• Title/Summary/Keyword: 유체 충격 압력

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이중 슬롯을 이용한 충격파/난류 경계층 간섭현상의 피동제어

  • 구병수;김현섭;김희동
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2000.11a
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    • pp.36-36
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    • 2000
  • 천음속 또는 초음속 유동이 유동장의 하류에서 부여되는 압력조건에 의하여 감속되는 경우나, 유동방향의 갑작스런 변화를 요구하는 물체 혹은 벽면이 존재하는 경우에 발생한 충격파는 벽면을 따라 발생하는 층류 혹은 난류 경계층과 복잡한 상호간섭 (interaction)을 일으켜 충격파에 의한 박리 발생, 충격파 하류에 새로운 충격파 발생, 충격파가 큰 진폭으로 진동하게 되는 현상 등을 발생시킨다. 이러한 간섭현상은 고속유동이 통과하는 유체요소나 유체기기의 성능을 좌우하는 매우 중요한 유동현상으로, 유체기계의 설계 시 사전에 고려되어야 할 중요한 공학적 문제이다.(중략)

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A Numerical Analysis for Blast Pressure and Impulse from Free-Air Burst (자유공중폭발에 의한 폭발압력과 충격량에 대한 수치해석)

  • Shin, Jinwon;Lee, Kyungkoo
    • Journal of Korean Society of Steel Construction
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    • v.28 no.4
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    • pp.271-280
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    • 2016
  • The need to accurate quantification of blast pressure loading in the near field is important because the focus of security design of critical infrastructure, buildings and bridges is for near-field detonations. Incident and reflected pressures for near-field detonations are very difficult to be measured by commercially available pressure transducers due to the high pressure and temperature, which requires a verified and validated computational fluid dynamics code to reasonably predict the near-field pressures and impulses. This paper presents numerical studies to verify and validate a CFD code for calculations of incident and reflected overpressures and impulses. The near field is emphasized and recommendations for mesh sizes to optimally simulate the near-field detonation are provided.

Pressure Wave Propagation Phenomena in Water Containing Uniformly Distributed Gas Bubbles (소량의 기포를 함유한 이상유체 내에서의 압력파의 전파현상)

  • Kim, D.-H.
    • The Journal of the Acoustical Society of Korea
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    • v.8 no.1
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    • pp.23-30
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    • 1989
  • Propagation phenomena of nonlinear pressure waves in a bubbly mixture are studied. The governing equations for a bubbly mixture are derived heuristically and energy equation is incorporated with other governing equations to take thermal effects into consideration inside the bubble. This non-isothermal condition of the bubble inside is especially important when high amplitude pressure waves are treated. Keller's equation is adapted for the bubble dynamics as practical problem. Some numerical simulations are carried out for the shock tube problem using a computer program based on the above model. A comparison with experimental results of Noordzij and van Wijngaarden shows that the structure of the wave in the shock tube experiment seems to be much more significantly affected 요 the complex heat transfer phenomena inside the bubbles than by the relative translational motion between bubbles and surrounding liquid.

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Analysis of Fluid-Structure Interaction by High Velocity Impact for Liquid Filled Cylindrical Container (고속충돌에 의한 원통형 액체 용기의 유체-구조 연성해석)

  • Bae, Hongsu;Woo, Kyeongsik;Kim, In-Gul;Kim, Jong-Heon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.2
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    • pp.108-115
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    • 2016
  • In this paper, fluid-structure of interaction behavior of a fluid-filled cylindrical polymer container impacted by a high speed spherical projectile was studied using ALE(Arbitrary Lagrangian Eulerian) method. The hydrodynamic ram phenomenon occurred by the impact projectile penetrating through the container was investigated by examining time histories of projectile velocity and fluid pressure and density. The analysis results were agreed reasonably well compared to those by experiments.

Numerical Analysis on Shock Waves Influence Generated by Supersonic Jet Flow According to Working Fluids (작동유체에 따른 초음속 제트유동에 의해 생성되는 충격파 영향에 관한 수치해석)

  • Jung, Jong-Kil;Yoon, Jun-Kyu;Lim, Jong-Han
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.510-517
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    • 2016
  • Supersonic jet technology using high pressures has been popularly utilized in diverse industrial and engineering areas related to working fluids. In this study, to consider the effects of a shock wave caused by supersonic jet flow from a high pressure pipe, the SST turbulent flow model provided in the ANSYS FLUENT v.16 was applied and the flow characteristics of the pressure ratio and Mach number were analyzed in accordance with the working fluids (air, oxygen, and hydrogen). Before carrying out CFD (Computational Fluid Dynamics) analysis, it was presumed that the inlet gas temperature was 300 K and pressure ratio was 5 : 1 as the boundary conditions. The density function was derived from the ideal gas law and the viscosity function was derived from Sutherland viscosity law. The pressure ratio along the ejection distance decreased more in the lower density working fluids. In the case of the higher density working fluids, however, the Mach number was lower. This shows that the density of the working fluids has a considerable effect on the shock wave. Therefore, the reliability of the analysis results were improved by experiments and CFD analysis showed that supersonic jet flow affects the shock wave by changing shape and diameter of the jet, pressure ratio, etc. according to working fluids.

