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  • Title/Summary/Keyword: Air blast

검색결과 323건 처리시간 2.534초

Optimal Mesh Size in Three-Dimensional Arbitrary Lagrangian-Eulerian Method of Free-air Explosions (3차원 Arbitrary Lagrangian-Eulerian 기법을 사용한 자유 대기 중 폭발 해석의 최적 격자망 크기 산정)

  • Yena Lee;Tae Hee Lee;Dawon Park;Youngjun Choi;Jung-Wuk Hong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • 제36권6호
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    • pp.355-364
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    • 2023
  • The arbitrary Lagrangian-Eulerian (ALE) method has been extensively researched owing to its capability to accurately predict the propagation of blast shock waves. Although the use of the ALE method for dynamic analysis can produce unreliable results depending on the mesh size of the finite element, few studies have explored the relationship between the mesh size for the air domain and the accuracy of numerical analysis. In this study, we propose a procedure to calculate the optimal mesh size based on the mean squared error between the maximum blast pressure values obtained from numerical simulations and experiments. Furthermore, we analyze the relationship between the weight of explosive material (TNT) and the optimal mesh size of the air domain. The findings from this study can contribute to estimating the optimal mesh size in blast simulations with various explosion weights and promote the development of advanced blast numerical analysis models.

Breakup Characteristics in Plain Jet Air Blast Atomizer(I)-Jet Breakup and Internal Flow- (2유체 분무노즐의 분열특성(I)-액주분열 및 내부유동-)

  • Kim, Hyeok-Ju;Lee, Chung-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • 제21권8호
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    • pp.1009-1023
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    • 1997
  • The breakup length of a liquid jet with flowrate, formed by releasing through a nozzle of circular cross-section into the atmosphere, was experimented and studied for 3 liquid nozzles of varying diameters. The experimental result was analyzed using the existing theoretical equation for predicting the breakup length. It was found that the breakup length of liquid jet depends on the velocity, and the breakup length increases with increasing of the liquid nozzle diameter. Also, the variation range of the breakup length for the same flowrate of liquid increased rapidly as velocity was increased for laminar flow, but in the turbulent flow region, it leveled off in the range of approximately 0.55-0.7 of the mean breakup length. Furthermore, when the longest smooth liquid jet was applied to the co-axial flow air blast atomizer, the effect of air flow on the flow pattern and breakup length was studied for 6 glass nozzles of different lengths and diameters. It was found that depending on the diameter of the mixing tube and liquid jet, it was possible to observe a wide range of flow patterns, such as liquid jet through flow, partial annular flow and annular flow. The liquid jet breakup length was more sensitive to the change in the length rather than the diameter of the mixing tube. As the length of the mixing tube shortens, the breakup length also shortens rapidly.

Fluidity of Cement Paste with Air-Cooled Blast Furnace Slag (고로 서냉슬래그 혼합 시멘트 페이스트의 유동성)

  • Lee, Seung-Heun;Park, Seol-Woo;Yoo, Dong-Woo;Kim, Dong-Hyun
    • Journal of the Korean Ceramic Society
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    • 제51권6호
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    • pp.584-590
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    • 2014
  • Air-cooled slag showed grindability approximately twice as good as that of water-cooled slag. While the studied water-cooled slag was composed of glass as constituent mineral, the air-cooled slag was mainly composed of melilite. It is assumed that the sulfur in air-cooled slag is mainly in the form of CaS, which is oxidized into CaS2O3 when in contact with air. CaS2O3, then, is released mainly as S2O32ion when in contact with water. However, the sulfur in water-cooled slag functioned as a constituent of the glass structure, so theS2O32 ion was not released even when in contact with water. When no chemical admixture was added, the blended cement of air-cooled slag showed higher fluidity and retention effect than those of the blended cement of the water-cooled slag. It seems that these discrepancies are caused by the initial hydration inhibition effect of cement by the S2O32 ion of air-cooled slag. When a superplasticizer is added, the air-cooled slag used more superplasticizer than did the blast furnace slag for the same flow because the air-cooled slag had higher specific surface area due to the presence of micro-pores. Meanwhile, the blended cement of the air-cooled slag showed a greater fluidity retention effect than that of the blended cement of the water-cooled slag. This may be a combined effect of the increased use of superplasticizer and the presence of released S2O32 ion; however, further, more detailed studies will need to be conducted.

