High-speed Planing 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.

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.

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

System identification of porpoising dynamics of high-speed planing craft using full scale trial data

Porpoise, a coupled heave and pitch oscillation, is one of the unstable behaviors in high-speed planing craft. To suppress porpoise, drivers respond by reducing the speed of the vessel. Active control using trim tabs has also been studied in the past. In order to suppress porpoise by actively controlling the trim angle of the outboard motor, this study develops a suitable motion model for this control. The following were studied in this paper: (1) a numerical motion model running straight for a planing craft with an outboard motor was proposed; (2) a method to identify the motion model based on the actual test results was proposed. In this paper, we conducted system identification based on experimental data using a representative craft. Accordingly, identification results that reproduced the occurrence of porpoise were obtained.

A Verification and Validation Study on a Loosely Two-Way Coupled Hydroelastic Model of Wedge Water Entry

_ The interaction between the structural response and hydrodynamic loading (hydroelasticity) must be considered for design and operation purposes of high-speed planing craft made of composites that are prone to frequent water impact (slamming). A computational approach was proposed to study the hydroelastic slamming of a flexible wedge. The computational approach is a loose two-way coupling between a Wagner-based hydrodynamic solution and a linear finite element plate model. Verification and validation (V&V) was performed on this coupled model. It was found that the model overpredicts rigid-body/spray root kinematics by <15% and hydrodynamic loading/ structural response by <26%. Introduction One of the primary constraints on the operational envelope of high-speed craft is slamming (water impact). Slamming occurs between the hull body and the water surface when a portion/whole of the craft exits the water and then reenters at high-enough velocity (Lloyd 1989; Faltinsen 2005). The frequent water impacts, which work like “water hammers,” along with their induced acceleration pose great jeopardy on hull structures as well as crew and instrument on-board (Yamamoto et al. 1985; Ensign et al. 2000; Hirdaris et al. 2014). With the growing use of lightweight materials, the interaction between the structural deformation and the hydrodynamic loading (hydroelasticity) becomes more prevalent. The current design criteria of high-speed craft are based on empirical procedures with no regard to hydroelasticity due to the lack of understanding of this complex phenomenon (DNV 2013; ABS 2016). Therefore, a better comprehension of hydroelastic slamming is the first step to designing more high-performance craft (Fu et al. 2014; Judge et al. 2020).

Mitigation of vertical motion in planing crafts for enhanced operationability in seaways using passive energy absorbers – A test of concept

High-speed planing crafts operating in seaways encounter high impact loads. The resulting extreme motions and accelerations adversely affect the craft's structural integrity and payload, and pose a risk to the onboard crew, thus limiting their year-round operability. Reducing the vertical acceleration and motions of these crafts in a seaway may ensure structural integrity, increase navigation safety, and extend their operational envelope. This study examines the effectiveness of deploying a linear passive energy absorber (PEA) – a tuned mass damper (TMD) – to mitigate the planing craft's vertical motion. Nonlinear equations of motion for the TMD installed on the planing craft operating in an irregular seaway were developed, and its effectiveness was evaluated and verified using numerical simulations. A significant reduction in the unwanted heave motions was observed around the sea states (SS) and the craft speeds used to fine-tune the TMD parameters. The effectiveness of the TMD, however, severely diminished in other SS and at other craft speeds. Based on our results, the application of the TMD to mitigate vertical motions of planing crafts seems an impractical solution. Other passive energy absorbers, such as nonlinear-PEAs or nonlinear energy sinks, should be considered as a way to address the TMD's shortcomings.

Numerical analysis of the impact of an inclined plate with water at high horizontal velocity

High-speed planing craft, aircraft when ditching into the water, and ground vehicles entering water can experience violent interaction with the water surface that leads to structural failure. The largest loads typically occur over a very short time, but the magnitude of the pressure and force can be extreme and important for design considerations of safe vehicles. In this paper the water entry problem is studied numerically with one-way and two-way-coupled fluid–structure interaction algorithms. One-way simulations assume a rigid structure while solving for the fluid domain solution, whereas the two-way-coupled approach captures the added mass effects by accounting for the plate deformation in the fluid solution. The primary objectives of this study are to present and validate the numerical methodology, and provide insight into the fundamental physical processes that are important for three-dimensional high-speed aircraft ditching and marine-vessel slamming problems. The fluid solution is obtained using the finite-volume discretization of the incompressible Navier–Stokes equations and the volume-of-fluid method to capture the air–water interface. The structural response is obtained using a modal decomposition representation of the dynamic finite-element system. The fluid–structure-interaction framework is validated by comparison with previously published experimental measurements of an aluminum plate that enters the water with a large horizontal-to-vertical velocity ratio. Several test conditions are discussed that ensure that the numerical solver can capture highly localized pressure maxima, the hydrodynamic force, the behavior of the jet-root propagation, and hydroelastic coupling. Simulation results show the capability to accurately capture these complex phenomena which are important to modeling water-entry problems for the design and certification of air-, land-, and water-craft.

