• Title/Summary/Keyword: propulsive

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Nonlinear Adaptive Velocity Controller Design for an Air-breathing Supersonic Engine

  • Park, Jung-Woo;Park, Ik-Soo;Tahk, Min-Jea
    • International Journal of Aeronautical and Space Sciences
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    • v.13 no.3
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    • pp.361-368
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    • 2012
  • This paper presents an approach on the design of a nonlinear controller to track a reference velocity for an air-breathing supersonic vehicle. The nonlinear control scheme involves an adaptation of propulsive and aerodynamic characteristics in the equations of motion. In this paper, the coefficients of given thrust and drag functions are estimated and they are used to approximate the equations of motion under varying flight conditions. The form of the function of propulsive thrust is extracted from a thrust database which is given by preliminary engine input/output performance analysis. The aerodynamic drag is approximated as a function of angle of attack and fin deflection. The nonlinear controller, designed by using the approximated nonlinear control model equations, provides engine fuel supply command to follow the desired velocity varying with time. On the other hand, the stabilization of altitude, separated from the velocity control scheme, is done by a classical altitude hold autopilot design. Finally, several simulations are performed in order to demonstrate the relevance of the controller design regarding the vehicle.

The Evaluation of Ship's Cruising Ability and Propulsive Performance in a Seaway (선박의 풍파중 항해능력 및 추진성능 평가에 관한 연구)

  • 김순갑
    • Journal of the Korean Institute of Navigation
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    • v.14 no.2
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    • pp.15-31
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    • 1990
  • Recently, there is a tendency to design the large full ships with lower-powered engine as the means for energy saving in ship's navigation at seas. Such a lower-powered ship is anticipated to show the different propulsive performance in rough seas, because the fluctuation of main engine load of lower powered ship is relatively large as compared with higher-powered ship is relatively large as compared with higher-powered ship. The fluctuation of propeller load is nonlinear at racing condition in waves. It is due to the variation of inflow velocity into propeller, the propeller immersion and the characteristics of engine governor. In this paper, the theoretical calculation of the nominal speed loss and the numerical simulation for the nonlinear load fluctuation of a model ship in rough seas are carried out. From the results of calculation, the following are discussed. (1) The ratio of nominal speed loss to the speed in still water. (2) The manoeuvring ability of ship and the operational ability of main engine in a seaway. (3) A method of the evaluation for the fluctuation of propeller torque and revolution on the engine characteristics plane. (4) The effect of engine governor characteristics on the propeller load fluctuation.

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The Ground Test and Evaluation to Verify Engine Performance of Sea-Star I (해성I의 공기흡입식 엔진 성능 검증을 위한 지상시험평가)

  • Jung, Jae-Won;Kim, Jong-Jin;Park, Sang-Woo;Kim, Sang-Yong;Kim, Moo-Gon;Kim, Tae-Hoon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.05a
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    • pp.381-384
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    • 2009
  • The Air-breathing engine like Sea-Star I is a second propulsive force generator to fly to the target after the booster generating initial propulsive force is separated. The performance of Sea-Star I engine should be verified because the cruise missile controls direction and altitude during flight, so ground engine test is executed before flight test. This these presents evaluation method of ground engine test to verify performance of Sea-Star I's engine.

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A Study on Prediction of Propulsive Energy Loss Related to Automatic Steering of Ships in Following Seas (추사피중에서 자동조타로써 항행하는 선박의 추진에너지 손실량 평가에 관한 연구)

  • 이경우;손경호
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 1996.04a
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    • pp.77-92
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    • 1996
  • When an automatic course-keeping is concerned as is quite popular in modern navigation the closed-loop steering system consists of autopilot device power unit (or telemotor unit) steering gear magnetic or gyro compass and ship dynamics. The consideration of irregular disturbances to ship dyanmics and a few non-linear mechanisms involved in the system inevitably or artificially are known to be very important in properly evaluating or analyzing the automatic steering system. In the present study the mathematical model of each element of an automatic steering system is derived which takes account of a fex non-linear mechanisms. PD(Proportional-Derivative) controller and low-pass filter with a weather adjustment are adopted to modelling the characteristics of an autopilot. The calculation method of imposing irregular disturbances to ship dynamics is proposed where irregular disturbances implying irregular wave and the fluctuating component of wind. For he evaluation of automatic steering system of ships in the open seas an important term "performance index" is introduced from the viewpoint of energy saving which derived from the concept of energy loss on ship propulsion. Finally the present methods are applied to two typical types of ship ; an ore carrier and a fishing boat. The various effects of linear and/or non-linear control constants of autopilot on propulsive energy loss are investigated to validate and clarify the present smulation technique.

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Optimization of Input Parameters by Using DOE for Dynamic Analysis of Bio-inspired Robotic Fish 'Ichthus' (생체모방형 물고기 로봇 '익투스'의 동적 해석을 위한 DOE를 이용한 입력파라미터 최적화)

  • Chung, Chang-Hyun;Lee, Sang-Hyo;Kim, Kyoung-Sik;Cha, You-Sung;Ryuh, Young-Sun
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.8
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    • pp.799-803
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    • 2010
  • Recently, there is a rising interest on studying bio-inspired robotic fish because of real fish's great maneuverability and high energy efficiency. However, the researches about the robotic fish have not been done so much and there are still lots of problems to use them in the real environment such as in the river. This paper describes a bio-inspired robotic fish 'Ichthus' which is developed in KITECH and has 3 DOF propulsive mechanism. We develop the dynamic motion equation of 'Ichthus' in the underwater environment and analyze response characteristics of 'Ichthus' according to the input parameters of tail fin's amplitude and oscillation frequency. Then we propose control parameters at the various velocities. These parameters are useful to increase energy efficiency and it can be used when the fish robot moves in the real environment, for example, we can propose proper amplitude and oscillation frequency when the fish robot passes through the narrow space between obstacles.

