Ship Performance Research Articles

Effect of Propeller Face Camber Ratio on the Reduction of Fuel Consumption

This paper presents the effect of the face camber ratio (FCR) on propeller performance, cavitation, and fuel consumption of a bulk carrier in calm water. First, using a developed propeller optimization model coupling a ship performance prediction tool (NavCad) and a nonlinear optimizer in MATLAB, an optimized propeller design at the optimal engine operating point with minimum fuel consumption is selected. This optimized propeller demonstrates superior fuel efficiency compared to the one selected by using the traditional selection methods that prioritize only higher propeller efficiency. Afterward, the FCR is applied to the propeller geometry to evaluate the effect on propeller performance. The open water curves of propellers with different FCRs ranging from 0% to 1.5% are computed based on empirical formulas and computational fluid dynamics (CFD) simulations. Between the two techniques, a good agreement is noted in verifying the predictions. Then, the open water curves from CFD models are implemented into NavCad to evaluate the overall hydrodynamic performance of the propeller at the design point in terms of efficiency, quantify reductions in fuel consumption, and analyze changes in cavitation and noise criteria. The computed results show a reduction in fuel consumption by 3% with a higher FCR. This work offers a preliminary evaluation of propeller performance-based FCR and shows its benefits. This technique offers a promising solution for improving the energy efficiency of the ship and lowering the level of fuel consumption and exhaust emissions.

Optimization design of a windshield for a 12,000 TEU container ship based on a support vector regression surrogate model

This study presents the design of a windshield for a 12,000 TEU container ship using a multidisciplinary optimization system aimed at enhancing its aerodynamic performance. The framework integrates parametric modeling, design of experiment (DOE), numerical simulation, support vector regression (SVR)-based approximation, and a genetic algorithm (GA). Initially, the flow field around the ship is predicted using Reynolds-averaged Navier–Stokes (RANS) equations, with accuracy validated against computational fluid dynamics (CFD) and experimental fluid dynamics (EFD) results. The windshield’s shape is then defined by three Bezier curves, and six design variables are selected based on these curves to ensure smooth deformation. Subsequently, 120 sample points are chosen within the design space using the DOE method, and an SVR-based surrogate model is established. Optimization is performed using the multi-island genetic algorithm to determine the windshield configuration. Validation tests confirm the robustness of the optimization process. On this basis, the drag reduction mechanism of the windshield is summarized and analyzed. Results demonstrate that the optimization system effectively enhances the aerodynamic performance of the container ship, achieving a maximum drag reduction rate of 20.67% under headwind conditions and significant improvement across wind angles from 0° to 60°.

ПРИМЕНЕНИЕ ИННОВАЦИЙ НА МОРСКОМ ТРАНСПОРТЕ НА ПРИМЕРЕ KYMA SHIP PERFORMANCE

This article discusses an innovation in the field of maritime transport – Kyma Ship Performance, designed to monitor the overall performance of the vessel, allowing shipowners to significantly save fuel costs.

The Effect of Changing the Beam of an Ancient Ship’s Hull on Its Capacity, Stability, and Performance

Wooden ships on the shipwreck sites are usually only partially preserved, and reconstructing the original hull lines requires considerable effort. The shape of the hull has a direct effect on the ship’s capacity to carry cargo, as well as on its speed and stability. When reconstructing the hull lines, the incomplete nature of the archaeological remains results in the interpretation of the available data. The outcome, therefore, depends on the assumptions and decisions associated with the reconstruction process. This paper examines how the variation in a single parameter, namely, the beam, affects the performance of the vessel. Considering the availability of the model, the Kyrenia ship from the fourth/third century BC is used as a case study. The scope of this paper is to demonstrate and quantify the effect of beam variation on ancient ship performance, namely, the ship cargo capacity, stability, and resistance. Kyrenia ship was used as a study case based on hull lines proposed by Steffy in 1985. The aim is not to modify Steffy’s original reconstruction but to demonstrate that small deviations could significantly affect the performance of the vessel. In addition, an increase in the height of the ship’s sides is proposed as a possible solution to increase the load capacity of the ship. The opportunity to explore a whole set of trials and reconstructive variations with naval engineering software can deepen our understanding of ship performance, allowing us to improve our approach to reconstruction, too.