A Study of the Influence of the Injection Location of Supersonic Sweeping Jet for the Control of Shock-Induced Separation (경사충격파 박리유동 제어를 위한 초음속 진동제트 분출위치의 영향성 연구)

  • Park, Sang-Hoon;Lee, Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.11
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    • pp.747-754
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    • 2022
  • An experimental study was carried out to control a shock-induced boundary layer separation by utilizing the supersonic sweeping jet from the fluidic oscillator. High-speed schlieren, surface flow visualization, wall pressure measurement and precise Pitot tube measurement were applied to observe the influences of the location and the supply pressure of the fluidic oscillator on the characteristics of the oblique-shock-induced boundary layer separation. The characteristics of the separation control by the present supersonic fluidic oscillator was quantitatively analyzed by comparing with a conventional control method utilizing an air-jet vortex generator.

Heat and Flow Characteristics on the High Speed Bullet Penetrated a Fuel Tank (고속 충격탄의 연료탱크 관통 시 내부 열유동해석)

  • Lee, Seung-Chul;Park, Young-Rock;Lee, Hae-Pyeong;Park, Young-Ju
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2010.10a
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    • pp.324-327
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    • 2010
  • 본 연구에서는 차량 연료탱크에 충격탄 관통 시 화재발생 여부를 분석하기 위한 연구의 전단계로서, 충격탄 속도 변화에 따른 연료탱크 내부의 유동특성을 분석하기 위해 전산유체역학기법을 도입하여 수치해석을 수행한 결과, 충격탄이 연료탱크 관통 시작부터 $3.33{\times}10^{-6}ms$$145.01{\times}10^{-6}ms$ 경과 후, 최대속도는 각각 약 249.8m/s와 189.2m/s이며 최대 압력은 83.6kPa과 37.9kPa이다. 충격탄이 관통부로 유입되면서 급격한 압력변화가 발생함을 알 수 있었다.

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Characteristics of Piezoelectric Sensor for Fluid Impact Pressure (유체 충격 압력 측정용 압전 센서 특징)

  • Choi, Young-Myung;Kim, Hyun-Yi;Park, Jun-Soo;Kwon, Sun-Hong;Kim, Dong-Jean
    • Journal of Ocean Engineering and Technology
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    • v.23 no.6
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    • pp.17-22
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    • 2009
  • This study presents an investigation of the characteristics of piezoelectric sensors whose main utilization is to measure impact pressure. The piezoelectric sensors were tested from several points of view. Their characteristics were investigated for repeatability, the effect of the diameter, temperature effect, water purity, flush mounting, and AC and DC coupling. Out of these, it was revealed that the temperature effect is very significant. The characteristics of the AC and DC coupling are also very important in understanding the time history of the impact pressure.

A Numerical Study on the Prediction of Sloshing Impact Pressure (Sloshing 충격압력의 추정을 위한 수치기법에 관한 연구)

  • Y.H. Kim;Y.J. Park;H.R. Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.30 no.4
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    • pp.61-73
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    • 1993
  • In the present study, sloshing problem is analyzed by the application of Finite Difference Method. SOLA-SURF scheme is applied to the analysis of fluid motion considering free surface. Especially, the concept of impact buffer zone is introduced for the prediction of more realistic impact pressure on tank. Numerical computation is carried out for the typical three models, and the computed results show good agreement with experimental data. The computation is also performed for 300,000 tons VLCC as a real-ship application. From the present study, it is proved that this numerical technique is quite practical to the prediction of sloshing impact pressure.

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Fluidic Thrust Vector Control Using Shock Wave Concept (충격파 개념에 기반한 유체 추력벡터제어에 관한 연구)

  • Wu, Kexin;Kim, Heuy Dong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.4
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    • pp.10-20
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    • 2019
  • Recently, fluidic thrust vector control has become a core technique to control multifarious air vehicles, such as supersonic aircraft and modern rockets. Fluidic thrust vector control using the shock vector concept has many advantages for achieving great vectoring performance, such as fast vectoring response, simple structure, and low weight. In this paper, computational fluid dynamics methods are used to study a three-dimensional rectangular supersonic nozzle with a slot injector. To evaluate the reliability and stability of computational methodology, the numerical results were validated with experimental data. The pressure distributions along the upper and lower nozzle walls in the symmetry plane showed an excellent match with the test results. Several numerical simulations were performed based on the shear stress transport(SST) $k-{\omega}$ turbulence model. The effect of the momentum flux ratio was investigated thoroughly, and the performance variations have been clearly illustrated.