Comparison of Waterjet Performance for Tracked Vehicle according to the Variation of Impeller Diameter (궤도 차량용 물 분사 추진 장치의 임펠러 직경 변화에 따른 성능 비교)

  • Kim, Hyun-Yul;Kim, Moon-Chan;Chun, Ho-Hwan
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.5
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    • pp.21-27
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    • 2004
  • A waterjet propulsion system has many advantages compared with a conventional screw propeller especially for amphibious military vehicles because of a good maneuverability at low speed, good operating ability at shallow water, high thrust at low speed to aid maneuverability and exit from water, etc. Especially, compact design is important for the tracked-vehicle because of buoyancy in water and available space inside the tracked vehicle. The experiment is parametrically performed for various impeller diameters for more compact design. The experimental results are analyzed according to the ITTC 1996 standard analysis method as well as the conventional propulsive factor analysis method. The full-scale effective and delivered power of the tracked-vehicle are evaluated according to the variation of impeller diameter. This paper emphasized the effect of impeller diameter on the performance of waterjet system.

A Study on Residual Stress Analysis of Autofrettaged Thick-walled Cylinders (자긴가공된 후육실린더의 잔류응력 해석에 관한 연구)

  • Kim, Jae-Hoon;Shim, Woo-Sung;Lee, Young-Shin;Cha, Ki-Up;Hong, Suck-Kyun
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.12
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    • pp.110-116
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    • 2009
  • Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. However, the Bauschinger effect reduces the compressive residual stresses as a result of prior tensile plastic strain, and decreases the beneficial autofrettage effect. The purpose of the present paper is to predict the accurate residual stress of SNCM8 high strength steel using the Kendall model which was adopted by ASME Code. The uniaxial Bauschinger effect test was performed to decide BEF, then this constant was used in calculation. There were some differences between theoretical solution and modified solution.

A note on "An Experimental Study on the Propulsive Characteristics of Sculls" ("선미 노의 추력발생기구 규명을 위 실험적 연구"에 관한 노트)

  • 사쿠라이다케오
    • Bulletin of the Society of Naval Architects of Korea
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    • v.38 no.3
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    • pp.88-92
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    • 2001
  • H. Kim, B.K. Lee and C.K. Rheem have been experimentally studied to clarified the mechanism of thrust force generated by sculling motion for the propulsion of Korean small boats. The experimental investigations have been conducted under the bollard condition by installing a scull at the end of a trimming tank of towing tank. The sculling motion produced by the skilful fisherman and the resultant venerated forces have been measured in respect to the Cartesian coordinate fitted to the pivot point of the scull. ("An Experimental Study on the Propulsive Characteristics of Sculls". J. of the Soc. of Naval Arch. of Korea, Vol. 26, No. 3, 1989, pp.13-24) Through these experiments the trajectory of the blade tip and the angular displacement of the blade section have been measured as shown in Fig. 1 and 2 of this paper. And at the same time the resultant hydrodynamic force components are expressed in Fig. 3 and 4. These three dimensional data of sculling motion and generated real time force components are the unique experimental information which could clarify the thrust force generating mechanism of sculling motion. The experimental results have been reanalyzed by focusing the relation between instantaneous attack angle of blade section and the resultants real time force components. Through these investigation it is found out that the conventional imagination that the 7cull motion should be effective in generating lift force must be reconsidered because the attack angle of scull blade are too great to free from stall phenomena during the sculling operation.

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A Numerical Study for Improvement of the Speed-performance of a Ship with Flow Control Flat Plate (유동제어평판을 가진 선박의 속도성능 향상에 관한 수치적 연구)

  • Park, Dong-Woo;Choi, Hee-Jong;Yoon, Hyun-Sik;Chun, Ho-Hwan
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.3
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    • pp.268-278
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    • 2009
  • The present study focused on evaluation for the performance of the Flow Control Flat Plate (FCFP) attached in the stern side of the ship. The important function of this FCFP is to enhance the resistance performance through the decrease of stern sinkage and the propulsive performance by the adjustment of inflow velocities in the propeller plane. Two different hull forms were considered to identify the effects of the FCFP. The attachment position, the angle and the size of the FCFP were studied in this numerical simulation. In this paper, the roles of the FCFP were intended to analyze fully through the numerical interpretation.

Simulation for the Propulsion of Micro-Hydro-Machine with Unstructured Grid (비정규 격자를 이용한 극소 로봇의 추진 해석)

  • Moon-Chan Kim;Dong-Dai Ha
    • Journal of the Society of Naval Architects of Korea
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    • v.39 no.3
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    • pp.1-7
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    • 2002
  • Flow mechanism of contractive and dilative motion is numerically investigated to obtain a propulsive force in highly viscous fluid, which is the simulation of the propulsion in micro-organisms. The computing code for the analysis of complicated motions is developed with cell-centered unstructured grid scheme. The developed code is validated by the well-known problems of cavity flow and oscillating wall. The validated code is applied to the contractive and dilative motion in narrow tube. The computed results are compared with nodal points scheme. By the present results, it is found that propulsive force can be obtained by the contractive and dilative motion through simulation with the developed code.