Effect of multiple appendages on maritime surveillance ship resistance at various ship speeds

Resistance is a critical factor affecting the operational performance and economic efficiency of marine surveillance ships. To enhance the enforcement efficiency of marine surveillance ships, this study investigates the impact of five types of appendages on ship resistance performance. In this study, resistance experiments and numerical simulation calculation on the ship model were carried out. Based on Computational Fluid Dynamics (CFD) and the Volume of Fluid (VOF) method, the study captures the variations in ship resistance and the free surface Cases around the hull. A comparative analysis was then conducted on the resistance effects of different appendages installed on the ship model. It was found that the installation of stern shaft brackets, bilge keels, and ductkeel increased the ship's resistance. In contrast, the installation of spray rails reduced resistance by approximately 2.5%. However, the effectiveness of the spray rails diminished at high speeds due to their inability to prevent wave overtopping. Since stern flaps are commonly used drag-reducing appendages, this study improved the original design. Comparative analysis revealed that the modified curved structural design of the stern flaps exhibited enhanced drag reduction capabilities.

Research on Course-Changing Performance of a Large Ship with Spoiler Fins

The poor maneuverability inherent to large ships is a non-negligible problem that restricts the development of the shipping industry, as large ships can only cruise at an excessively conservative speed when they encounter complicated traffic conditions; nevertheless, ship collision accidents still occasionally occur. In the present study, the novel concept of spoiler fins for modern large ships is proposed. In order to assess their effectiveness in enhancing ship maneuverability, a KRISO container ship (KCS) was selected to carry a pair of spoiler fins, after which a simplified simulation approach for saving the calculation resource was designed for ship collision avoidance conditions, and a full-scale numerical model, including the ship hull, fin, and fluid field domain, was established. Transient-state hydrodynamic forces were calculated during collision avoidance maneuvers using the CFD method; the pressure and velocity contours around the ship were demonstrated; and the ship motion trajectories under different initial ship speeds were simulated and predicted through the adoption of overset mesh and 6-DOF dynamic mesh techniques. Eventually, the improved course-changing performance, dependent on the spoiler fins, was validated.

Enhanced Output Performance of Two-Level Voltage Source Inverters Using Simplified Model Predictive Control with Multi-Virtual-Voltage Vectors

Interest in electric propulsion ships has garnered attention to reduce ship exhaust emissions. This has sparked extensive research on inverters. While two-level voltage source inverters are commonly utilized in small- and medium-sized ships owing to their simple structure and cost-effectiveness, they have limitations, such as high switching losses and reduced output performance. To address these issues, a model predictive control technique based on virtual voltage vectors is proposed in this study. Conventional two-level voltage source inverters are restricted to using only eight voltage vectors, which limits their output performance. By incorporating virtual voltage vectors, similar performance to multilevel converters can be achieved. The proposed technique involves a pre-voltage selection method that enhances output performance without increasing computational load. Through simulation and experiments, improved output current THD and current error were observed under various load conditions. This showcases the potential for enhancing the efficiency and performance of electric propulsion ships.

Comparative Analysis on the Effect of Bow Shapes on the Ship Resistance using CFD Simulation and Model Test

Shipping companies and ship owners are very concerned with reducing operating costs. One way to achieve this is by improving the hydrodynamic performance of ships, which can reduce fuel consumption by decreasing total resistance. Optimizing ship design, particularly the bow shape, is crucial for enhancing hydrodynamic performance, fuel efficiency, and operational costs. While CFD simulations have become a powerful tool in naval architecture, their accuracy and reliability in predicting hydrodynamic resistance for different bow shapes need validation through experimental data. This study employs computational tools using Fine/Marine NUMECA and model tests carried out in a towing tank. The primary objective is to compare the hydrodynamic resistance of axe bow and conventional bow shapes. Additionally, the contributions of different resistance components (residuary and friction) to each bow shape are identified and quantified. The study concludes that the axe bow shape offers notable improvements in reducing total resistance compared to the conventional bow, providing a reduction of up to 12.5%. Moreover, the residuary resistance component has a more significant effect on total resistance compared to friction resistance.