Flow Visualization, Hydrodynamics, and Structural Response of a Flexible Wedge in Water Entry Experiments

_ In this article, a free-falling flexible wedge into calm water is experimentally studied to understand the relationship between the spray root, peak pressure, and structural response. High-speed cameras are employed to record the spray root propagation, whereas hydrodynamic loading is measured with an array of pressure transducers. Stereoscopic-Digital Image Correlation (S-DIC) is used to measure deflection on the bottom of the wedge during the impact. Experiments are conducted from different drop heights to study the effect of impact velocity. Results are interpreted in light of an experimental data set of a rigid wedge of comparable dimensions. The comparison between the rigid and flexible wedges shows that due to fluid-structure interaction, the evolution of the spray root on a flexible wedge is slightly delayed compared to the rigid one. Introduction Nowadays, high-speed planing craft are widely used in commercial, recreational, and naval applications. As the growth in utilization of these vessels is observed, naval architects strive to improve the overall performance while the safety metrics are adequately maintained. One of the major concerns that challenges both the performance and structural strength of small high-speed craft is hull slamming. Once the vessel is subject to incoming waves, the hull repeatedly becomes airborne and then impacts the water surface. These slams cause operators to reduce the speed, and the maneuverability of the vessel is also influenced. Additionally, slamming can lead to the serious injury of sailors in rough sea conditions. Severe motion of the vessel because of the impact may also adversely affect the operability of equipment on board, meaning that autonomous vessels are still vulnerable to these types of loading events. As a result, it is crucial to study and understand the slamming in high-speed craft in order to mitigate its negative effects.

A REAL TIME SPEED MODULATION SYSTEM TO IMPROVE OPERATIONAL ABILITY OF AUTONOMOUS PLANING CRAFT IN A SEAWAY

This study focuses on developing a control system to enhance the seaworthiness of Autonomous high-speed Planing Crafts (APCs). APCs operating at high-speed in a seaway encounter very high vertical accelerations which pose a hazard to payload and crafts' structural integrity. Therefore, for safety operation of APCs in a seaway it is proposed to employ a system termed vision-aided speed modulation system (VSMS). The proposed VSMS employs an embedded analytical tool termed Motion Assessment of Planing Craft in a Seaway (MAPCS) for the prediction of vertical accelerations and angular velocities, the APC might encounter in the incoming waves. As a response to the MAPCS predicted values the VSMS speed setting module modulates the craft's forward speed. All modules of the VSMS are presented together with their validation and system's preliminary operational results. It is concluded that VSMS might be an essential tool to considerably enhance the operational ability of APCs.

Speed–wave height operational envelope for high-speed planing craft in seaways: theoretical vs. empirical methods

ABSTRACT High-speed planing craft operating in real seaways encounter high impact loads. The extreme motions and accelerations resulting from such impacts adversely affect the structure of the craft and its payload as well as pose a risk to the crew on-board. Limiting craft speed according to the sea state using a speed-wave height operational envelope might ensure structural integrity and greatly improve safe navigation. Accurate estimation of motion and acceleration of planing craft in a seaway is a key requirement in developing reliable and usable allowable speed vs. wave height operational curves. In this paper, the Motion Assessment of Planing Craft in a Seaway (MAPCS) tool, a nonlinear time-domain approach vs. several existing approaches based on experimental, empirical and classification societies’ formulas for vertical accelerations and speed vs. wave height limit curves are compared. It is found that the MAPCS approach provides more realistic estimations compared to the commonly employed methods.

