The Experts below are selected from a list of 624 Experts worldwide ranked by ideXlab platform

Yoshiho Ikeda - One of the best experts on this subject based on the ideXlab platform.

  • a study on transverse stability loss of Planing Craft at super high forward speed
    International shipbuilding progress, 2007
    Co-Authors: Toru Katayama, Masashi Fujimoto, Yoshiho Ikeda
    Abstract:

    In this study, the mechanism of a transverse stability loss at super high forward speed is investigated. Towing tank test is carried out to observe the characteristics of the instability and it is confirmed that the instability has strong relationship to the change in running attitude and hydrodynamic roll moment due to high forward speed. Using some existing empirical formulas to estimate the dynamic normal force (lift) on a Planing surface, an estimation method of inception of the unstable phenomenon is proposed and its validity is confirmed through comparing with measured results.

  • developement of resistance test for high speed Planing Craft using very small model scale effects on drag force
    2002
    Co-Authors: Toru Katayama, Shigeru Hayashita, Kouji Suzuki, Yoshiho Ikeda
    Abstract:

    In order to develop a resistance test method for high speed Planing Craft using a very small model, the scale effects on wetted surface area, frictional resistance and pressure forces acting on a small model are experimentally investigated using geosim prismatic Planing surface models. Froude number and Renolds number covered in the experiments are Fn=1.0 to 4.0 and Rn=5×10 5 to 3×10 6 , respectively. Through the analysis of resistance components, it is found that a resistance component created by removal of hydrostatic pressure on the transom due to high-speed, called transom pressure resistance in the paper, plays an important role in the resistance of a Planing Craft. The wetted surface area is confirmed to slightly decrease for a very small model at large trim angle, and to cause the reduction of the pressure force acting on the hull. The frictional resistance acting on a very small model can be predicted on the basis of the equivalent flat plate concept if appropriate prediction formulas, in which laminar and transient flow effects are taken into account, are used.

  • an experimental method to evaluate resistance and attitudes of Planing Craft using very small models
    Journal of the Society of Naval Architects of Japan, 2002
    Co-Authors: Shigeru Hayashita, Toru Katayama, Yoshiho Ikeda, Kouji Suzuki
    Abstract:

    In order to establish an experimental method to evaluate resistance and running attitudes of Planing Craft using a very small-scale model, the scale effects on hydrodynamic forces (drag, lift and trim moment) acting on two model ships, a 0.45m model and a 0.9m model, are experimentally investigated by fully captured towing tests. The results demonstrate that the lift and the moment acting on the smaller model are smaller than those on the larger model. The predicted results of running attitudes using the modified hydrodynamic forces obtained for the smaller model, in which the scale effects on the lift and the moment are taken in to account, are in fairly good agreement with the measured running attitudes of the larger model. The residual resistances predicted for the two models based on Froude's hypothesis using Blasius and Plandtl-Schlichting formulae in the prediction of frictional resistance are in fairly good agreement with each other.

  • roll damping prediction method for a high speed Planing Craft
    2000
    Co-Authors: Yoshiho Ikeda, Toru Katayama
    Abstract:

    The measured roll damping of high-speed Planing Craft by forced oscillation experiments demonstrate that the predicted damping by an existing method significantly underestimate the experimental ones. This may be because the effect of the vertical lift force acting on the Craft on the damping is not taken into account in the prediction method. Methods to predict the contributions of the vertical lift force to the roll damping are deduced on basis of a quasi-static assumption. Using the measured lift coefficient of a Craft running in steady speed which depends on trim and rise of it, the roll damping can be approximately predicted by the present method. It is confirmed that the predicted results are in fairly good agreement with the measured ones. A prediction method of heave damping of Planing Craft is also deduced on basis of same assumption.

  • a study on unstable motions of a Planing Craft in maneuvering
    Journal of the Society of Naval Architects of Japan, 2000
    Co-Authors: Toru Katayama, Yoshiho Ikeda, Hideaki Okumura
    Abstract:

    A model test method, a partly captured PMM test, to measure unstable motions of a Planing Craft induced by periodic maneuvering motion is developed. The experimental results of a Planing Craft at Fn=2.0 by the method demonstrates that a violent motion which is large rolling, heaving and pitching coupling motion occurs when the frequency of motion given by PMM coincides with the rolling natural frequency, and with the half of the heaving and pitching natural frequency of the Craft. It should be noted that the rolling motion has the same frequency as the forced motion given by PMM, but that the heaving and pitching motions have the twice of the frequency of the forced motion.In order to clarify the cause of the violent motion, the hydrodynamic forces acting on the hull in periodic maneuvering motions are measured by PMM tests for a captured model and obliquely towing tests. The experimental results show that the rolling displacement of the Craft generates hydrodynamic heaving force and pitching moment at high speed. A non-linear time-domain simulation of the motions using the measured hydrodynamic forces is carried out. The simulated motions are in fairly good agreement with the experimental ones.