Big Data Analysis of the Speed Performance of a 176k DWT Bulk Carrier in Real Operating Conditions

Assessment of ship performance under in-service conditions is challenging due to the complex effects of many environmental disturbances. ISO 15016 and ISO 19030 standards are commonly used to evaluate ship operating performance. However, ISO 15016 requires numerous variables, a complex calculation formula, and considerable time and cost, and ISO 19030 only evaluates the reduction of ship speed caused by wind and neglects the effect of waves. To improve both standards and achieve a more accurate ship performance assessment, this study proposes a new performance prediction model, the multi-input single-output (MISO) system, which assumes that each ship has specific frequency characteristics according to type and size. Based on this new model, in-service navigation data collected from a 176k DWT bulk carrier, which amount to 5.7 million data points, are analyzed to assess the speed performance of the vessel subject to environmental disturbances. The proposed model was validated by comparing its results with ISO 19030 and specifically assessing the speed–power curves and speed reduction measured in operational data with the influence of environmental disturbances removed.

Enhancing Efficiency in Deep-V Planing Hull Ships: A Study on The Design of Spray Strips to Minimize Resistance

Spray strips are deflectors installed on the hull to decrease the wetted surface area (WSA). By reducing the WSA, the overall resistance of the ship is lowered because it lessens the friction of water flowing against the hull. The purpose of this research is to predict the function of spray strips in an effort to improve ship performance. In this study, the numerical methodology employs the Finite Volume Method (FVM) along with the Reynolds-averaged Navier-Stokes equation (RANS) for resolving fluid dynamics issues. The modeling of the two-phase flow involves the utilization of both the Volume of Fluid (VOF) model and the Eulerian model. The results of this study show that spray strips can reduce the total resistance by about 2.7%. Increasing the number of spray strips can reduce the drag shear value by 3.5%. Spray strips are effective in reducing total drag when the Froude number (Fr) is greater than 1 or when the vessel is in the planing phase. The profile shape of spray strips with dimension 2:1 shows the best performance on ship resistance.

Measurement of sound perception to improve the performance of military ships

The performance of military ships relies on the performance of equipment and operators. Acoustic performance of military ships consists of: - the acoustic discretion of the vessel, allowing a strategical advantage in the event of a threat (more specifically: noise and vibrations management of ship sources); - the acoustic comfort of the operators in the ship, allowing better oral communication, better perception of safety alarms and a better focus. These effects can reduce time loss, and prevent operators from making errors. It is therefore important to manage the acoustic environment on board throughout the design process, in order to ensure both the acoustic discretion of the ship and the performance of its operators on board. For several years, Naval Group is interested in optimizing the performance of the operators, coupling both acoustic and visual perceptions through virtual reality (VR). This congress is an opportunity to expose recent works on acoustic perception in a ship. Our results are based on both numerical simulations and experimental measurements.

Assessing the reliability of a ship energy performance simulation tool through on-board data

To mitigate the environmental impact of shipping on climate change, it is nowadays urgent to explore energy efficiency and cost-effective measures by means of reliable digital tools. These are becoming essential for assisting the design of new ships and the refurbishment of the existing ones, as well as for assessing and optimizing the energy performance of a ship during its entire life-cycle. This paper focuses on the verification of the reliability of a novel ship energy dynamic simulation tool, developed for the calculation of the energy, economic, and environmental performance of large ships, the design and optimization of energy system layouts and operational logics, as well as the definition of design and management guidelines for ships. The reliability of the developed model was verified through the use of data measured onboard an existing sample cruise ship. The verification procedure is conducted for assessing the reliability and for exploiting the potentiality of dynamic analysis for a more precise evaluation of ships energy loads, temperature levels, and necessary sizes of possible saving technologies. The validated tool will enable reaching two different goals: i) to evaluate different energy system layouts and to define the optimal one for achieving the present imposed targets and constraints, ii) to obtain a large amount of data for allowing the implementation of the digital twin approach in the maritime sector. The model validation was successfully achieved and very low or negligible deviations, lower than 4%, of numerical data vs. measurements were observed. Through the validated simulation tool approximately 23.4 GWh of primary energy from polluting fuels over two weeks is computed. In addition, the model provided insights into the flow rate, temperature levels, and energy flows of the ship energy system, necessary for identifying the amount of thermal energy to be recovered as well as potential solutions to enhance the energy efficiency of the entire system.

