ◽  
Optimization Procedure ◽  
Wave Resistance ◽  
Scale Model ◽  
Optimization Approach ◽  
Nonlinear Constraints ◽  
Total Resistance ◽  
Hull Form ◽  
Final Design ◽  
Resistance Data

A numerically optimized bow design is developed to reduce the total resistance of a 23 000 ton ammunition ship (AE 36) at a speed of 22 knots. An optimization approach using slender-ship theory for the prediction of wave resistance is developed and applied. The new optimization procedure is an improvement over previous optimization methodologies in that it allows the use of nonlinear constraints which assure that the final design remains within practical limits from construction and operational perspectives. Analytic predictions indicate that the AE 36 optimized with this procedure will achieve a 40% reduction in wave resistance and a 33% reduction in total resistance at 22 knots relative to a Kracht elliptical bulb bow design. The optimization success is assessed by the analysis of 25th scale model resistance data collected at the David Taylor Research Center deepwater towing basin. The experimental data indicate that the optimized hull form yields a 51% reduction in wave resistance and a 12% reduction in total resistance for the vessel at 22 knots relative to the Kracht bulb bow design. Similarly encouraging results are also observed when comparisons are made with data collected on two other conventionally designed AE 36 designs.

Numerical study on the mechanism of drag reduction for interceptors on planning boats

2021 ◽  
Author(s):  
Lianzheng Cui ◽  
Zuogang Chen ◽  
Yukun Feng
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Dynamic Pressure ◽  
Motion Model ◽  
Gauge Pressure ◽  
Reduction Effect ◽  
Pressure Resistance ◽  
Viscous Pressure

The drag reduction effect of interceptors on planning boats has been widely proven, but the mechanism of the effect has been rarely studied in terms of drag components, especially for spray resistance. The resistance was caused by the high gauge pressure under the boats transformed from the dynamic pressure, and it is the largest drag component in the high-speed planning mode. In this study, numerical simulations of viscous flow fields around a planning boat with and without interceptors were conducted. A two degrees of freedom motion model was employed to simulate the trim and sinkage. The numerical results were validated against the experimental data. The flow details with and without the interceptor were visualized and compared to reveal the underlying physics. A thinner and longer waterline could be achieved by the interceptor, which made the boat push the water away more gradually, and hence, the wave-making resistance could be decreased. The improved waterline also reduced the component of the freestream normal to the hull surface and led to the less transformed dynamic pressure, resulting in the lowAer spray resistance. Furthermore, the suppression of the flow separation could also be benefited from the interceptor; the viscous pressure resistance was therefore decreased.

A Comparison of Several Strategies to Optimize a Ship’s Aft Body

2011 ◽  
Vol 27 (04) ◽  
pp. 202-211
Author(s):  
Auke van der Ploeg
Keyword(s):  
Viscous Flow ◽  
Scale Effects ◽  
Full Scale ◽  
Ship Hull ◽  
Hull Form ◽  
Wake Field ◽  
Hull Forms ◽  
Definition Of

This paper describes a procedure to optimize ship hull forms, based on double body viscous flow computations with PARNASSOS. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. One of the object functions is an estimate of the required power. In this paper we will focus on how to improve this estimate, by using the B-series of propellers. Results of systematic variations applied to the VIRTUE tanker together with scale effects in the computed trends will be discussed. In addition, we will demonstrate how the techniques discussed in this paper can be used to design a model that has a wake field that strongly resembles the wake of a given containership ship at full scale.

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