Multi-objective optimization of trimaran sidehull arrangement via surrogate-based approach for reducing resistance and improving the seakeeping performance

2020 ◽  
pp. 147509022098027
Author(s):  
Amin Nazemian ◽  
Parviz Ghadimi
Keyword(s):  
Drag Reduction ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Computational Time ◽  
Vertical Position ◽  
Vertical Acceleration ◽  
Seakeeping Performance ◽  
Hull Design ◽  
Hull Forms ◽  
Heave Motion

Trimaran hull forms have been very attractive in the past decade. Hydrodynamic performance of trimaran ships is influenced by sidehull arrangement. The present study was intended to construct a surrogate model for better understanding of the hydrodynamic performance of a trimaran ship. Accordingly, seakeeping and resistance of an inverted-bow trimaran were considered as objectives of a simulation-based design (SBD) optimization framework. Different longitudinal, transversal, and vertical position of trimaran’s sidehull were investigated based on an advanced free-surface steady Reynolds-averaged Navier–Stokes (URANS) solver within StarCCM+ for resistance calculation and 3D panel method in Ansys-AQWA for seakeeping analyses. Quality and applicability of metamodeling optimization and its computational time were examined for future trimaran hull design projects. Total resistance for drag reduction, pitch and heave motion, and vertical acceleration at fore perpendicular for seakeeping performance were objectives of the study. The optimization results indicated a 6.9% drag reduction and 4.7% improvement in seakeeping performance, which yield lower longitudinal and large transversal distances of the sidehull. Furthermore, the conducted investigations demonstrated the effectiveness and capability of the proposed optimization platform for other marine industrial projects.

Experimental Study on Hydrodynamics of Hybrid Deep-V Monohull With Different Built-Up Appendages

2018 ◽  
Author(s):  
Shuzheng Sun ◽  
Hui Li ◽  
Muk Chen Ong
Keyword(s):  
Model Test ◽  
Performance Model ◽  
Hydrodynamic Performance ◽  
Irregular Waves ◽  
Hydrodynamic Characteristics ◽  
Vertical Acceleration ◽  
Test Results ◽  
Regular Waves ◽  
Sea State ◽  
Seakeeping Performance

The hydrodynamic characteristics of a hybrid deep-V monohull with different built-up appendages are investigated experimentally in order to improve the resistance and seakeeping performance. Model tests have been carried out to study the hydrodynamic performance between a bare deep-V vessel and a deep-V monohull with different built-up appendage configurations (i.e. a hybrid deep-V monohull). From the model test results, it is found that the existence of the appendages will reduce the amplitude of pitching angle and bow vertical acceleration compared to that of the bare deep-V vessel in heading regular waves. However, the resistances for the hybrid deep-V monohull with built-up appendages are increased 15.6% for Fn = 0.264, and 0.1% for Fn = 0.441 compared to the resistance of the bare deep-V vessel. The model test results of seakeeping performance in irregular waves show that the hybrid deep-V monohull gives a better seakeeping performance than the deep-V vessel. The pitching angle and bow vertical acceleration of the hybrid deep-V monohull containing a built-up appendage are reduced 15.3% and 20.6% compared to the deep-V monohull in irregular waves at Fn = 0.441 in 6th class sea state (H1/3 = 6m).

Numerical Analysis of Propeller During Heave Motion Near a Free Surface

2017 ◽  
Vol 51 (1) ◽  
pp. 40-51 ◽  
Author(s):  
Wang Lian-zhou ◽  
Guo Chun-yu ◽  
Wan Lei ◽  
Su Yu-min
Keyword(s):  
Free Surface ◽  
Coupling Effect ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Grid Technology ◽  
Thrust Coefficient ◽  
Motion State ◽  
Sinusoidal Motion ◽  
Torque Coefficient ◽  
Heave Motion

AbstractThe interaction between the free surface and the propeller during heave motion near the free surface was analyzed numerically using the Reynolds-Averaged Navier-Stokes (RANS) method. The coupling effect between the rotation and heave motions of the propeller was modeled using a motion equation developed in this study; the heave motion was simplified as a periodic motion based on the sinusoidal motion law; and the transfer of numerical values for unsteady flow fields was implemented using overset grid technology. A comparative analysis of the unsteady thrust coefficient and torque coefficient under different advance coefficient conditions was conducted, and the air ingestion phenomenon of the propeller was analyzed. The research highlighted the interaction between the coupled heave and rotation motions of the propeller and the free surface. The results showed that, when the advance coefficient was low, the hydrodynamic performance of the propeller during heave motion near a free surface was strongly influenced by the free surface and that a remarkable interaction existed between the propeller and the free surface. As the advance coefficient increased, the interaction between the propeller and the free surface weakened. The air ingestion that the propeller exerts upon the free surface during heave motion is a complex coupled superposition process. This phenomenon is correlated to the motion state and working time of the propeller, as well as the distance between the propeller and the free surface.