Automatic Optimal Design Method for Minimum Total Resistance Hull Based on Enhanced FFD Method

Hull optimization plays a crucial role in enhancing ship performance and efficiency. This study aimed to improve ship performance, particularly by reducing total resistance, through automated optimization methods. To this end, an integrated, fully automated optimization program was developed based on Python, incorporating Enhanced Free-Form Deformation (FFD) technology, scripted CFD numerical evaluation, and the Particle Swarm Optimization (PSO) algorithm. This program allowed precise control of hull form, improving efficiency while reducing costs. The KCS hull, known for its excellent resistance performance, was chosen as the optimization target, with the goal of minimizing total resistance by adjusting the bulbous bow line plan. The research results indicated that the optimized scheme exhibited lower resistance characteristics compared to the original design while satisfying design constraints. This study not only provides a new optimization strategy for ship design but also lays a foundation for future hull optimization research.

Ship model-based route optimisation for decision support in deep sea shipping

Abstract We present a new approach and route optimization methodology to support analysis and planning of vessel and fleet performance in deep sea shipping for green, energy efficient, and safe navigation. The developed methodology combines the ship technical characteristics based on a ship model developed for a particular vessel type and energy-saving technology options and an optimization algorithm taking into account weather conditions. Optimization involves two stages: graph construction and Dynamic Programming labelling algorithm implemented to solve the shortest path problem with variable speed. The new approach is implemented as part of a decision-support tool EcoRouter enabling the user to conduct analysis of safe and Pareto optimal solutions. Several applications to support real fleet planning and ship performance analysis have been identified including project engineering for future energy-saving ship technologies, for example, wind-assisted propulsion.

Numerical simulation and analysis of motion responses and added resistance of a KRISO container ship in regular waves

Abstract In order to explore the influence of vessel speed on seakeeping characteristics and provide valuable insights for ship performance evaluation, the accurate prediction of ship motion and resistance in wave conditions is essential. In this study, the variations in ship motion and resistance with respect to ship speed are analyzed during navigation in regular waves. The results suggest that the added resistance coefficient of the KCS demonstrates an initial rise, succeeded by a subsequent decline, with the expansion of wavelength. Moreover, the peak non-dimensional resistance coefficient, observed at different ship speeds, demonstrates an upward trend with the augmentation of ship velocity. This research methodology provides a valuable tool for numerically predicting the hydrodynamic performance of vessels in regular wave conditions.

Study of the Characteristics of Ship Propulsion Systems with the Addition of a Kort Nozzle using the CFD Method

The component of a ship that affects its speed the most is its propulsion system, which includes a propeller. The propeller produces thrust by converting the blades' rotating force. A well-functioning propulsion system increases the propeller's effectiveness, which enhances the ship's performance. The addition of a kort nozzle to the propeller is one of the numerous methods currently available for enhancing its performance. These justifications serve as the foundation for this investigation. The purpose of this study was to compare the propeller's operating efficiency with and without a koert nozzle addition. The result of the research it was detected that there was an increase in thrust force after using the cort nozzle under the influence of calm water and wavy water by 15 ~ 30%. There is an increase in efficiency under the influence of still water. But under the influence of waves the value is not great. The resulting efficiency value is approximately 3 ~ 5% for the same RPM rotation efficiency.

An efficient method to simulate ship self-propulsion in shallow waters and its application to optimize hull lines

Emerging environmental challenges, such as pronounced low water levels and a constantly increasing transport volume, underscore the need to address logistical complexities and to refocus attention on the performance of self-propulsion vessels in restricted and confined waters. Recognizing the demand for an accurate and efficient ship design method, we modified an actuator disk model to predict ship propulsion. This model was designed to be applicable to various kinds of ships, with special features tailored to meet the specific requirements of inland water vessels, particularly those equipped with ducted propellers. We implemented this model into the open-source CFD software library OpenFOAM to be used in conjunction with either single- or multiphase incompressible solvers. We validated this implemented model against model test data, thereby demonstrating its capability to accurately predict propulsion performance of a typical inland waterway vessel. Following validation, we employed this model in an automated optimization process, demonstrating its robust and efficient applicability for a practical user-defined case to improve a ship's afterbody lines. Meticulous grid convergence studies ensured the predictive convergence of our simulations. Our validation covered various ship speeds at three distinct water depths, ranging from a moderate water depth-to-draft ratio h/T of 2.67 to an extreme shallow water depth-to-draft ratio h/T of 1.25. We validated our simulated results against data extracted from our own previous model tests, comprising measured ship trim and ship sinkage, propeller thrust, duct thrust, propeller torque, propeller revolution rate, and propulsion power. We investigated the influence of water depth also on various parameters, such as friction and pressure distributions, free surface interactions, and velocity patterns. Finally, we integrated the developed method into an automated optimization process that we tailored for a selected test cases of the considered ship operating in water depth to draft ratios h/T of 2.67. This integrated process facilitated the systematic refinement of the ship's afterbody lines, representing a crucial step in the pursuit to enhance ship performance.

