• Title/Summary/Keyword: Phase explosion

Search Result 100, Processing Time 0.034 seconds

Production and Properties of Ag Metallic Nanoparticle Fluid by Electrical Explosion of Wire in Liquid (유체 내 전기선폭발법에 의한 은 나노입자 유체의 제조 및 특성)

  • Park, E.J.;Bac, L.H.;Kim, J.S.;Kwon, Y.S.;Kim, J.C.;Choi, H.S.;Chung, Y.H.
    • Journal of Powder Materials
    • /
    • v.16 no.3
    • /
    • pp.217-222
    • /
    • 2009
  • This paper presents a novel single-step method to prepare the Ag nanometallic particle dispersed fluid (nanofluid) by electrical explosion of wire in liquid, deionized water (DI water). X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to investigate the characteristics of the Ag nanofluids. Zeta potential was also used to measure the dispersion properties of the as-prepared Ag nanofluid. Pure Ag phase was detected in the nanofluids using water. FE-SEM analysis shows that the size of the particles formed in DI water was about 88 nm and Zeta potential value was about -43.68 without any physical and chemical treatments. Thermal conductivity of the as-prepared Ag particle dispersed nanofluid shows much higher value than that of pure DI water.

KMTNet Supernova Project : The Initial Status

  • Kim, Sang Chul;Moon, Dae-Sik;Lee, Jae-Joon;Pak, Mina
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.40 no.1
    • /
    • pp.56.1-56.1
    • /
    • 2015
  • We are at the initial performance-verification phase of our KMTNet Supernova Project (KSP) using the three wide-field telescopes of the KMTNet in the southern hemisphere. The primary science objectives of KSP, which take advantage of its unique 24-hour continuous sky coverage, are to study early (i.e., within a few hours from explosion) and rare/peculiar (e.g. fast decay) supernovae (SNe), SN progenitors, explosion mechanisms, as well as other exotic optical transients. We present the initial status/results of the program, along with the program strategy, science objectives, target fields, and future plan. While the target field selection will be made based on the performance of the system and consideration of various scientific merits, the initial target fields are focused on nearby galaxies with increased cadence and filter coverage.

  • PDF

Simple P-I diagram for structural components based on support rotation angle criteria

  • Kee, Jung Hun;Park, Jong Yil
    • Advances in concrete construction
    • /
    • v.10 no.6
    • /
    • pp.509-514
    • /
    • 2020
  • In the preliminary design phase of explosion-proof structures, the use of P-I diagram is useful. Based on the fact that the deformation criteria at failure or heavy damage is significantly larger than the yield deformation, a closed form solution of normalized P-I diagram is proposed using the complete plastic resistance curve. When actual sizes and material properties of RC structural component are considered, the complete plasticity assumption shows only a maximum error of 6% in terms of strain energy, and a maximum difference of 9% of the amount of explosives in CWSD. Thru comparison with four field test results, the same damage pattern was predicted in all four specimens.

A Review on Spray Characteristics of Bioethanol and Its Blended Fuels in CI Engines