Analysis of Variance to Determine the Effect of Hull Form Parameters on Resistance and Seakeeping Performance for PSV Hulls

2016 ◽  
Author(s):  
Nicholas Boyd ◽  
David Molyneux
Keyword(s):  
Analysis Of Variance ◽  
Statistical Design ◽  
Design Parameters ◽  
Statistical Design Of Experiments ◽  
Hull Form ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Hull Design ◽  
Hull Forms ◽  
The Relationship

Throughout the world many Platform Supply Vessel designs have been proposed as the optimal form for their given operating environment, but evaluating these claims has been difficult due to a poor understanding of the relationships between hull form shapes and performance for these vessels. This paper presents the results of analysis aimed at determining these relationships. Results of CFD calculations to determine the Effective Horsepower/tonne for a series of PSV designs were presented in the paper A step towards an optimum PSV Hull form. This paper presents results for 16 separate hull forms, which were designed as each possible combination of four two-level hull form parameters. The hull form features considered were bow shape (vertical stem or bulbous), flat of bottom (flat or deadrise), length of parallel mid body (short or long), and stern shape (convention or integrated); resistance was calculated at two typical operating speeds (10 and 14 knots). This set of results was favourable for analysis using the statistical design of experiments technique: analysis of variance, which was used to determine the relationship between the hull and resistance performance. The same hull form series was used to study the effects of the hull form parameters on motions in head waves. A 2 level factorial experiment was designed based on the hull parameters with the heave and pitch response calculated using the potential flow ship motion prediction code Shipmo3D, for each of two representative wave conditions (summer light seas and winter heavy seas) at the zero speed and 10 knot operating speed. Analysis of variance was used to analyze the heave and pitch responses measured, and was used to determine the relationship between each hull parameter and each response. In both cases a 5% F-test was used to determine the significance of each parameter studied, and the significant effects were analyzed to determine their contributions to the overall model of the data. The results have found the relationships between the hull design parameters and the Effective Horespower/tonne, heave, and pitch response of the vessel, indicating which factors provide the largest contribution to minimizing each response. The interaction effects between factors were also examined to allow for a generalized understanding of the resulting effect of selecting one hull parameter over another. A numerical model combining all significant factors was fitted to the data, allowing for multiple objective optimization to determine which hull forms provide the most desirable performance for each response.

On the Hydrodynamics of Tandem-Hull Marine Vehicles

1986 ◽  
Vol 30 (04) ◽  
pp. 275-286
Author(s):  
M. H. Patel
Keyword(s):  
Oil Production ◽  
Diffraction Theory ◽  
Model Tests ◽  
Hydrodynamic Performance ◽  
Scale Model ◽  
Hydrodynamic Behavior ◽  
Marine Vehicles ◽  
Hull Design ◽  
Heave Motion ◽  
Wave Induced

The development of ship-shape marine vehicles in naval architecture and semisubmersibles in offshore engineering has proceeded along separate lines with each type of vessel being used for quite different operational needs. A tandem-hull marine vehicle offers a design that bridges the gap in between with a hydrodynamic performance that includes the desirable characteristics of both ships and semisubmersibles for floating oil production applications. A tandem-hull vessel consists of a fully submerged hull positioned a small distance below a surface-piercing hull with interhull bracing connections between the two. However, there are a number of unifying considerations which suggest that all three types of vessels can be regarded as part of a wider family of hull shapes. This paper presents a survey of floating vessel designs to illustrate this point and to highlight the position of a tandem hull as being a design midway between ship and semisubmersible. Leading particulars of the surveyed vessels are manipulated into nondimensional ratios and plotted to show their relationship with each other. The paper also presents a simplified hydrodynamic analysis for heave motion of a tandem hull to highlight the main features underlying its hydrodynamic behavior. The tandem-hull design is also analyzed in detail by a more exact diffraction theory based analysis for wave-induced motions and interhull forces. These predicted motions and forces are compared with data from 1: 75 scale model tests. The analyses and model tests are used to illustrate the principal features that govern hydrodynamic behavior of tandem-hull marine vehicles and that lead to some of their operational advantages as floating oil production vessels.