Toru Katayama - One of the best experts on this subject based on the ideXlab platform.

  • an experimental study on instability of a super high speed Planing Craft with outboard engine at straight running
    2011
    Co-Authors: Toru Katayama, Kazuya Habara
    Abstract:

    Recently, there are super high-speed Planing Craft, which can run at more than 100 km/h, owing to engine improvements and reductions in hull weight. At high-speed range, where most of hull is above the water surface, even if it runs in calm water, there are some kinds of peculiar unstable phenomena. For example, porpoising, corkscrew, transverse pure stability loss, directional instability, dutchroll, and so on. In this study, the stability of a Craft with lower-hull of an outboard engine, whose real Craft causes unstable phenomena at super-high forward speed regions, is investigated experimentally. Especially, the effects of lower-hull on the stability are focused. First, in order to investigate the roll stability, the measurement of roll restoring moment is carried out. The results show that there is rarely the possibility of occurrence of the instability except for the special running attitude caused by special loading condition, etc. Second, in order to investigate maneuverability, the measurements of maneuvering hydrodynamic forces are carried out and the indexes of maneuverability are obtained. The results show that straight line stability increases but yaw checking ability decreases by attaching lower-hull of outboard engine and there is the possibility of occurrence of directional instability. Finally, in order to investigate stability of straight running based on sway-roll-yaw coupling motion, the hydrodynamic forces of the motion equation are measured. As the results of investigation by Routh–Hurwitz stability criterion, for a hull with lower-hull, it is indicated that there is the possibility of roll-yaw coupling self-excitation motion if roll and yaw damping moments are small enough.

  • a study on transverse stability loss of Planing Craft at super high forward speed
    International shipbuilding progress, 2007
    Co-Authors: Toru Katayama, Masashi Fujimoto, Yoshiho Ikeda
    Abstract:

    In this study, the mechanism of a transverse stability loss at super high forward speed is investigated. Towing tank test is carried out to observe the characteristics of the instability and it is confirmed that the instability has strong relationship to the change in running attitude and hydrodynamic roll moment due to high forward speed. Using some existing empirical formulas to estimate the dynamic normal force (lift) on a Planing surface, an estimation method of inception of the unstable phenomenon is proposed and its validity is confirmed through comparing with measured results.

  • developement of resistance test for high speed Planing Craft using very small model scale effects on drag force
    2002
    Co-Authors: Toru Katayama, Shigeru Hayashita, Kouji Suzuki, Yoshiho Ikeda
    Abstract:

    In order to develop a resistance test method for high speed Planing Craft using a very small model, the scale effects on wetted surface area, frictional resistance and pressure forces acting on a small model are experimentally investigated using geosim prismatic Planing surface models. Froude number and Renolds number covered in the experiments are Fn=1.0 to 4.0 and Rn=5×10 5 to 3×10 6 , respectively. Through the analysis of resistance components, it is found that a resistance component created by removal of hydrostatic pressure on the transom due to high-speed, called transom pressure resistance in the paper, plays an important role in the resistance of a Planing Craft. The wetted surface area is confirmed to slightly decrease for a very small model at large trim angle, and to cause the reduction of the pressure force acting on the hull. The frictional resistance acting on a very small model can be predicted on the basis of the equivalent flat plate concept if appropriate prediction formulas, in which laminar and transient flow effects are taken into account, are used.

