• Title/Summary/Keyword: Ogive

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RCS Reduction of Generic Missile from Elliptical Ogive Head (타원형 Ogive헤드에 의한 미사일 구조의 RCS감소)

  • 심재륜;한대현
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.4
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    • pp.901-905
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    • 2000
  • An elliptical ogive head for a generic missile is proposed to reduce its detectable probability from aground defense radar. Numerical RCS results of a generic missile with an elliptical ogive head are evaluated using the GTD/UTD (Geometrical Theory of Diffraction/uniform GTD). The results are compared with those of a cylindrical ogive head. In the sense of aerodynamics, the performance evaluation of an elliptical ogive head for a generic missile should be followed.

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Low RCS Characteristics of an Elliptical Ogive Head (타원형 Ogive 형상을 가지는 헤드의 Low RCS 특성)

  • 심재륜;한대현;김효태
    • Proceedings of the IEEK Conference
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    • 2000.06a
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    • pp.263-266
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    • 2000
  • An elliptical ogive head for a generic missile is proposed to reduce its detectable probability from a ground defense radar. Numerical RCS results of a generic missile with an elliptical ogive head are evaluated using the GTD/UTD (Geometrical Theory of Diffraction/Uniform GTD). The results are compared with those of a cylindrical ogive head. In the sense of aerodynamics, the Performance evaluation of an elliptical ogive head for a generic missile should be followed.

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A COMPUTATIONAL STUDY ON THE CHARACTERISTICS OF ASYMMETRIC VORTEX OF TANGENT-OGIVE-CYLINDER FLIGHT VEHICLE AT HIGH ANGLES OF ATTACK (Tangent-Ogive-Cylinder 비행체의 고앙각에서의 비대칭 와류 특성 연구)

  • Lim, S.;Kim, S.D.;Song, D.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.04a
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    • pp.3-7
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    • 2007
  • The characteristics of asymmetric vortex and side force of tangent-ogive-cylinder flight vehicle at high angles of attack have been performed by using upwind Navier-Stokes method with the ${\kappa}-{\omega}$ turbulence model. And Asymmetric transition positions are considered for generation of asymmetric vortex.

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Experimental Study for the Aerodynamic Characteristics of Slanted-Base Ogive Cylinder (기저면이 경사진 Ogive실린더의 공력특성에 관한 실험적 연구)

  • 맹주성;양시영;오세진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.10
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    • pp.2664-2674
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    • 1994
  • Drag, lift, and pitching moment measurements have been made on a range of slanted-base ogive cylinders, using the KANOMAX wind tunnel and balance system. Test Reynolds numbers(based on model maximum diameter) varied from $0.54{\times}10^{5}{\;}to{\;}1.56{\times}10^{5}$. Crossflow velocity maesurement was conducted by 5-hole pitot tube at $Re_{D}=1.46{\times}10^{5}$. For two base angle $({\theta}=30$ and 45 deg.), aerodynamic forces and moment were measured with increasing angle of attack(0~30 deg.). Two types of wake flow were observed, a quasisymetric turbulent closure or a longitudinal vortex flow. Aerodynamic characteristics differ dramatically between the two wake types. It was found that the drag, lift and pitching moment coefficients increased with increasing angle of attack.

NUMERICAL ANALYSIS OF CAVITATION FLOW AROUND OGIVE-CYLINDER AND VENTURI (Ogive-Cylinder 주위와 Venturi에서의 캐비테이션 전산 유동해석)

  • Lee, J.C.;Ahn, B.K.;Kim, D.H.;Kim, C.K.;Park, W.G.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.04a
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    • pp.130-133
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    • 2007
  • A two-phase method in CFD has been developed and is applied to model the cavitation flow. The governing equation system is two-phase Navier-Stokes equation, comprised of the mixture mass, momentum and liquid-phase mass equation. It employs an implicite, dual time, preconditioned algorithm using finite difference scheme in curvilineal coordinates and Chien ${\kappa}-{\varepsilon}$ turbulence equation. The experimental cavitating flows around ogive-cylinder and venturi type objects are employed to test the solver. To prove the capabilities of the solver, several three-dimentional examples are presented.