Maneuvering and Seakeeping Performance of a Generic Tug Based on Numerical Simulations

2020 ◽  
Author(s):  
Yingying Zheng ◽  
Yuting Jin ◽  
Lucas J. Yiew ◽  
Allan R. Magee
Keyword(s):  
Numerical Simulations ◽  
Hydrodynamic Performance ◽  
Scale Model ◽  
Navier Stokes ◽  
Published Data ◽  
Real Time Control ◽  
Hydrodynamic Behavior ◽  
Digital Twin ◽  
Time Control ◽  
Seakeeping Performance

Abstract Autonomous tugs may play an important role in future ports, due to the shortage of qualified mariners. A digital twin (mathematical model incorporating a vessel’s hydrodynamic behavior and response, suitable for real-time control) would be needed for autonomous operations. Yet, partly because tugs are generally high-powered and very maneuverable compared to conventional vessels, there is little published data on the hydrodynamic performance of such vessels. As a first step in the development of the tug’s digital twin, the present work studies the maneuvering and seakeeping performance of a generic tug at model scale. Numerical simulations are performed for an approximately 1:10 scale model for standard resistance, static and dynamic captive and seakeeping cases. Reynolds-Averaged Navier-Stokes (RANS) k-ω model is employed for the simulations including the free surface through the Volume of Fluid approach. The hydrodynamic forces and moments on the tug model in the simulations of the standard resistance and the static and dynamic captive cases, as well as the tug model’s motions and the added resistance in headseas, are investigated. The simulation results provide data to build a mathematical maneuvering model for the tug based on 4-DoF MMG manoeuvring model, which serves as the digital twin in this case.

scholarly journals Numerical Prediction of the Vertical Responses of Planing Hulls in Regular Head Waves

2020 ◽  
Vol 8 (6) ◽  
pp. 455
Author(s):  
Emre Kahramanoğlu ◽  
Ferdi Çakıcı ◽  
Ali Doğrul
Keyword(s):  
Transfer Functions ◽  
Cost Effective ◽  
The Body ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Large Wave ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Long Time ◽  
Fluid Body

The evaluation of the hydrodynamic performance of planing vessels has always been one of the most attractive study fields in the maritime agenda. Resistance and self-propulsion studies have been performed using experimental and numerical methods by researchers for a long time. As opposed to this, the seakeeping performance of planing hulls is assessed with 2D approximation methods, but limitedly, while the experimental campaign is not cost-effective for several reasons. With this motivation, pitch and heave transfer functions and accelerations were obtained for a monohedral hull and a warped hull using a state of art commercial Reynolds-averaged Navier–Stokes (RANS) solver, in this study. Moreover, 2-DOF (degree of freedom) dynamic fluid–body interaction (DFBI) equations were solved in a coupled manner with an overset mesh algorithm, to find the instantaneous motion of the body. After verification, obtained numerical results at three different Froude numbers and a sufficiently large wave frequency range were compared with the experiments. The results showed that the employed RANS method offers a very accurate prediction of vertical motions and accelerations for planing hulls.

Aero-Thermal Characterization of Accelerating and Diffusing Passages Downstream of Rotating Detonation Combustors

2021 ◽  
Author(s):  
James Braun ◽  
Guillermo Paniagua ◽  
Donald Ferguson
Keyword(s):  
Pressure Ratio ◽  
Thermal Characterization ◽  
Navier Stokes ◽  
Computational Time ◽  
Efficiency Gain ◽  
Precise Knowledge ◽  
Potential Gain ◽  
One Step ◽  
Turbine Design ◽  
Rotating Detonation

Abstract Cycle benefits of rotating detonation engines show up to five percentage points of efficiency gain for low-pressure ratio engines. An optimal integration between the combustor and the turbine needs to be guaranteed to realize this potential gain. The rotating detonation combustor (RDC) exhausts transonic flow with shocks rotating at frequencies ranging from a few to tens of kilohertz depending on the number of present waves. Hence, the turbine design requires precise knowledge of the fluctuations and losses downstream of the combustor. This paper focuses on the quantification of fluctuations and losses for accelerating and diffusing passages. The analysis of the combustor is performed via reactive unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. The unsteady RANS equations are solved via CFD++ from Metacomp with a one-step reaction mechanism for an H2-air mixture. The resolving of the boundary layer is achieved with a structured mesh of around 36 million cells. Inlet pressure of 10 bar and two different back pressures are applied to the combustor to model the interconnection with downstream turbines. Finally, we present and assess a methodology to reduce the computational time to model these passages ten times.

scholarly journals Hydrodynamic Response of a Combined Wind–Wave Marine Energy Structure