Vertical Wedge Drop Experiments as a Model for Slamming

_ A deeper comprehension of hydrodynamic slamming can be achieved by revisiting the wedge water entry problem using flexible structures. In this work, two wedge models that are identical, with the exception of different bottom thicknesses, are vertically dropped into calm water. Pressure, full-field out-of-plane deflection, strain, vertical acceleration, and vertical position are measured. Full-field deflections and strains are measured using stereoscopic-digital image correlation (S-DIC) and strain gauges. A nondimensional number, R, quantifying the relative stiffness of the structure with respect to the fluid load is revisited. An experimental parametric study on the effect of R on the nondimensional hydrodynamic pressure and the maximum strain is presented. It was found there is a sharp change in the trend of pressure and strain when R passes through a critical value. It was also discovered that the structural deformation causes a delay in the peak pressure arrival time and a reduction in the peak pressure magnitude during the wedge water entry. Introduction When high-speed planing craft operating in waves becomes airborne and reenters the water surface, a substantial impact or “slam” between the vessel bottom and the water surface will occur (Faltinsen 2005; Lloyd 1989). The bottom slamming events occur frequently and may injure the passengers, compromise the equipment onboard, or even damage the structure. Slamming is a major cause of speed reduction in small craft where slamming loads are important. Current design criteria are primarily based on empirical measurements with little regard for the fluid–structure interaction (FSI) physics of the slamming phenomenon. This study offers a first step toward better understanding of FSI in slamming for optimal structural design in the future. Since the cross sections of most surface effect ships may be approximated by a V-shaped wedge, the slamming characteristics of these sections may be examined by dropping a wedge model into water (Faltinsen 2005; Lloyd 1989). Studying the wedge water entry problem is also helpful in shedding light on the wet deck slamming of catamaran, sloshing under the chamfered roof of a partially filled tank (Faltinsen 2000), seaplane landing (Wagner 1932), water landing of spacecraft and solid rocket boosters, water landing/ditching of aircraft (Abrate 2013), and animal diving behavior (Chang et al. 2016).

Kinematic and inertial hydroelastic effects caused by vertical slamming of a flexible V-shaped wedge

Due to the increasing use of composite materials in high-speed planing craft prone to frequent slamming, the interaction between the structural response and hydrodynamic loading, hydroelasticity, must be considered. In this work, a V-shaped wedge model with 20° deadrise angle was vertically dropped into the calm water to simulate a typical hydroelastic slamming. With varied impact velocity and flexural rigidity of the wedge bottom plate a wide range of hydroelasticity factors, 0.1≤R≤6.4, were examined. Measurements included rigid-body kinematic motions of the wedge model, spray root propagation, hydrodynamic loading, and structural response. It was found that the maximum deflection and strain occur in the chine-unwetted phase in this study. The kinematic effect of hydroelasticity changes the spray root propagation and hence the pressure, while the inertial effect increases the natural period of the plate.

A Real Time Speed Modulation System to Improve Operational Ability of Autonomous Planing Craft in a Seaway

This study focuses on developing a control system to enhance the seaworthiness of Autonomous high-speed Planing Crafts (APCs). APCs operating at high-speed in a seaway encounter very high vertical accelerations which pose a hazard to payload and crafts' structural integrity. Therefore, for safety operation of APCs in a seaway it is proposed to employ a system termed vision-aided speed modulation system (VSMS). The proposed VSMS employs an embedded analytical tool termed Motion Assessment of Planing Craft in a Seaway (MAPCS) for the prediction of vertical accelerations and angular velocities, the APC might encounter in the incoming waves. As a response to the MAPCS predicted values the VSMS speed setting module modulates the craft's forward speed. All modules of the VSMS are presented together with their validation and system's preliminary operational results. It is concluded that VSMS might be an essential tool to considerably enhance the operational ability of APCs.

Experimental modelling of local structure responses for high-speed planing craft in waves

The modelling of planing craft dynamics in waves and related fluid-structure interaction is a hard challenge due to the highly nonlinear, transient and stochastic nature of the whole process. This paper explores the prospectives of detailed experimental modelling of the local structure responses for high-speed planing craft in waves. A novel experimental setup is presented where a well-defined model structure is integrated into the hull bottom of a typical planing craft model. The model is instrumented for measuring strains in the model structure, related slamming pressures, craft rigid body motions and accelerations. The experimental setup is thoroughly described and motivated and crucial aspects of the setup are verified through testing in idealized static loading conditions and by modal analysis. The capabilities of the experimental setup are demonstrated through systematic experiments in regular waves. The most indicative results are presented and discussed in relation to corresponding results from time-domain simulations. The presented experimental modelling approach is concluded to enable uniquely detailed studies of the complete slamming related fluid-structure interaction process and provides a good tool for further research and development towards establishment of first principles-based methods for hydrodynamic and structure design of high-speed planing craft.