  • an experimental method to evaluate resistance and attitudes of Planing Craft using very small models
    Journal of the Society of Naval Architects of Japan, 2002
    Co-Authors: Shigeru Hayashita, Toru Katayama, Yoshiho Ikeda, Kouji Suzuki
    Abstract:

    In order to establish an experimental method to evaluate resistance and running attitudes of Planing Craft using a very small-scale model, the scale effects on hydrodynamic forces (drag, lift and trim moment) acting on two model ships, a 0.45m model and a 0.9m model, are experimentally investigated by fully captured towing tests. The results demonstrate that the lift and the moment acting on the smaller model are smaller than those on the larger model. The predicted results of running attitudes using the modified hydrodynamic forces obtained for the smaller model, in which the scale effects on the lift and the moment are taken in to account, are in fairly good agreement with the measured running attitudes of the larger model. The residual resistances predicted for the two models based on Froude's hypothesis using Blasius and Plandtl-Schlichting formulae in the prediction of frictional resistance are in fairly good agreement with each other.

  • roll damping prediction method for a high speed Planing Craft
    2000
    Co-Authors: Yoshiho Ikeda, Toru Katayama
    Abstract:

    The measured roll damping of high-speed Planing Craft by forced oscillation experiments demonstrate that the predicted damping by an existing method significantly underestimate the experimental ones. This may be because the effect of the vertical lift force acting on the Craft on the damping is not taken into account in the prediction method. Methods to predict the contributions of the vertical lift force to the roll damping are deduced on basis of a quasi-static assumption. Using the measured lift coefficient of a Craft running in steady speed which depends on trim and rise of it, the roll damping can be approximately predicted by the present method. It is confirmed that the predicted results are in fairly good agreement with the measured ones. A prediction method of heave damping of Planing Craft is also deduced on basis of same assumption.

Anders Rosén - One of the best experts on this subject based on the ideXlab platform.

  • experimental modelling of spray deflection influence on Planing Craft performance in calm water and waves
    Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment, 2020
    Co-Authors: Anders Rosén, Chiara Wielgosz, Raju Datla, Uihoon Chung, Jonas Danielsson
    Abstract:

    This study explores the prospects of using scaled model experiments for capturing the influence of a novel spray deflection concept on Planing Craft performance in calm water and in waves. An exper ...

  • Numerical modelling of structure responses for high-speed Planing Craft in waves
    Ocean Engineering, 2020
    Co-Authors: Anders Rosén, Karl Garme, Mikael Razola, Ermina Begovic
    Abstract:

    Abstract 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.

  • high speed Craft dynamics in waves challenges and opportunities related to the current safety philosophy
    16th International Ship Stability Workshop (ISSW 2017) Belgrade Serbia 2017., 2017
    Co-Authors: Anders Rosén, Mikael Razola, Ermina Begovic, Karl Garme
    Abstract:

    This paper considers the assessment of vertical accelerations of high speed Planing Craft in waves as the principal element for the risk management approach, i.e. formulation and application of ope ...

  • on structural design of high speed Planing Craft with respect to slamming
    8th International Conference on High-Speed Marine Vehicles Mülheim an der Ruhr Germany 26-28 September 2012, 2012
    Co-Authors: Mikael Razola, Anders Rosén, Karl Garme, Ivan Stenius, Alexandros Antonatos
    Abstract:

    The development in structural design and construction of high-speed Craft has been extensive during the last decades. Environmental and economical issues have increased the need to develop more optimized structures, using new material concepts, to reduce weight and increase performance efficiency. However, both lack of, and limitations in design methodology, makes this a difficult task.In this thesis a methodological framework which enables detailed studies of the slamming loads and associated responses for high-speed Planing Craft in irregular waves is established. The slamming loads can either be formulated based on numerical simulations, or on experimental measurements and pressure distribution reconstruction. Structure responses are derived in the time-domain using finite element analysis. Statistical methods are used to determine design loads and lifetime extreme responses.The framework is applied to perform phenomenological studies of the slamming loading conditions for high-speed Craft, and used to highlight and quantify the limitations in the prevailing semi-empirical method for design load determination with respect to slamming. A number of clarifications regarding the original derivation and the applicability of the prevailing semi-empirical method are presented. Finally, several potential improvements to the method are presented and the associated implications discussed.The long-term goal of the research project is to establish a method for direct calculation of loads and response for high-speed Planing Craft, which can enable design of truly efficient Craft structures. The methodology and the results presented in this thesis are concluded to be important stepping-stones towards this goal.

  • loads and responses for Planing Craft in waves
    2004
    Co-Authors: Anders Rosén
    Abstract:

    Experimental and numerical analysis of loads and responses for Planing Craft in waves is considered. Extensive experiments have been performed on a Planing Craft, in full-scale as well as in model ...

