High-speed Craft Research Articles

Study on the influence mechanism of elastic appendage on the longitudinal stability of high-speed planing craft

Aiming at the problem of porpoising during high-speed navigation of planing crafts, this study designed a localized elastic appendage installed in the high-pressure area of the boat bottom, which can improve the longitudinal stability of the planing craft through its passive deformation. The ship model towing test and numerical simulation of rigid model (RM) and local elastic model (LEM) are carried out under still water conditions. The flow field calculation of RM based on CFD and the two-way fluid-structure interaction simulation of LEM based on CFD-FEM are all in good agreement with the experimental data. The test and numerical results indicate that in the speed range of 1–11 m/s, the maximum deformation of the LEM elastic appendage can approach 4 mm. There is an obvious improvement in longitudinal stability following deformation. The stable speed range is increased by 1.2 times and the trim angle of LEM is reduced by a maximum of 15% when compared to RM at the same speed. In terms of resistance, RM and LEM exhibit almost identical characteristics. Based on the details of flow field and the pressure distribution obtained by the numerical simulation, the mechanical properties of the planing craft after the deformation of the local elastic appendage have been analyzed, which provides a new design idea for the planing craft to improve the longitudinal stability.

Determining the aerodynamic performance of a high-speed unmanned marine wig craft

The study object of this paper is the aerodynamic processes during the movement of an unmanned aerial vehicle flying low over the underlying surface. The ground effect is known to enhance the aerodynamic performance of low-flying aircraft, particularly larger ones. However, this effect is most noticeable for large objects. Unmanned vehicles are typically characterized by their relatively compact geometry. This study explores the aerodynamic processes involved in the flight of a small-sized vehicle using the principle of dynamic support over a surface. The particular prototype of the unmanned aerial vehicle suggested by the authors has been examined herein. The aim of the study is to evaluate the aerodynamic forces affecting a small-sized unmanned high-speed vehicle that employs the dynamic principle of support over the surface (WIG craft) by using CFD modeling. In contrast to most available studies on the ground effect, a 3D problem statement was used in this work. Computational experiments have visualized the physical fields surrounding an aircraft in flight over the ground. This study determines how the distance from the surface affects the aerodynamic properties of a small-sized aircraft, as well as the height of the effective zone where ground effect influences the small-sized WIG craft within . It has been shown that approaching the surface leads to a shift in the center of pressure of the vehicle, which leads to a change in aerodynamic momentum. This phenomenon must be taken into account when designing a control system to provide a stable flight. The study's findings are directly relevant for the development of a type of unmanned vehicles that use the dynamic principle of support over the surface.

6DoF CFD Analysis for High-Speed Small Craft in Free Running Conditions

ABSTRACT CFD simulations of a high-speed small craft are performed with 6DoF motions. The hull form and propulsor are scaled to match a deep V fishing boat (DVFB). The on water experimental data of the DVFB was used for qualitative validation. Many captive and free running conditions are considered including some most critical conditions, such as 2DoF captive motion, free running self-propulsion, turning circles in calm water and waves, acceleration, and avoidance line tests. The present work is the first known CFD study for the free running of high-speed small craft with 6DoF motions and is exploratory in nature. The accuracy and performance of the gear case and propeller models are evaluated with the issues identified. Other issues are also discussed including the optimum grid sizes, submerged depth of the gear case, and instabilities. All of these can be provided as recommendations for the future research improvements.

Evaluation of Strategic Intelligence on Countering Smuggling Threats Using High Speed Craft

Evaluation of Strategic Intelligence on Countering Smuggling Threats Using High Speed Craft

Free-Running tests for the rapidity of the aerodynamic lift-increasing planing craft

Free-running model test is one of the main test methods to study the performance of ships. In this study, a free-running test model was designed based on the planing trimaran model. The test model has a propulsion system and a data acquisition system, which can complete the functions of remote control, collecting thrust value and speed data and remote transmission data. Two kinds of wings were added to the test model, including the canard wing and the main wing. The test mainly studied the influence of the aerodynamic lift generated by the canard and the main wing on the rapidity of the planing trimaran. The test results show that with the increase of speed, the wing structure can produce considerable aerodynamic lift, and the purpose of reducing drag can be achieved by changing the pitch of the hull and lifting the hull. The test results verify the feasibility of using aerodynamic lift to improve the rapidity of high-speed planing craft. The combination of canard and main wing at the optimal attack angle can reduce hull resistance by 16.5 %.