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Effect of the Flow Actuator on the Asymmetric Vortex at High Angle of Attack (고받음각 오자이브의 비대칭 와류에 작용하는 구동기 효과 분석)

  • Lee, Eunseok;Lee, Jin Ik;Lee, Kwang Seop
    • Journal of the Korea Institute of Military Science and Technology
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    • v.16 no.5
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    • pp.607-612
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    • 2013
  • The effect of the flow actuator on the asymmetric vortex structure around the ogive-cylinder body with fineness ratio of 4 flying at the speed of Mach 0.1 at angle of attack of 50 degree is studied. The ogive-cylinder model is developed with the actuator placed near the nose tip and numerically simulated using the in-house CFD code named KFLOW. The numerical simulation employs two different actuator modeling: one is the boundary condition given by blowing normal to the surface and another shearing on the surface. The numerical simulation reveals that response of the vortex structure to the actuation is dependent on the type of modeling as well as the strength and direction of the actuation.

Numerical study on concrete penetration/perforation under high velocity impact by ogive-nose steel projectile

  • Islam, Md. Jahidul;Liu, Zishun;Swaddiwudhipong, Somsak
    • Computers and Concrete
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    • v.8 no.1
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    • pp.111-123
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    • 2011
  • Severe element distortion problem is observed in finite element mesh while performing numerical simulations of high velocity steel projectiles penetration/perforation of concrete targets using finite element method (FEM). This problem of element distortion in Lagrangian formulation of FEM can be resolved by using element erosion methodology. Element erosion approach is applied in the finite element program by defining failure parameters as a condition for element elimination. In this study strain parameters for both compression and tension at failure are used as failure criteria. Since no direct method exists to determine these values, a calibration approach is used to establish suitable failure strain values while performing numerical simulations of ogive-nose steel projectile penetration/perforation into concrete target. A range of erosion parameters is suggested and adopted in concrete penetration/perforation tests to validate the suggested values. Good agreement between the numerical and field data is observed.

Mechanics of missile penetration into geo-materials

  • Siddiqui, N.A.;Abbas, H.
    • Structural Engineering and Mechanics
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    • v.13 no.6
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    • pp.639-652
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    • 2002
  • The present study aims to improve an existing model for the prediction of deceleration time history, penetration depth and forces on ogive and conical nose shaped missiles under normal impact into geo-material targets. The actual ogive nose shaped missile has been considered in the analysis and the results thus obtained have been compared with the existing model and significant improvements are found. A close proximity in the results has also been observed with the experimental values. The results of ogive nose shaped missile have also been compared with equivalent conical nose shaped missile. Variation of radial stresses along nose length and radial direction has been studied. Effect of CRH on missile penetrating performance has been investigated.

A Study on the Improvement of Penetration Capability of a Shaped Charge by Controlling the Jet Mass Parameters (제트 질량 변수 조절에 의한 성형작약 관통성능 증대 연구)

  • So, Byeongkwan
    • Journal of the Korea Institute of Military Science and Technology
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    • v.18 no.5
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    • pp.566-573
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    • 2015
  • The most important factor for the penetration performance of shaped charge is the liner design. By designing the liner to have properties of both high jet tip velocity and long jet break-up time, the better penetration performance could be acquired. Usually it is very difficult to satisfy above two conditions simultaneously. In this study, the liner with the shape of ogive was developed to have relatively larger jet mass compared to the conventional trumpet liner. The designed shaped charge showed jet properties with high jet tip velocity and long jet break-up time by using ogive liner and wave shaper. A commercially available hydro-dynamic code AUTODYN-2D was used for numerical analysis of jet formation. The flash X-ray test and the static penetration test were conducted to verify the results of numerical analysis.

A Study on the Plastic Forming by Rotary Swaging Process (Rotary Swaging 공법을 적용한 탄체 소성가공에 관한 연구)

  • Shon, Byoung-Chul;Lee, Ho-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.6
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    • pp.672-678
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    • 2020
  • Ogive parts of large-caliber ammunition in Korea are manufactured by the Press Nosing method, but this method has the disadvantage of requiring additional processes such as lubrication before and after the press process. This study proposes the possibility of applying the Swaging method to improve these shortcomings. A large-diameter shell body was manufactured in sub-scale and plastic working experiments using a swaging process were performed. We investigated whether plastic processing is possible up to 75 % of the diameter reduction rate that satisfies the final molding dimension, and whether the dimensions of the product produced by swaging molding are satisfactory as the hardness changes according to the diameter reduction rate and the increase in thickness. The test using the prototype confirmed that the hardness increased proportionally with the diameter reduction rate and by more than HV 335 at the reduction rate of 75 %. The material thickness variation tended to be similar to the theoretical calculated value, and the thickness increase rate was proportional to 65.4 % at the reduction rate of 75 %.