2020 ◽  
Vol 8 (4) ◽  
pp. 253 ◽  
Author(s):  
Yapo Wang ◽  
Lixian Zhang ◽  
Constantine Michailides ◽  
Ling Wan ◽  
Wei Shi
Keyword(s):  
Renewable Energy ◽  
Wave Energy ◽  
Offshore Wind ◽  
Hydrodynamic Performance ◽  
Energy Structure ◽  
Marine Energy ◽  
Floating Offshore Wind Turbines ◽  
Central Column ◽  
Combined Structure ◽  
Heave Motion

Due to the energy crisis and greenhouse effect, offshore renewable energy is attracting increasing attention worldwide. Various offshore renewable energy systems, such as floating offshore wind turbines (FOWTs), and wave energy converters (WECs), have been proposed and developed so far. To increase power output and reduce related costs, a combined marine energy structure using FOWT and WEC technologies has been designed, analyzed and presented in the present paper. The energy structure combines a 5-MW braceless semisubmersible FOWT and a heave-type WEC which is installed on the central column of the semisubmersible. Wave power is absorbed by a power take-off (PTO) system through the relative heave motion between the central column of the FOWT and the WEC. A numerical model has been developed and is used to determine rational size and draft of the combined structure. The effects of different PTO system parameters on the hydrodynamic performance and wave energy production of the WEC under typical wave conditions are investigated and a preliminary best value for the PTO’s damping coefficient is obtained. Additionally, the effects of viscous modeling used during the analysis and the hydrodynamic coupling on the response of the combined structure are studied.

Numerical Analysis of a Floating Body With Two-Dimensional Moonpool Including Piston Mode

2010 ◽  
Author(s):  
Jaekyung Heo ◽  
Jong-Chun Park ◽  
Moo-Hyun Kim ◽  
Weon-Cheol Koo
Keyword(s):  
Free Surface ◽  
Viscous Flow ◽  
Experimental Results ◽  
Floating Body ◽  
Navier Stokes ◽  
Linear Potential ◽  
Navier Stokes Equation ◽  
Nonlinear Potential ◽  
Heave Motion ◽  
Piston Mode

In this paper, the potential and viscous flows are simulated numerically around a 2-D floating body with a moonpool (or a small gap) with particular emphasis on the piston mode. The floating body with moonpool is forced to heave in time domain. Linear potential code is known to give overestimated free-surface heights inside the moonpool. Therefore, a free-surface lid in the gap or similar treatments are widely employed to suppress the exaggerated phenomenon by potential theory. On the other hand, Navier-Stokes equation solvers based on a FVM can be used to take account of viscosity. Wave height and phase shift inside and outside the moon-pool are computed and compared with experimental results by Faltinsen et al. (2007) over various heaving frequencies. Pressure and vorticity fields are investigated to better understand the mechanism of the sway force induced by the heave motion. Furthermore, a nonlinear potential code is utilized to compare with the viscous flow. The viscosity effects are investigated in more detail by solving Euler equations. It is found that the viscous flow simulations agree very well with the experimental results without any numerical treatment.

Ship Hull Form Optimization Using Artificial Bee Colony Algorithm

2014 ◽  
Author(s):  
Fuxin Huang ◽  
Lijue Wang ◽  
Chi Yang
Keyword(s):  
Drag Reduction ◽  
Artificial Bee Colony ◽  
Interpolation Method ◽  
Ship Hull ◽  
Mathematical Functions ◽  
Hull Form ◽  
Abc Algorithm ◽  
Bee Colony ◽  
Hull Forms ◽  
Fast Flow

In this paper, artificial bee colony (ABC) algorithms are introduced to optimize ship hull forms for reduced drag. Two versions of ABC algorithm are used: one is the basic ABC algorithm, and the other is an improved artificial bee colony (IABC) algorithm. A recently developed fast flow solver based on the Neumann-Michell theory is used to evaluate the drag of the ship in the optimization process. The ship hull surface is represented by discrete triangular panels and modified using radial basis function interpolation method. The developed optimization algorithms are first validated by benchmark mathematical functions with different dimensions. They are then applied to the optimization of DTMB Model 5415 for reduced drag. Two optimal hull forms are obtained by the ABC and the IABC algorithms. A large drag reduction is obtained by both of the algorithms. The optimal hull form obtained by the IABC algorithm has larger drag reduction than that of the hull form from the ABC algorithm. The results show that two ABC algorithms can be used for optimizing ship hull forms and the IABC algorithm has better performance than the ABC algorithm for the tested case in ship hull form optimization.

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