• Title/Summary/Keyword: 벽분사

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Case Studies on Ground Improvement by High Pressure Jet Grouting(II) Effect on the Ground Reinforcement and Cut off of Ground Water Behind Temporary Retaining Walls (고압분사주입공법에 의한 지반개량사례연구(II) -흙막이벽 배면지반보강 및 차수효과)

  • Yun, Jung-Man;Hong, Won-Pyo;Jeong, Hyeong-Yong
    • Geotechnical Engineering
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    • v.12 no.5
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    • pp.5-16
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    • 1996
  • When braced excavation with temporary retaining wall installation, is performed in loose sand with high ground water level boiling may be induced and considerable damage on the excavation works and structures in the vicinity can take place. Recently, for the purpose of reinforcement of ground and cut-off of ground water behind the temporary retaining wall, high pressure jet grouting is widely used. The purpose of this paper is to investigate the effects of jet grouting on ground reinforcement and cut -off of the ground water behind temporary retaining walls for braced excavation. A series of both laboratory and field tests has been performed. The test results show that high pressure jet grouting has sufficient effects on reinforcement of stiffness of ground and retaining wall. The permeability of the improved ground was 10-f_ 10-3cm l s smaller than those of the original ground. Therefore, the effect on cut off of ground water behind temporary retaining walls could be improved by high pressure jet grouting method.

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Prediction of Temperature Field in a Channel with Wall Injection Using Dynamic Mixed Model (동적혼성모델을 이용한 벽분사가 있는 채널의 온도장 예측)

  • Na, Yang;Kim, Hak-Jong
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.604-609
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    • 2003
  • Turbulent temperature field in a channel with wall injection has been investigated using dynamic mixed model(DMM). This flow is pertinent to internal flows inside the hybrid rocket motors. In general, the results obtained with DMM are in better agreement with DNS results compared to those of dynamic Smagorinsky model(DSM). Such favorable features of DMM are attributed to the fact that it explicitly calculates the modified Leonard stress term which takes care of the local interaction between resolved and SGS stresses and only models the remaining cross and SGS Reynolds stress terms.

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Internal Flow Characteristics & Performance Analysis of Plain Orifice and Pressure Swirl Atomizers (단공 분사기와 압력 선회형 분사기의 내부유동 특성 및 성능해석)

  • Lee Jang-Woo;Hwang Yong-Seok;Sung Hong-Gye
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.93-99
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    • 2005
  • Performed were 2-phase numerical studies on two types of fuel atomizers, plain orifice and pressure swirl atomizer. In case of plain orifice, cavitation model was applied so that discharge coefficient, cavitation size, and magnitude of cavitation region characterized and compared with experimental results for several different pressure enforced to the orifice. In case of swirl atomizer, VOF model was applied to analyze air core size, spray angle, and wall pressure distributions with comparison of experimental results.

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Study of Spray Droplet/Wall Interaction (분무액적과 벽의 상호작용에 대한 연구)

  • 양희천;유홍선;정연태
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.4
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    • pp.86-100
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    • 1998
  • The impingement of the fuel spray on the wall within the combustion chamber in compact high-pressure injection engines and on the intake port wall in port-fuel-inje- ction type engines is unavoidable. It is important to understand the characteristics of impinging spray because it influences on the rate of fuel evaporation and droplet distrib- ution etc. In this study, the numerical study for the characteristics of spray/wall interaction is performed to test the applicability and reliability of spray/wall impingement models. The impingement models used are stick model, reflect model, jet model and Watkins and Park's model. The head of wall-jet eminating radilly outward from the spray impingement site contains a vortex. Small droplets are deflected away from the wall by the stagnation flow field and the gas wall-jet flow. While the larger droplets with correspondingly higher momentum are impinged on the wall surface and them are moved along the wall and are rolled up by wall-jet vortex. Using the Watkins and Park's model the predicted results show the most reasonable trend. The rate of increase of spread and the height of the developing wall-spray is predicted to decrease with increased ambient pressure(gas density).

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Experimental Study on Enhanced Jet Grouting by Cavitation Theory (공동현상 이론을 고압분사주입공법에 적용하기 위한 실험적 연구)

  • Lee Sang-Ik;Kim Chang-Jong;Oh Se-Hun;Kim Young-Uk
    • Journal of the Korean Geotechnical Society
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    • v.21 no.1
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    • pp.43-50
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    • 2005
  • Jet grouting method is widely being used in many geotechnical problems, especially for the purpose of reinforcement of clayey ground and cut-off wall of sandy ground. However, its design depends on highly empirical method, in which many researches have been undertaken. This study investigated the effect of cavitation on jet grouting. Small-scaled model tests were carried out using specially designed and fabricated device to analyze the effect of cavitation on jet grouting with various test conditions including ground condition, injection pressure, and injection time. The test results show that cavitation has a significant effect on jet grouting, and it has a potential for engineering application.

