• Title/Summary/Keyword: Frozen flow

Search Result 137, Processing Time 0.023 seconds

Numerical Analysis of Hypersonic Flow over Small Radius Blunt Bodies (작은 크기의 무딘 물체에 대한 극초음속 유동의 수치해석)

  • Lee Chang Ho;Park Seung O
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2002.05a
    • /
    • pp.109-114
    • /
    • 2002
  • The effect of nose radius on aerodynamic heating are investigated by using the Wavier-Stokes code extended to thermochemical nonequilibrium airflow. A spherical blunt body, whose radius varies from 0.003048 m to 0.6096 m, flying at Mach 25 at an altitude of 53.34 km is considered. Comparison of heat flux at stagnation point with the solution of Viscous Shock Layer and Fay-Riddell are made. Obtained result reveals that the flow chemistry for very small radius is nearly frozen, and therefore the contribution of heat flux due to chemical diffusion is smaller than that of translational energy. As the radius becomes larger, the portion of diffusion heat flux becomes greater than translational heat flux and approaches to a constant value.

  • PDF

TRANSIENT SIMULATION OF SOLID PARTICLE DISTRIBUTION WITH VARIOUS DESIGN PARAMETERS OF THE BAFFLE IN A STIRRED TANK (배플 형상에 따른 교반기 내부 고체입자 분포의 비정상상태 해석)

  • Kim, Chi-Gyeom;Lee, Seung-Jae;Won, Chan-Shik;Hur, Nahm-Keon
    • Journal of computational fluids engineering
    • /
    • v.14 no.4
    • /
    • pp.1-6
    • /
    • 2009
  • In the present study, numerical simulations were performed in a stirred solid/liquid system by using Eulerian multi-phase model. The transient flow field of liquid and distribution of solid particles were predicted in the stirred tank with pitched paddle impeller and baffles. The Frozen rotor method is adopted to consider the rotating motion of the impeller. The effects of number and width of baffles on the mixing time and the quality of solid suspension in the stirred tank are presented numerically. The result shows that the mixing time decreases as the width and number of baffles increase. The present numerical methodology can be applied to optimizing mixing condition of industrial mixer.

The Effect of Nitric Oxide, Isosorbide Dinitrate and Sodium Nitroprusside on Ischemic Myocardium of Rat (Nitric oxide, Isosorbide dinitrate 및 Sodium nitroprusside가 쥐의 허혈성 심근에 미치는 영향)

  • Jeong, Jong-Hwa;Kim, Su-Hyeon;Kim, Song-Myeong
    • Journal of Chest Surgery
    • /
    • v.29 no.10
    • /
    • pp.1055-1065
    • /
    • 1996
  • This experiment was undertaken to assess the effect of nitric oxide, isosorbide dinitrate, and sodium nitroprusside, which are known to increase coronary flow by vasodilation and to improve the cardiac function of an ischemic heart The experiment was carried out to investigate the effect of nitric oxide on the coronary artery of an ischemic rat myocardium using isolated constant pressure Langendorfr system. The experimental parameters were lactate and CK-MB for the frozen myocardium and coronary flow. the quantity of coyonary flow, left ventricular developed pressure (LVDP), and dp/dt. The experimental groups were decided as control group (Group I), nitric oxide group (Group II), Iso orbide dinitrate group (Group III) and sodium nitroprusside group (Group IV). Statistical analysis was performed using repeated measured analysis of variance and 2tudent t-test The results were as follows: 1 . The lactic acid contents of group II and IV were less than other groups for the frozen myocardium at preischemic state (p< 0.0025), whereas the determined coronary flows were higher. 2. In the ratio of produced lactic acid between the preischemia and reperfusion for the coronary flow, group II and IV exhibitrod less value than others (p< 0.005). 3. Group II and III were less than others in the coronary flow for the quantity of CK-MB, but or the frozen myocardium, group II and IV were less. 4. Group II and IV showed higher coronary flow compared to others throughout entire experimental period (p< 0.005). 5. Group II was highest at the preischemic state for the left ventricular developed pressure. 6. The +maximal dp/dt of group II was highest compared to others. 7. Group I exhibi ed the highest recovery rate of coronary flow between prelschemla and reperfusion. 8. The(-dp/dt)1(+dp/dt) ratio was 116%, 100%, 100%, and 55% for the 4 groups, respectively And the recovery rate of total dp/dt was 34%, 67%, 51%, and 76% for the four groups, respectively.