Safety Improvements for High-Speed Planing Craft Occupants: A Systematic Review

Moving fast by high-speed planing craft (HSPC) is advantageous for some special missions, though it causes severe hull vibrations and shocks that can transfer to the human body and increase health and comfort risks. This study reviews the current safety standards to avoid human safety risks affected by whole-body vibrations (WBVs), as well as the safety status of HSPC occupants. In addition, the efficiency of motion-reduction devices (trim tab and interceptor) and shock/vibration-mitigation devices (shock-mitigation seat) in improving the safety of HSPC occupants is examined according to existing documents. The research methodology was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRIS-MA) method, and published papers in the Scholar, Scopus, and Web of Science databases were analyzed. Because most of these publications are academic research, issues of bias in the eligible publications were not of particular interest. During this systematic review, many gaps and challenges in current information on safety improvement devices were found that need to be addressed in future studies, such as a lack of information on motion-reduction devices and shock-mitigation seat performance in reducing lateral and fore-and-aft motions. Referring to these gaps and challenges can be valuable as a suggestion to improve current knowledge in research and reduce safety risks.

Effects of the abdominal belt on the reduction of spinal forces and muscle activities during extreme transits of high-speed craft

Repeated high-g shocks and whole-body vibration (WBV) as experienced by operators of High-Speed Craft (HSC) increase the risk of fatigue, back pain, and acute and chronic injuries, especially in the lumbar region of the spine. Studies on abdominal belts have suggested their beneficial effects on lumbar torso stabilisation and back pain mitigation in both weight lifting and HSC scenarios. This paper presents a human musculoskeletal model to simulate belt effects for occupants on HSC under high-g shocks. Parameters included the shock severity with peak acceleration ranging from 3 g to 10 g, human dimensions and muscle strengths, the belt width and belt forces are investigated. The results show an average of 120% increase in the intra-abdominal pressure (IAP), a 9% reduction in the transverse abdominis activities, and a 12% reduction in the spinal compressive force at the L4/L5 joints when the abdominal belt is added to the human model. In conclusion, wearing an abdominal belt significantly assists abdominal muscles and maintains a solid core during intense WBV generated in different shock severity levels. It may cause a small negative influence on the neck region with a 2.4% increase in the shear force at the C4/C5 joints.

Numerical Research on Impacting Load and Structural Response for a Model Experiment of High-speed Craft

Abstract High-speed craft generally applies hy droplane boat-type and large power engine to obtain high speed in water as results that significant hydrodynamic nonlinearities, high-speed craft has complex the impact load characteristics and structural response which attract considerable attentions of ship mechanics researchers. This paper studies impacting load and structural response of a high-speed craft by means of numerical approach coupling CFD and FEM. A model experiment of high-speed craft is selected to simulate impact load and structural response, the craft model consists of two ship bodies and a keel beam, a number of pressure sensors and strain gauges are arranged to capture the impacting pres s ure and VBM. A numerical FSI approach coupling CFD and FEM is used to study the model experiment of the high-speed craft. CFD is used to solve the hydrodynamics of the high-speed craft, DFBI and overset grid algorithm are employed to simulate the craft motion. Dy namic FEM is us ed to calculate structural response of high-speed craft, structural VBM is obtained. Two-way FSI is employ ed to realize coupling of CFD and FEM, wave pres s ures and structural displacement are iterated to progress. At last, numerical res ults and experimental res ults including impacting pressure, craft motion and VBM are compared and analyzed, they agree with closely. The numerical approach can be used to study the impacting load and structural respons e for high-speed craft.

Novel dimensionless parameters in 2D wedge drop

ABSTRACT The aim of this research is to create new dimensionless relations in rigid wedge impact problems, which provides the possibility of calculating wedge kinematic parameters with acceptable accuracy. To accomplish this, the rigid wedge impact problem is simulated and validated using the Dynamic Fluid Body Interaction (DFBI) model in STAR-CCM+. In this study, new non-dimensional relations for the kinematical parameters of the wedge are derived utilising the Buckingham π theorem and data-driven analysis. It is observed that the use of appropriate dimensionless relations in any type of symmetric water impact problems involving a wedge shaped object will result in a unique diagram of each wedge kinematical parameter. This ultimately leads to the creation of two separate formulas to determine the maximum wedge acceleration value and its corresponding time. These formulas play a vital role in the design of high-speed crafts, and planing vessels.