  • No, Soo-Young
    • Journal of ILASS-Korea
    • /
    • v.19 no.4
    • /
    • pp.155-166
    • /
    • 2014
  • This review will be concentrated on the spray characteristics of bioethanol and its derived fuels such as ethanol-diesel, ethanol-biodiesel in compression ignition (CI) engines. The difficulty in meeting the severe limitations on NOx and PM emissions in CI engines has brought about many methods for the application of ethanol because ethanol diffusion flames in engine produce virtually no soot. The most popular method for the application of ethanol as a fuel in CI engines is the blending of ethanol with diesel. The physical properties of ethanol and its derivatives related to spray characteristics such as viscosity, density and surface tension are discussed. Viscosity and density of e-diesel and e-biodiesel generally are decreased with increase in ethanol content and temperature. More than 22% and 30% of ethanol addition would not satisfied the requirement of viscosity and density in EN 590, respectively. Investigation of neat ethanol sprays in CI engines was conducted by very few researchers. The effect of ambient temperature on liquid phase penetration is a controversial topic due to the opposite result between two studies. More researches are required for the spray characteristics of neat ethanol in CI engines. The ethanol blended fuels in CI engines can be classified into ethanol-diesel blend (e-diesel) and ethanol-biodiesel (e-biodiesel) blend. Even though dodecanol and n-butanol are rarely used, the addition of biodiesel as blend stabilizer is the prevailing method because it has the advantage of increasing the biofuel concentration in diesel fuel. Spray penetration and SMD of e-diesel and e-biodiesel decrease with increase in ethanol concentration, and in ambient pressure. However, spray angle is increased with increase in the ethanol percentage in e-diesel. As the ambient pressure increases, liquid phase penetration was decreased, but spray angle was increased in e-diesel. The increase in ambient temperature showed the slight effect on liquid phase penetration, but spray angle was decreased. A numerical study of micro-explosion concluded that the optimum composition of e-diesel binary mixture for micro-explosion was approximately E50D50, while that of e-biodiesel binary mixture was E30B70 due to the lower volatility of biodiesel. Adding less volatile biodiesel into the ternary mixture of ethanol-biodiesel-diesel can remarkably enhance micro-explosion. Addition of ethanol up to 20% in e-biodiesel showed no effect on spray penetration. However, increase of nozzle orifice diameter results in increase of spray penetration. The more study on liquid phase penetration and SMD in e-diesel and e-biodiesel is required.

Multiphase Flow Modeling of Molten Material-Vapor-Liquid Mixtures in Thermal Nonequilibrium

  • Park, Ik-Kyu;Park, Goon-Cherl;Bang, Kwang-Hyun
    • Journal of Mechanical Science and Technology
    • /
    • v.14 no.5
    • /
    • pp.553-561
    • /
    • 2000
  • This paper presents a numerical model of multi phase flow of the mixtures of molten material-liquid-vapor, particularly in thermal nonequilibrium. It is a two-dimensional, transient, three-fluid model in Eulerian coordinates. The equations are solved numerically using the finite difference method that implicitly couples the rates of phase changes, momentum, and energy exchange to determine the pressure, density, and velocity fields. To examine the model's ability to predict an experimental data, calculations have been performed for tests of pouring hot particles and molten material into a water pool. The predictions show good agreement with the experimental data. It appears, however, that the interfacial heat transfer and breakup of molten material need improved models that can be applied to such high temperature, high pressure, multi phase flow conditions.

  • PDF

A Study on the decision of Scattering distance by Shape of Fragments in LPG Tank lorry Explosion (LPG 탱크로리 폭발시 파편 형상에 따른 비산거리 산정에 관한 연구)

  • Lee, Young Jin;Hwang, Yong Woo;Lee, Ik Mo;Moon, Jin Young
    • Journal of Korean Society of Disaster and Security
    • /
    • v.10 no.2
    • /
    • pp.29-34
    • /
    • 2017
  • LPG is a substance that requires a lot of attention because it can cause fatal damage to people and environment when an accident occurs. LPG is frequently accidents in transportation facilities as well as fixed facilities, among which LPG tank lorries are the most frequent accidents. When the LPG tank is evacuated, the LP gas leaks into two phases, leaks mostly to the gas and leaks to some liquid. At this time, the leaked gas will also sink downward because it is heavier than air, and if it continues to leak, it may form an explosion and explode by the ignition source. The purpose of this study is to present the evacuation distance by analyzing the effect distance of the LPG liquefied petroleum gas in the event of explosion. As a result of calculation of the scattering radius of the fragment, the cylinder fragment was scattered up to 561 m. Therefore, it is appropriate to set the distance to be escaped when the LPG tanker leaks to 561m or more.