Far Infrared Rays Drying Characteristics of Tissue Cultured Mountain Ginseng Roots (산삼배양근의 원적외선 건조특성)

  • Li, H.;Kwang, T.H.;Ning, X.F.;Cho, S.C.;Han, C.S.
    • Journal of Biosystems Engineering
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    • 제34권3호
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    • pp.175-182
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    • 2009
  • This study was conducted to investigate the drying characteristics of tissue cultured mountain ginseng roots. The far infrared rays dryer of a double blast system used for this experiment can control the drying parameters such as far infrared heater temperature and air velocity. The far infrared rays drying tests of tissue cultured mountain ginseng roots were performed at air velocity of 0.4, 0.6, 0.8 m/s, under drying air temperature of 50, 60, and 70circC, respectively. The results were compared with one obtained by the heated air drying method. The drying characteristics such as drying rate, color, energy consumption, saponin components and antioxidant activities were analyzed. The results showed that the drying rate of far infrared rays drying was faster than that of heated air drying and due to high temperature of drying air and fast air velocity, the far infrared rays drying of double blast type was superior to the heated air drying. The value of the color difference for heated air drying was 10.1112.99 and that of far infrared rays drying was in the range of 7.057.54, which was in the same drying condition, also energy consumption of far infrared rays drying was in the range of 35756898 kJ/kg-water. At the same time, the antioxidant activities using far infrared rays drying were higher than those using heated air drying.

Experimental Study on Mechanical Properties of Carbon-Capturing Concrete Composed of Blast Furnace Slag with Changes in Cement Content and Exposure (고로슬래그 기반 탄소흡수용 콘크리트의 시멘트 첨가율 및 노출조건에 따른 역학적 특성 분석을 위한 실험적 연구)

  • Cho, Hyun Myung;Kim, Seung Won;Song, Ji Hyeon;Park, Hee Mun;Park, Cheol Woo
    • International Journal of Highway Engineering
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    • 제17권4호
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    • pp.41-51
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    • 2015
  • PURPOSES: This study investigates the mechanical performance of carbon-capturing concrete that mainly contains blast furnace slag. METHODS: The mixture variables were considered; these included Portland cement content, which was varied from 10% to 40% of the blast furnace slag by weight. The specimens were exposed to different conditions such as high N2 and O2 concentrations, laboratory conditions and high CO2 conditions. Mechanical performances, including compressive and flexural strengths and carbon-capturing depth, were evaluated. RESULTS : The slump, air content and unit weight were not affected significantly by the variation in cement content. The strength development when the specimens were exposed to high purity air was slightly greater than that when exposed to high CO2. As the cement content increased the compressive and flexural strength increased but not considerably. The carbon-capturing capacity decreased as the cement content increased. The specimens exposed in the field for 70 days had flexural strength greater than 3 MPa. CONCLUSIONS : The results indicate that cement content is not an important parameter in the development of compressive and flexural strengths. However, the carbon-capturing depth was higher for less cement content. Even after field exposure for 70 days, neither any significant damage on the surface nor any decrease in strength was observed.