Assessment of Seafarers’ Mental Workload: A Study on High Speed Craft

High speed craft has become prominent in maritime industry. Sophisticated electronic navigation equipment on bridge increases mental demands of high speed craft navigator. In the present study, mental workload of high speed craft navigators has been assessed in terms of bridge navigation operations. For this purpose, the pairwise comparison of the effects of Electronic Chart Display and Information System, Automatic Radar Plotting Aid, Automatic Identification System and autopilot on mental workload and Revised NASA Task Load Index questionnaires were carried out. High speed craft navigators sorted berthing, unberthing, navigation in coastal waters, navigation in restricted waters, and navigation on open sea operations according to their mental workload levels. In addition, they indicated the factors mostly affecting mental workload and the remarkable suggestions to keep the optimum level of mental workload. As result of these findings, considerations have been made for increasing the safety of high speed craft navigation.

Linear and nonlinear analyses of the porpoising dynamics of high-speed planing craft using full-scale trial data

Linear and nonlinear analyses of the porpoising dynamics of high-speed planing craft using full-scale trial data

Numerical Investigation of Bottom Step Height Effect on The Hydrodynamic Performance of High-Speed Planing Crafts

Numerical Investigation of Bottom Step Height Effect on The Hydrodynamic Performance of High-Speed Planing Crafts

Analysis of the double steps position effect on planing hull performances

Along with developing high-speed craft technology, the planing hull is growing with modifications for better performance. One such technology is stepped hull, both single and double. Planing hull with steps allows the boat to run at a relatively low drag-lift ratio with lower frictional resistance due to reduced wetted area. In this study, the hull was modified with variations in the position of the double steps, which aimed to determine the effect of the first and second step positions on the total resistance, dynamic trim, and dynamic sinkage generated by computational fluid dynamics (CFD). Based on the analysis results, variations in the position of the stepped can change the hull performance. Shortening the distance between the two steps and moving both rearwards toward the transom can lower the total resistance. The dynamic trim and dynamic sinkage decreased as the position of the two steps was shifted further forward. An equation created in a non-dimensional form relates the positions of two steps to the desired results of total resistance, dynamic trim, and dynamic sinkage, namely: {(x1-x2)/L + (x1x2)/(LB)} × Fr∇, where x1 is distance the first step from transom, x2 is the distance of the second step, L is the length of the boat, B is the beam of the boat, and Fr∇ is the volume Froude number.

Numerical parametric assessment of the effects of stern wedges on the pressure and friction resistance of high-speed craft

ABSTRACT In the current study, wedge effects on a planing hull's friction and pressure resistance components have been numerically investigated. This study also assesses how the variation of pressure and friction resistance components can be predicted by trim angle variation. The obtained results indicate that at F r b < 0.9 , stern wedges slightly increase the vessel's pressure resistance. By increasing the speed, pressure, and friction resistance components of the wedge-mounted model descends and increases, respectively, compared to the baseline model. The results indicate that the wedge-mounted planing hull experience a decrease in pressure resistance of up to 27% and an increase in friction resistance of up to 34%. After F r b = 2.15 , some interaction effects between the wedge length and height on the total and pressure resistance appear. The findings also indicate that wedge effects on the planing hulls' pressure and friction resistance components are much different from those of displacement hulls.

An attempt to predict planing hull motions using machine learning methods

Designing a high-speed craft for better seakeeping in waves can contribute significantly to higher safety and human comfort. Early in the design process, mathematical models such as the 2D+T method are commonly used, while high-fidelity computational fluid dynamics (CFD) and experimental models are used later in the process. Some of the limitations of such models are that they are not fast enough to be used in the ship’s system for real-time monitoring or to develop a digital twin. Recently, machine learning methods have demonstrated great promise in building surrogate models from data. These methods include deep learning and recurrent neural network (RNN). In this paper, a systematic investigation of the network architectures and the used optimizers to train the network is presented. Adam, Adagrad, RMSprob and SGD are investigated in training the network. To train the model almost 35000 data points were collected for Fridsma hull operating in 18 regular waves using a 2D+T model. The result showed that gated recurrent unit (GRU) outperformed long short-term memory (LSTM) and RNN in predicting the heave motion. Also, one hidden layer with 5 neurons was enough to achieve mean absolute error of 0.000298 and to predict unseen waves when trained with more than 24000 data points.