Prediction of Propellants Distribution of an Oxidizer Rich Preburner with Honeycomb Array of injectors (벌집형 분사기 배열을 갖는 산화제 과잉 예연소기에서의 추진제 분포 예측)

  • Moon, Il-Yoon;Moon, In-Sang;Lee, Soo-Young
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.614-615
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    • 2010
  • The propellants distribution of an oxidizer rich preburner was predicted by a simplified physical approach. The Mixing head is composed of honeycomb array of 7 fuel injectors and 24 oxidizer injectors. The OF ratio of the mixing head is 15. As results, the OF ratio of the central area is about 9 and the OF ratio of the wall area is about 30.

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Development of Gas Generator for Liquid Rocket Engine to prevent of damage for LOx post (가스 발생기 분사기 LOx post 손상 방지를 위한 분사기 개발)

  • Song Ju-Young;Kim Jong-Gyu;Moon Il-Yoon;Han Yeoung-Min;Choi Hwan-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.353-357
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    • 2005
  • LOx post damage occurs from the development process of the full-scale gas generator which is necessary to 30 tonf class engine development was described. The cause and analysis for damage was described. The combustion test result of 4 injector, the full-scale gas generator and redesigned injector was described. Combustion instability, purge, the low momentum of LOx spray, small recess number, the low flow of LOx, and the high spray angle is main reason the possibility of knowing. The redesign for the injector in the direction of increase of recess number, increase of LOx and fuel spray angle, decrease of gap interval between the LOx post outer wall and fuel screen and increase of LOx post wall thick became accomplished.

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Performance Characteristics for the Gasoline Engine Injector (가솔린엔진 인젝터의 분무특성)

  • Lee, Sang-In;Lee, Sung-Won;Park, Sung-Young
    • Proceedings of the KAIS Fall Conference
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    • 2009.12a
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    • pp.526-530
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    • 2009
  • 본 연구은 자동차용 가솔린엔진에 장착되는 인젝터의 연료공급 특성에 대한 것으로, 가솔린 엔진의 전자제어식 포트 연료분사는 분무장치와 흡기포트의 최적화 및 분무특성이 우수해야 엔진의 성능 향상 및 배기가스 저감의 목적을 이룰 수 있다. 4홀과 12홀 인젝터의 장착각 변화와 포트 마스킹의 형상변화에 따른 벽유량을 측정?분석하였고 분무가시화 실험을 통하여 분무성장과정과 분사각, 연료미립화 및 분무도달거리를 분석하였다. 벽류측정 실험을 통하여 벽류는 미립화정도와 흡기유동과 유속에 가장 큰 영향을 받는 것으로 판단되며, 12홀 인젝터 대비 4홀 인젝터는 분무압력에 따라 분무특성의 변화량이 크게 나타났다.

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A Study on Unsteady Thermal Loading of Hydrogen Engine with Dual Injection (이중분사식 수소기관의 비정상 열부하 해석에 관한 연구)

  • Wei, Shin-Whan;Kim, Yun-Young;Kim, Hong-Jun;Lee, Jong-Tai
    • Transactions of the Korean hydrogen and new energy society
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    • v.12 no.2
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    • pp.147-155
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    • 2001
  • To measure of thermal loading in the combustion chamber of hydrogen engine with dual injection, instantaneous wall-surface temperature and unsteady heat flux of the cylinder head are measured and analyzed. The maximum wall surface temperature is shown in direct injection region which has large heat supplied. Partial and spatial temperatures have slight deviation in transient region of injection, though injection method change suddenly. All of thermal characteristics such as instantaneous temperature, temperature swing and heat flux of hydrogen engine with dual injection are remarkably higher than those of gasoline engine. It means necessity of additional countermeasure of thermal loading.

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The Characteristics of $CO_2 $ Extinguishant Transfer According to the Nozzle Conditions of a Fixed Eire System (고정식 소화장치 노즐조건에 따른 $CO_2 $전달특성)

  • 박찬수;최주석;전철균
    • Fire Science and Engineering
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    • v.18 no.2
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    • pp.41-48
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    • 2004
  • We have conducted a numerical simulation under three-dimensional unsteady conditions in order to analyze the characteristics of $CO_2 $;, extinguishant transfer by varying the location of the injection nozzle, which affects the effect of a $CO_2 $;, fire fighting system used in the form of fixed systems for the marine engine room. Flow fields and $CO_2 $;, concentration fields were measured according to the location of the injection nozzle. In the case of arranging the injection nozzle on the center of the ceiling, the low-normal concentration distribution was developed along the $CO_2 $;, jet due to the downward flow created by impinging ceiling jets in the symmetric plane. The concentration line reaches its peak due to the mass transfer of $CO_2 $;, at the comer.