• Title/Summary/Keyword: Yaw Moment

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Syudy on the dynamic Stability of Ground Armored Moving Vehicle during cruising river (지상 전투차량의 수상 추진 시 동적 안정성에 대한 연구)

  • Ahn, Tai-Sul;Lee, Kyung-Hoon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.252-255
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    • 2008
  • In this study, the characteristics of crossing a river of Ground Armored Vehicle (GAV) were evaluated by numerical method and real size tests. 3-D hybrid mesh systems were constructed by 3-D models of the GAV, and a commercial software, FLUENT, was used in numerical analysis. In order to deal with multi-phase problem (air and water), Volume Of Fluid (VOF) method was used, and Moving and Deforming Mesh (MDM) was adapted for unsteady motion of GAV. There were two steps in this research. Firstly, stability of the GAV which cruised a river was evaluated by changing several shapes of water-proof-front-wing of the GAV in steady state, and compared results (free surface shape and drag value in 10km/h) with those of real size tests. Secondly, results of unsteady analysis considering weight and moment of inertia of the GAV were presented. There were showed a maximum velocity with a designed water jet and dynamic stability including pitch, roll, and yaw moment. Based on these results, the optimal shape of water-proof-front-wing of the GAV was determined for a proto-type of the GAV.

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Wave Exciting Forces Acting on Ships in Following Seas (추파중(追波中)에서 항행(航行)하는 선체(船體)에 작용(作用)하는 파강제력(波强制力)에 관(關)한 연구(硏究))

  • Kyoung-Ho,Son;Jin-Ahn,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.21 no.3
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    • pp.27-34
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    • 1984
  • When a ship is travelling in following seas, the encounter frequency is reduced to be very low. In that case broaching phenomenon is most likely to occur, and it may be due to wave exciting forces acting on ships. It is thought that the wave exciting forces acting on ships in following seas almost consist of two components. One is hydrostatic force due to Froude-Krylov hypothesis, and the other is hydrodynamic lift force due to orbital motion of water particles below the wave surface. In the present paper, the emphasis is laid upon wave exciting sway force, yaw moment and roll moment acting on ships in following seas. The authers take the case that the component of ship speed in the direction of wave propagation is equal to the wave celerity, i.e., the encounter frequency is zero. Hydrostatic force components are calculated by line integral method on Lewis form plane, and hydrodynamic lift components are calculated by lifting surface theory. Furthermore captive model tests are carried out in regular following waves generated by means of a wave making board. Through the comparison between calculated and measured values, it is confirmed that the wave exciting forces acting on ships in following seas can be predicted in terms of present method to a certain extent.

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Numerical prediction analysis of propeller exciting force for hull-propeller-rudder system in oblique flow

  • Sun, Shuai;Li, Liang;Wang, Chao;Zhang, Hongyu
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.1
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    • pp.69-84
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    • 2018
  • In order to analyze the characteristics of propeller exciting force, the hybrid grid is adopted and the numerical prediction of KCS ship model is performed for hull-propeller-rudder system by Reynolds-Averaged Navier Stokes (RANS) method and volume of fluid (VOF) model. Firstly, the numerical simulation of hydrodynamics for bare hull at oblique state is carried out. The results show that with the increasing of the drift angle, the coefficients of resistance, side force and yaw moment are constantly increasing, and the bigger the drift angle, the worse the overall uniformity of propeller disk. Then, propeller bearing force for hull-propeller-rudder system in oblique flow is calculated. It is found that the propeller thrust and torque fluctuation coefficient peak in drift angle are greater than that in straight line navigation, and the negative drift angle is greater than the positive. The fluctuation peak variation law of coefficient of side force and bending moment are different due to various causes.

Development of Ship Dynamics Model by Free-Running Model Tests and Regression (자유항주모형시험과 회귀분석을 통한 선체 동역학 모델의 개발)

  • Kim, Kiwon;Kim, Hoyong;Choi, Sungeun;Na, Ki-In;Lee, Hyuk;Seo, Jeonghwa
    • Journal of the Society of Naval Architects of Korea
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    • v.59 no.3
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    • pp.173-182
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    • 2022
  • The present study suggests a procedure of establishing a ship dynamics modeling by regression of free-running model test results. The hydrodynamic force and moment of the whole model ship is derived from the low-pass filtered acceleration in the turning circle and zigzag maneuver tests. Force and moment of the propeller and rudder are separated from that of the whole ship to acquire the hull force and moment terms, based on the principles of the component model. The low-pass filter frequency is verified in prior to dynamics modeling, to find the threshold frequency of 2.5 Hz. The dynamics modeling of the hull is compared with the component modeling by captive model tests. Because of strong correlation between sway velocity, yaw angular velocity, and heel angle, each maneuvering coefficient is not able to be validated, but the whole modeling shows good agreement with the captive model tests.