Karl Garme - One of the best experts on this subject based on the ideXlab platform.

  • experimental modelling of local structure responses for high speed Planing Craft in waves
    Ocean Engineering, 2020
    Co-Authors: Ermina Begovic, Karl Garme, C Bertorello, A Bove, Xiangyu Lei, Jonas Persson, Giuseppe Petrone, Mikael Razola
    Abstract:

    Abstract 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
    Ocean Engineering, 2020
    Co-Authors: Anders Rosén, Karl Garme, Mikael Razola, Ermina Begovic
    Abstract:

    Abstract 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.

  • high speed Craft dynamics in waves challenges and opportunities related to the current safety philosophy
    16th International Ship Stability Workshop (ISSW 2017) Belgrade Serbia 2017., 2017
    Co-Authors: Anders Rosén, Mikael Razola, Ermina Begovic, Karl Garme
    Abstract:

    This paper considers the assessment of vertical accelerations of high speed Planing Craft in waves as the principal element for the risk management approach, i.e. formulation and application of ope ...

  • on structural design of high speed Planing Craft with respect to slamming
    8th International Conference on High-Speed Marine Vehicles Mülheim an der Ruhr Germany 26-28 September 2012, 2012
    Co-Authors: Mikael Razola, Anders Rosén, Karl Garme, Ivan Stenius, Alexandros Antonatos
    Abstract:

    The development in structural design and construction of high-speed Craft has been extensive during the last decades. Environmental and economical issues have increased the need to develop more optimized structures, using new material concepts, to reduce weight and increase performance efficiency. However, both lack of, and limitations in design methodology, makes this a difficult task.In this thesis a methodological framework which enables detailed studies of the slamming loads and associated responses for high-speed Planing Craft in irregular waves is established. The slamming loads can either be formulated based on numerical simulations, or on experimental measurements and pressure distribution reconstruction. Structure responses are derived in the time-domain using finite element analysis. Statistical methods are used to determine design loads and lifetime extreme responses.The framework is applied to perform phenomenological studies of the slamming loading conditions for high-speed Craft, and used to highlight and quantify the limitations in the prevailing semi-empirical method for design load determination with respect to slamming. A number of clarifications regarding the original derivation and the applicability of the prevailing semi-empirical method are presented. Finally, several potential improvements to the method are presented and the associated implications discussed.The long-term goal of the research project is to establish a method for direct calculation of loads and response for high-speed Planing Craft, which can enable design of truly efficient Craft structures. The methodology and the results presented in this thesis are concluded to be important stepping-stones towards this goal.

  • model experiment addressing the impact pressure distribution on Planing Craft in waves
    The International Journal of Small Craft Technology, 2004
    Co-Authors: Anders Rosén, Karl Garme
    Abstract:

    The aim of the experiment was time-domain monitoring and analysis of the pressure distribution on Planing Craft inwaves. A model was instrumented with pressure transducers and towed in calm water, ...

Songlin Yang - One of the best experts on this subject based on the ideXlab platform.

  • one optimization method on the navigation performance reliability of Planing Craft
    Pacific Rim International Symposium on Dependable Computing, 2011
    Co-Authors: Songlin Yang, Feng Zhu
    Abstract:

    In this paper, a comprehensive optimization mathematical model of the Planing Craft navigational performance reliability was established. A hierarchical parallel chaos-genetic algorithm, which is called P-CX-GA, is proposed based on parallel thinking, genetic algorithm and new chaos algorithm. The conclusion based on quantities of computation results shows that P-CX-GA is reliable and efficient. It proposed a solid foundation for hull form optimization design and evaluation analysis of the high-speed ships.

  • an experimental study on hydrodynamic characteristics of gliding hydrofoil Craft
    Journal of Marine Science and Technology, 2011
    Co-Authors: Shuling Chen, Songlin Yang
    Abstract:

    The Gliding-Hydrofoil Craft (GHC) has been recently proposed by the authors from JUST, which is partially similar to a Planing Craft but has a hydrofoil installed in the front part of the ship. To study its hydrodynamic characteristics, model tests are carried out in a towing tank, and the total resistance, trim angle and wetted area of the Craft in the cases with different Froude numbers are measured. This paper presents analysis on the experimental data and discusses the effects of the submerged depth and initial attack angle of the hydrofoil.