Numerical modelling of structure responses for high-speed planing craft in waves

The paper presents an approach for time-domain simulation of structure responses, along with hydromechanic and structure inertia loads and motions responses, for high-speed planing craft in waves. Hydromechanic loads and motion responses are calculated with a non-linear time-domain strip method. A pressure shape function is introduced which enables formulation of detailed slamming pressure distributions sequences from the section forces in the strip method simulations. Structure responses are calculated quasi-dynamically by applying the momentary distributed pressure loads on a global finite element representation of the hull structure with use of inertia relief. From the time series output extreme responses are determined by means of short-term statistics. Promising results are demonstrated in applications on a high-speed planing craft, where extreme values of simulated structure responses are compared with responses to uniform design pressures from classification rules and measured responses from full-scale trials. The approach is concluded to be a useful tool for further research which has potential to form the basis for establishment of a computationally efficient simulation-based design methodology. A corresponding experimental modelling approach is presented in a parallel paper.

Simulation of Air\u2013Water Interface Effects for High-speed Planing Hull

High-speed planing crafts have successfully evolved through developments in the last several decades. Classical approaches such as inviscid potential flow–based methods and the empirically based Savitsky method provide general understanding for practical design. However, sometimes such analyses suffer inaccuracies since the air–water interface effects, especially in the transition phase, are not fully accounted for. Hence, understanding the behaviour at the transition speed is of fundamental importance for the designer. The fluid forces in planing hulls are dominated by phenomena such as flow separation at various discontinuities viz., knuckles, chines and transom, with resultant spray generation. In such cases, the application of potential theory at high speeds introduces limitations. This paper investigates the simulation of modelling of the pre-planing behaviour with a view to capturing the air–water interface effects, with validations through experiments to compare the drag, dynamic trim and wetted surface area. The paper also brings out the merits of gridding strategies to obtain reliable results especially with regard to spray generation due to the air–water interface effects. The verification and validation studies serve to authenticate the use of the multi-gridding strategies on the basis of comparisons with simulations using model tests. It emerges from the study that overset/chimera grids give better results compared with single unstructured hexahedral grids. Two overset methods are investigated to obtain reliable estimation of the dynamic trim and drag, and their ability to capture the spray resulting from the air–water interaction. The results demonstrate very close simulation of the actual flow kinematics at steady-speed conditions in terms of spray at the air–water interface, drag at the pre-planing and full planing range and dynamic trim angles.

Dynamic response modeling of high-speed planing craft with enforced acceleration

An approach is investigated in this study for structural dynamic analysis of a high-speed planing hull, in which the pointwise acceleration data collected from sea trials are enforced as base excitation. The paper first performed the full boat analysis of an 11-meter high speed craft for a period of one wave impact selected from each of nine seakeeping runs. The sea trial acceleration data collected from 11 accelerometers placed close to the centerline and the keel are enforced as input, while those from 3 accelerometers placed around the pilot cabin are selected for validation. The substructure dynamic analysis of the isolated pilot cabin was then conducted and validated, in which 7 pointwise enforced accelerations are selected from the simulation output of the full boat dynamic analysis. The substructure dynamic analysis enables detailed investigation of local stress concentrations where critical equipment and personnel are located. The proposed approach can be extended to rigid-flexible body coupling analysis of a high-speed craft when it is running with large pitching and yawing motion.

On hydrodynamic analysis of stepped planing crafts

Using transverse steps is one of the adopted strategies to improve the hydrodynamic characteristics of planing crafts. In the present paper, hydrodynamic characteristics of stepped planing crafts are numerically investigated. For this purpose, we analyzed the effects of five different types of transverse steps on lift to drag ratio, resistance, trim angle and sinkage of high speed planing crafts. Contours of pressure distribution on the bottom of crafts, water volume fraction and free-surface are also presented at different hull velocities. Computed numerical results are properly validated against our conducted towing tank experimental tests.