Study on Triaxiality Velocity of COMS induced by Wheel Off-loading

  • Park, Young-Woong;Kim, Dae-Kwan;Lee, Hoon-Hee
    • Bulletin of the Korean Space Science Society
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    • 2008.10a
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    • pp.36.3-36.3
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    • 2008
  • KARI (Korea Aerospace Research Institute) is going to launch a Communication, Ocean and Meteorological Satellite (COMS) at summer of 2009. It will be first thing to be developed for a geostationary satellite through domestic technology. Of course, KARI has performed this development program with EADS Astrium in France since 2005. COMS has the non-symmetric configuration that the solar array is only attached on the south panel. Due to the configuration, momentum of satellite will be rapidly accumulated induced by solar pressure and then 3 wheels of large momentum are located on roll-yaw plane for attitude control. Therefore, to prevent the saturation of wheel momentum, wheel off-loading will be performed two times per day during 10 minutes for each one. At the moment, translation movement on 3-axes direction appears because of using thrusters. In this paper, strategy of the wheel off-loading and triaxiality which is the translation effect on 3-axes are introduced. Consequently, the result of optimized triaxiality considering the wheel off-loading strategy is summarized.

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Integrated Chassis Control with Electronic Stability Control and Active Front Steering under Saturation of Front Lateral Tire Forces (전륜 횡력의 포화를 고려한 ESC와 AFS의 통합 섀시 제어)

  • Yim, Seongjin
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.10
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    • pp.903-909
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    • 2015
  • This article presents an integrated chassis control with electronic stability control (ESC) and active front steering (AFS) under saturation of front lateral tire force. Regardless of the use of AFS, the front lateral tire forces can be easily saturated. Under the saturated front lateral tire force, AFS cannot be effective to generate a control yaw moment needed for the integrated chassis control. In this paper, new integrated chassis control is proposed in order to limit the use of AFS in case the front lateral tire force is saturated. Weighed pseudo-inverse control allocation (WPCA) with variable weight is adopted to adaptively use the AFS. To check the effectiveness of the proposed scheme, simulation is performed on a vehicle simulation package, CarSim. From simulation, the proposed integrated chassis control is effective for vehicle stability control under saturated front lateral tire force.

Control of Vehicle Lateral Dynamics using Sliding Mode with Time-Varying Switching Surface (시변 절환면을 갖는 슬라이딩 모드에 의한 차량의 횡방향 운동제어)

  • Lee, Chang-Ro;Yang, Hyun-Seok;Park, Young-Pil
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.458-463
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    • 2000
  • This paper presents a design of the controller for vehicle lateral dynamics using active yaw moment. Vehicle lateral motion is incorporated with directional controllability and stability. These are conflicting each other from the view of vehicle handling performance. To compromise the trade-off between these two aspects, we suggest a new control algorithm based on the sliding mode with time-varying switching surface according to the body side slip angle. The controller can deal with the nonlinear region in vehicle driving and be robust to the parameter uncertainties in the plant model. Control performance was evaluated from the simulation.

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Design of Whirl Tower Test Facility for Helicopter Rotor System (헬리콥터 로터시스템 회전시험설비의 설계)

  • Kim, Seung-Bum;Song, Keun-Woong;Choi, Hee-Ju;Kim, Eun-Jong;Park, Byung-Kwan
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1136-1141
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    • 2008
  • The helicopter rotor system generates lift, thrust, maneuvering force and moment to the helicopter with the torque and pitch control force transferred from the main rotor hub/control. And the tail rotor system generates the thrust for yaw axis control of the helicopter with the torque and pitch control force transferred from the tail rotor hub/control. Ground whirl test shall be performed to verify the compliance of requirement performance test and dynamic test of rotor blade and hub/control. This paper describes a design of whirl tower test facility for helicopter rotor system test and evaluation. Design results are summarized and compared with design requirements.

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Vehicle Stability Control for a 4WD HEV using Regenerative Braking and Electronic Brake force Distribution (회생제동과 EBD를 이용한 4WD HEV의 차량 안정성 제어)

  • Kim Donghyun;Kim Hyunsoo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.1
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    • pp.166-173
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    • 2005
  • A vehicle stability control logic for 4WD hybrid electric vehicle is proposed using the regenerative braking of the rear motor and electronic brake force distribution module. Performance of the stability control logic is evaluated for J-turn and single lane change. It is found from the simulation results that the regenerative braking at rear motor is able to provide improved stability compared with the vehicle performance without my stability control. Additional improvement can be achieved by applying the regenerative braking plus electronic brake farce distribution control. It is expected that the regenerative braking offers additional improvement of the fuel economy as well as the vehicle stability control.

Characteristic of Hydrodynamic Interaction on Tug-Barge (예부선의 유체력 간섭 특성에 관한 연구)

  • Lee, Sang-Min;Jo, Sang-Hui
    • Proceedings of KOSOMES biannual meeting
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    • 2008.05a
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    • pp.43-47
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    • 2008
  • In order to investigate the hydrodynamic interaction between the tug-barge and bank or ship which is crossing to the opposite direction, we have executed the towing simulation of tug-barge transportation. Heading of barge, yaw moment and lateral force of tug boat are obtained by this simulation. We have analyzed the characteristics of results and propose the safety towing method for tug-barge operation.

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