Fundamental Characteristics of Carbon-Capturing and Sequestering Activated Blast-Furnace Slag Mortar (탄소포집 활성 고로슬래그 모르타르의 기초특성에 관한 연구)

  • Jang, Bong Jin;Kim, Seung Won;Song, Ji Hyeon;Park, Hee Mun;Ju, Min Kwan;Park, Cheolwoo
    • International Journal of Highway Engineering
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    • 제15권2호
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    • pp.95-103
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    • 2013
  • PURPOSES : To investigate the fundamental characteristics of blast-furnace slag mortar that was hardened with activating chemicals to capture and sequester carbon dioxide. METHODS : Various mix proportions were considered to find an appropriate stregnth development in regards with various dosages of activating chemicals, calcium hydroxides and sodium silicates, and curing conditions, air-dried, wet and underwater conditions. Flow characteristics was investigated and setting time of the mortar was measured. At different ages of 3, 7 and 28days, strength development was investigated for all the mix variables. At each age, samples were analyzed with XRD. RESULTS : The measured flow values showed the mortar lost its flowability as the activating chemicals amount increased in the scale of mole concentration. The setting time of the mortar was relatively shorter than OPC mortar but the initial curing condition was important, such as temperature. The amount of activating chemicals was found not to be critical in the sense of setting time. The strength increased with the increased amount of chemicals. The XRD analysis results showed that portlandite peaks reduced and clacite increased as the age increased. This may mean the Ca(OH)2 keeps absorbing CO2 in the air during curing period. CONCLUSIONS : The carbon capturing and sequestering activated blast-furnace slag mortar showed successful strength gain to be used for road system materials and its carbon absorbing property was verified though XRD analysis.

A fundamental Study on the properties of Concrete by using the Rapid Hardening Blast Furnace Slag Cement (조강슬래그시멘트를 이용한 콘크리트의 기초물성에 관한 연구)

  • 김진춘;최광일
    • Proceedings of the Korea Concrete Institute Conference
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    • 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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    • pp.72-77
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    • 1995
  • Blast-furnace slag cement has been used widely as a structural material due to the latent hydraulicity of granulated ground blast furnace slag(GGBS)for a long time as The wall as ordinary portland cement. In this study, based on the fundamental investigation on the high strength and high durable concrete using the high fineness GGBS the following remarks can be made. 1) The average desired strenth of concrete is Or=600~800kg/cm2. 2) The above high strength concrete using the high fineness GGBS is more workable than those using only OPC. 3) The adiabatic temperature and drying shringkage decrease, so the density and resistance to sea water attack increase as results. 4)The unit cement content and unit air entrained admixture at the same desired strength of concrete decrease, so the economical high strength concrete can be manufactured from using the high fineness GGBS.

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Properties of Low Heat Concrete Using Blast Furnace Slag Powder and Gypsum (고로슬래그 미분말과 석고를 사용한 저발열 콘크리트의 특성)

  • Cho, Il-Ho;Kim, Young-Ik;Sung, Chan-Yong
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 한국농공학회 2002년도 학술발표회 발표논문집
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    • pp.145-148
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    • 2002
  • This study is performed to properties of low heat concrete using blast furnace slag powder and gypsum. The test result shows that the air content is in the range of 4.1, the unit weight is in the range of 2,306kg/m32,334kg/m3. The compressive strength of concrete mixed blast furnace slag(BFS) low than ordinary portland cement(OPC) at the curing age of 7days, but it is high or same at the curing age of 28days. And the natural gypsum shows superior compressive strength than the chemical gypsum.

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A Study on the property of the Blast-Furnace Slag as Fine Aggregate of Concrete (콘크리트용 잔골재로써 고로 수쇄슬래그의 특성연구)

  • Kim, D.S.;Ha, S.W.;Koo, B.C.;Ha, J.D.;Lee, J.R.;Chae, J.H.
    • Proceedings of the Korea Concrete Institute Conference
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    • 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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    • pp.269-274
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    • 2000
  • As a result of the reduction of natural aggregate, most of developed country have been studied the utilization of Blast-furnace Slag(BFS) as aggregate of concrete. bur, in korea there are only basic study about these even though other country are using Blast-furnace Slag production of Ready Mixed Concrete. According, in this study, we carried out fundamental experiments in order to know the material properties of BFS and possibilities of the BFS as fine aggregate of concrete. It is included that analysis concerning material properties of BFS as like specific gravity, absorption. unit weigth, grading including investigation of the surface shape by SEM, also, analysis concerning properties of concrete with BFS as like air-content surface slump. compressive strength .etc.

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