Sensitivity of Mass Distribution with Respect to Pitch Motions of High-Speed Craft

Beside of environmental conditions, ship characteristics also greatly affect in ship behavior when operating at sea, called seakeeping ability. The shape of the hull, appendages, damping, and the weight distribution of ship are some of the factors that determine how the ship motion response occurred. This paper examines how much the pitch motion is influenced in high-speed craft due to the changing of the gyration radius. By using the strip theory method, and by taking the irregular head sea condition and a wave height of 4 meters, then the ship speed and the wave period are varied to determine the pitch motion amplitude at 3 values ​​of gyration radius: 0.2, 0.25 and 0.3 of the ship's length. The results of the study show that at higher ship speeds, the gyration radii greatly influence the pitch amplitude. As for changes in the wave period, the influence is significant at value of 5 second. From these two results, it is clear that the ship's gyration radii must be determined precisely to be able to predict an accurate pitch motion response on a high-speed craft.

Dimensional Characteristics of the Simulator Steering Wheel of LSF-2 High-Speed Landing Craft by SLA Additive Manufacturing and Reverse Engineering

Dimensional Characteristics of the Simulator Steering Wheel of LSF-2 High-Speed Landing Craft by SLA Additive Manufacturing and Reverse Engineering

An Experimental Study on the Resistance of a High-Speed Air Cavity Craft

For the marine industry, resistance reduction can reduce energy consumption and achieve protection of the marine environment. The use of air lubrication to reduce the resistance of ships is one of the most important ways. With this technology, high-speed air cavity crafts show immense potential as they can be utilized in various marine activities, such as emergency rescue, supply, and maritime security. Through experiments, this study presents an in-depth analysis of the effects of bubble chamber pressure and initial stern inclination on the resistance of high-speed air cavity crafts at different speeds. The results show that air pressure has a significant impact on resistance. It was found that as the speed of the ship increased, the resistance reduction effect became more prominent under the same pressure conditions. Moreover, the resistance tended to stabilize when the pressure reached a certain value. In addition to the air pressure, the longitudinal inclination does have an effect on resistance reduction. To achieve better resistance reduction, the initial stern inclination angle should be chosen appropriately. Furthermore, adjusting the angle with speed changes can optimize the resistance reduction effect. This experimental study provides critical support for conducting further research on high-speed air cavity crafts. The findings offer valuable insights into improving hull forms, guiding host selection, and assessing performance.

Investigation of the optimum longitudinal single transverse step location for a high-speed craft

One of the crucial aspects of the conceptual design of a stepped planing hull is the prediction of its performance. To improve performance, the prediction of total resistance must become more accurate. In the field of research, both towing tank experiments and numerical analysis may be used to achieve this goal. In this study, experiments were conducted initially to investigate total resistance of a relatively high-speed craft without a transverse step. Later, numerical computations were carried out to validate the experimental results. After it was determined that the test results and CFD methods were in good agreement, the experimental method continued to investigate the resistance properties of the hull with four different configurations to evaluate the optimal longitudinal position of a single transverse step. The ideal longitudinal position of the single transverse step was evaluated based on a similar relatively high-speed hull with a velocity of up to beam Froude number (FrB) 2.56 in this study, focusing on the FrB range between 2.30 and 2.45.

A Study of the Resistance Components of Planing Hull Using Interceptors

The extreme motions created a negative effect on planing hull. Otherwise, interceptors enable the improvement of hydrodynamic characteristics of the highspeed craft. The total drag of the ship can be divided into two components: pressure and shear forces. This project specifically aims to predict the drag component based on CFD simulation with and without an interceptor based on resistance components. The volume of fluid is used in a compound with a RANS solver to determine drag and trim in calm water conditions. SIMPLE algorithm using overset mesh and DFBI was modeled free in heave and pitch to simulate the rigid body motion as a response to shear and pressure drag exerted by the fluid. A grid independence study has been used to predict uncertainties using time-step and grid spacing. Additionally, to guarantee to proceed with the simulation, ITTC recommendations had been followed. The benchmark study was undertaken as an experimental comparison by Park et al. In general, ship performance was controlled by pressure force in the displacement phase and planing phase, the shear and pressure forces are balanced. The interceptor can decrease the pressure force by 5% in the hump region and planing phase.