• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.5
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• pp.712-717
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• 2013

The gas management system for a vertical launching system must be safely managed within a ship. The plenum and uptake are capable of containing and surviving a full-burning restrained firing without loss of gas management integrity. To secure the safety, the pressure characteristics with a supersonic under-expanded jet on a gas management system are numerically investigated using computational fluid dynamics. The results of present analysis and the preliminary design of the gas management system are described in this paper.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.301-305
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• 2006

The Vertical Launching System design is especially complicated by complex flow structure in a plenum with the severe thermal state and high pressure load form the hot exhaust plume. The flow structures are numerically simulated by using the commercial code, CFD-FASTRAN with the axi-symmetrical Navier-Stokes equations. Two different cases are considered; that is, the stationary fire and the moving fire.

• Journal of Ship and Ocean Technology
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• v.6 no.1
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• pp.1-15
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• 2002

A new concept for launching free-fall lifeboats, proposed by Yokohama National University is described in this paper. It has been pointed out that, using the conventional single-skid free-fall system, the potential for dangerous lifeboat motions (in which the lifeboat moves backward or jerks on the surface after entering the water) increases with the fall height of the lifeboat. One of the principal causes of this undesirable motion is vertical rotation of the lifeboat during its restricted fall at the edge of the launching skid. Thus a new "double-skid"launching concept is proposed to effectively eliminate the rotation of the lifeboat at the skid end and to enable the lifeboat to move smoothly after entering the water. In order to evaluate the performance of the proposed method, a series of model experiments and numerical simulations is carried out in which two lifeboat models with overall lengths of 1 meter and 6 meters are used. The effects of design parameters such as skid angle and skid height are investigated, and an example of the implementation of this new system at the stern of a large merchant ship is illustrated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.9
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• pp.889-895
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• 2012

A vertical launching system(VLS) is a system for holding and firing missiles on surface ships. When a missile is launched in VLS, relative motion between canister and missile and drag force induced by wind can cause initial unstability of a missile. Thus dynamic analysis of initial behavior of vertically launched missile should be performed to prevent collision with any structure of a ship. In this study, dynamic analyses of initial behavior of vertically launched missile are performed using Monte-Carlo simulation, which relys on random sampling and probabilistic distribution of variables. Each parameter related with dynamic behavior of a missile is modeled with probability variables and Recurdyn, a commercial software for multi body dynamic analysis, is used to perform Monte-Carlo simulation. As a result, initial behavior of a missile is evaluated with respect to various performance indexes in a probabilistic sense and sensitivity of the each parameters is calculated.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.143-143
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• 2003

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.664-671
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• 2017

This paper presents a numerical analysis of behaviors of rear closer of vertical launch system under rocket plume based on fluid structure interaction analysis. The rocket plume loading is modeled by fully Eulerian method and elasto-plastic behavior of rear cover is calculated by total Lagrangian method based on a 9-node planar element. The interface motion and boundary conditions are described by a hybrid particle level-set method within the ghost fluid framework. We compare the fluid flow pattern between different rear closer models which are elast-plastic and rigid deformation.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.2
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• pp.67-75
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• 2002

In the course of missile system design, jet plume impingement is encountered in designing airframe as well as launchers, requiring careful investigation of its effect on the system. In the present paper, recent works on such topic are presented to demonstrate usefulness of CFD results in helping design the hardware. The jet impinging flow structure exhibits such complex nature as shock shell, plate shock and Mach disk depending on the flow parameters. The main parameters are the ratio of the jet pressure to the ambient pressure and the distance between the nozzle and the wall. In the current application, the nozzle contour and the pressure ratio are held fixed, but the jet impinging distance is varied to illuminate the characteristics of the jet plume with the distance. The same methodology is then applied to a complex vertical launcher system (VLS), capturing its flow structure and major design parameter. These applications involving jets are thus hoped to demonstrate the usefulness and value of CFD in designing a complex structure in the real engineering environment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.3
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• pp.218-225
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• 2013

Vertically-launched missiles are supported as erected vertically in the vertical launching system of warship, and they should be mounted in the same way when vibration-tested. However, mounting missiles vertically makes a fixture, which is a supporting structure, bulky and heavy so requiring a high-performance exciter. Mounting missiles as laid down horizontally in a vibration test is economical regarding fixture manufacturing and exciter performance, but it makes test results incorrect because the different mounting direction has effects on the test results. A bending moment due to missiles' weight happens to missiles, and resilient mounts, which support missiles in the vertical launch system, deflect differently from the real situation because of the static deflection of these mounts due to missiles' weight. If the resilient mounts supporting missiles have nonlinear force-deflection characteristics, vibration test results become more different from the true results. This paper proposes to support missiles with an additional resilient mount such as a bunge code in order to solve those problems coming from mounting vertically-launched missiles as laid down horizontally in vibration tests. The proposed approach enables to obtain the same test results as in their actual mounting condition even though vertically-launched missiles are mounted in a different direction.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.4
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• pp.708-715
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• 2010

In Strapdown Inertial Navigation System, alignment accuracy is the most important factor to determine the performance of navigation. However by an existing self-alignment method, it takes a long time to acquire the alignment accuracy that we want. So, to attain the desired alignment accuracy in as little as $\bigcirc$ minutes, we have developed the precise multi-position alignment method. In this paper, it is proposed a inertial measurement matching transfer alignment method among alignment methods to minimize the alignment error in a short time. It is based on a mixed velocity-DCM matching method be suitable to the operating environment of vertical launching system. The compensation methods to reduce misalign error, especially azimuth angle error incurred by measurement time-delay error and body flexure error are analyzed and evaluated with simulation. This simulation results are finally confirmed by experimentations using FMS(Flight Motion Simulator) in Lab and the integration test to follow the fire control mission.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1631-1636
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• 2004

The supersonic impinging jet has been extensively applied to rocket launching system, gas jet cutting control, gas turbine blade cooling, etc. In such applications, wall temperature of an object on which supersonic jet impinges is a very important factor to determine the performance and life of the device. However, wall temperature data of supersonic impinging jets are not enough to data. The present study describes an experimental work to measure the wall temperatures of a vertical flat plate on which supersonic, dual, coaxial jet impinges. An Infrared camera is employed to measure the wall temperature distribution on the impinging plate. The pressure ratio of the jet is varied to obtain the supersonic jets in the range of over-expanded to moderately under-expanded conditions at the exit of coaxial nozzle. The distance between the coaxial nozzle and the flat plate was also varied. The coaxial jet flows are visualized using a Shadow optical method. The results show that the wall temperature distribution of the impinging plate is strongly dependent on the jet pressure ratio and the distance between the nozzle and plate.