Hydrodynamic performance of a high-Speed ship in waves using a fully nonlinear wave separation method

ABSTRACT A fully nonlinear time-domain simulation of a ship navigating in waves at high speed is realised by proposing a domain-split wave separation method. In the proposed method, a large distorted area of the free surface near the ship is split, on which the disturbed wave is separated by subtracting the incident wave from the total wave. For the rest of the free surface, the disturbed wave is traced by retaining the higher-order components. The present method is capable to simulate the strongly nonlinear interactions between the ship and waves, and can avoid unnecessary spurious waves. The present results are verified through comparison with experimental data. The steady VBM by navigation reaches its peak when the wavelength of the generated wave equals the ship length at the critical Froude number. The hydrodynamic behaviours of the S175 ship navigating in waves at this critical speed are investigated.

Optimization of Controllable-Pitch Propeller Operations for Yangtze River Sailing Ships

The Yangtze River’s substantial variation in water depth and current speeds means that inland ships face diverse operational conditions within a single voyage. This paper discusses the adoption of controllable-pitch propellers, which adjust their pitch to adapt to varying navigational environments, thereby optimizing energy efficiency. We developed an optimization framework to determine the ideal pitch angle and rotation speed (RPM) under different sailing conditions. The energy performance model for inland ships was enhanced to account for the open-water efficiency of CPPs across various pitch angles and RPMs, considering the impacts of current and shallow water, among other factors. The optimization approach was refined by incorporating an improved genetic algorithm with an annealing algorithm to enhance the initial population, applying the K-means clustering algorithm for population segmentation, and using multi-parent crossover from diverse clusters. The efficacy of the optimization method for CPP operations was validated by analyzing three operational scenarios of a Yangtze sailing ship. Additionally, key components of the ship performance model were calibrated through experimental tests, demonstrating an anticipated fuel consumption reduction of approximately 5% compared to conventional fixed-pitch propellers.

Voyage scheduling and energy management co-optimization in hydrogen-powered ships

The maritime sector is striving to lessen its dependence on fossil fuels, motivated by both economic factors related to fuel efficiency and the policies established by the International Maritime Organization (IMO). Consequently, there has been a growing focus on developing and deploying all-electric ships (AES) as a more sustainable alternative to conventional fossil fuel-powered vessels. AES presents several advantages over conventional ships, including zero emissions, enhanced energy efficiency, and greater sustainability. However, the implementation of AES also brings new challenges, such as the necessity to manage a hybrid microgrid and optimize voyage scheduling. Hybrid fuel cell (FC)-battery energy storage (BES) technology can significantly contribute to addressing these requirements. To tackle these challenges, this article introduces a comprehensive framework for the optimal planning of hybrid microgrids and voyage scheduling in AES. The framework incorporates multi-objective optimization techniques based on genetic algorithms to achieve a balance between cost and voyage time. The proposed framework is applied to a case study of a ship operating on a fixed route between two ports. The simulation results indicated that the total cost per voyage, associated with the objective function of cost minimization and voyage time reduction, has decreased by 12% and increased by 40%, respectively, when compared to the regular ship speed profile. Additionally, the travel time has been reduced by half an hour and 2 h, respectively, in comparison to the regular ship speed profile. To verify the results, the optimization problem for cost and voyage scheduling is also solved by Mayfly Algorithm (MA) separately. Thus, it can be illustrated the effectiveness of the framework in enhancing energy efficiency and fuel economy while preserving the ship's performance.