TWO-DIMENSIONAL CAVITATION PREDICTION BASED ON APPROXIMATE JACOBIAN MATRIX IN TWO-FLUID TWO-PHASE FLOW MODELS (2-유체 2상-유동 모델에서 근사 Jacobian 행렬을 이용한 2차원 캐비테이션의 예측)

  • Yeom Geum-Su;Chang Keun-Shik
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2005.10a
    • /
    • pp.183-186
    • /
    • 2005
  • We developed an upwind numerical formulation based on the eigenvalues of the approximate Jacobian matrix in order to solve the hyperbolic conservation laws governing the two-fluid two-phase flow models. We obtained eight analytic eigenvalues in the two dimensions that can be used for estimate of the wave speeds essential in constructing an upwind numerical method. Two-dimensional underwater cavitation in a flow past structural shapes or by underwater explosion can be solved using this method. We present quantitative prediction of cavitation for the water tunnel wall and airfoils that has both experimental data as well as numerical results by other numerical methods and models.

  • PDF

A Simple Volume Tracking Method For Compressible Two-Phase Flow

  • SHYUE KEH-MING
    • Journal of The Korean Astronomical Society
    • /
    • v.34 no.4
    • /
    • pp.237-241
    • /
    • 2001
  • Our goal is to present a simple volume-of-fluid type interface-tracking algorithm to compressible two-phase flow in two space dimensions. The algorithm uses a uniform underlying Cartesian grid with some cells cut by the tracked interfaces into two subcells. A volume-moving procedure that consists of two basic steps: (1) the update of volume fractions in each grid cell at the end of the time step, and (2) the reconstruction of interfaces from discrete set of volume fractions, is employed to follow the dynamical behavior of the interface motion. As in the previous work with a surface-tracking procedure for general front tracking (LeVeque & Shyue 1995, 1996), a high resolution finite volume method is then applied on the resulting slightly nonuniform grid to update all the cell values, while the stability of the method is maintained by using a large time step wave propagation approach even in the presence of small cells and the use of a time step with respect to the uniform grid cells. A sample preliminary numerical result for an underwater explosion problem is shown to demonstrate the feasibility of the algorithm for practical problems.

  • PDF

Probabilistic Assesment of the Effects of Vapor Cloud Explosion on a Human Body (증기운 폭발이 인체에 미치는 영향에 대한 확률론적 평가)

  • Yoon, Yong-Kyun;Ju, Eun-Hye
    • Tunnel and Underground Space
    • /
    • v.31 no.1
    • /
    • pp.52-65
    • /
    • 2021
  • In this study, authors analyzed the vapor cloud explosion induced by propane leak at the PEMIX Terminal, which is the propane storage facility outside of Mexico City. TNT equivalence mass for the leaked 4750 kg propane was estimated to be 9398 kg. Blast parameters such as peak overpressure, positive phase duration, and impact at 40-400 (m) away from the center of the explosion were calculated by applying TNT Equivalency Method and Multi-Energy Method. The probability of damage due to lung damage, eardrum rupture, head impact, and whole-body displacement impact by applying the probit function obtained using blast parameters was evaluated. The peak overpressure obtained using Multi-Energy Method was found to be greater than the peak overpressure obtained by applying the TNT Equivalency Method at all distances considered, but it was evaluated that there was no significant difference from the points above 200 m. The peak overpressure obtained by Multi-Energy Method was computed to assess the extent of damage to the structure, and it was shown that structures within 100 m of the explosion center would collapse completely, and that the glasses of the structures 400 m away would be almost broken. The probability of death due to lung damage was shown to vary depending on a human body's position located in the propagating direction of shock wave, and if there is a reflecting surface in the immediate surroundings of a human body, the probability of death was estimated to be the greatest. The impact of shock wave on lung damage, eardrum rupture, head impact, and whole-body displacement impact was evaluated and found to affect whole-body impact < lung damage < eardrum rupture