  • PDF

Growth and mortality of the juvenile common octopus (Octopus vulgaris) in pipe- and tire-type shelters placed in flow-through seawater tanks

  • Kwon, Inyeong;Kim, Taeho
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.51 no.1
    • /
    • pp.1-8
    • /
    • 2015
  • The common octopus, which has a high growth rate and high market price, is a prime candidate for commercial marine aquaculture operations. We evaluated the effectiveness of two types of shelters (pipe and tire types) for juvenile common octopus growing out in flow-through seawater tanks. Growth rates were evaluated in two experiments. The first experiment (Experiment 1) ran for 72 days, and the second (Experiment 2; replicated) ran for 46 days. Each trial included 40 octopuses fed a diet of frozen sardine (Sardinops melanostictus) and swimming crab (Portunustri tuberculatus) at 3-8% of body weight once every 3 days. In the two experiments, the respective specific growth rates were 0.3 and 0.04%/day in pipe-type shelters and 0.00 and 0.88%/day in tire-type shelters, while the respective percentage survivals were 80 and 80% in pipe-type shelters and 70 and 90% in tire-type shelters. Shelter type had little influence on the growth rate (P < 0.05).

Measurement and Analysis of Showcase Field Data (쇼케이스의 현장 데이터 측정 및 분석)

  • Shin You-Hwan;Oh Wang-Kyu;Park Ki-Ho;Kim Youngil;Shin Younggy
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.17 no.5
    • /
    • pp.436-443
    • /
    • 2005
  • Experimental study was performed to understand the operation of an on-site showcase working in a super discount store. Inlet and outlet temperatures of evaporator, condenser, expansion valve and compressor were measured for both air and refrigerant sides. Electric power consumption of compressors, defrosting heaters, cooling water pumps and etc. were measured. The operating characteristics of the showcase system under various working conditions were analyzed and discussed. During the defrosting process, the air temperature inside the showcase increased to $15^{\circ}C$, which gave harmful effect to the frozen food. The collected data will serve as valuable information for diagnosing and improving the performance of showcases.

A Study for Rocket Exhaust Flow Cooling due to the Central Spray Type Water Injection (중앙 분사 방식 냉각수 투입에 의한 로켓 연소 후류 냉각에 관한 연구)

  • Kang, Sun-Il;Nam, Jung-Won;Huh, Hwan-Il
    • Aerospace Engineering and Technology
    • /
    • v.12 no.1
    • /
    • pp.163-172
    • /
    • 2013
  • In this study, the cooling of rocket exhaust plume by sprayed water inside plume were investigated as varying of sprayed water mass, location, and method using computational fluid analysis. For Analyze rocket exhaust plume, a single species unreacted analysis model based on the chemically frozen analysis was used and the discrete particle model which was a kind of Euler-Lagrangian analysis model was used for simulate sprayed water inside plume. It was confirmed that the temperature of plume was reduced without cooling when water mass was two times of plume mass through analysis results.

Numerical Study on Laser-driven In-Tube Accelerator (LITA) Performance using a Plasma Size Modeling

  • Kim, Sukyum;Toshiro Ohtani;Akihiro Sasoh;Jeung, In-Seuck;Park, Jeong--Yeol
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2004.03a
    • /
    • pp.320-324
    • /
    • 2004
  • Laser Propulsion is a device that generates thrust using laser energy. Laser-driven In-Tube Accelerator (LITA) has been developed at Tohoku University. LITA is a laser propulsion system that accelerates an object not in an open air but in a tube. Experiments of vertical launching and pressure measurement on the tube wall were carried out and in order to observe the initial state of plasma and blast wave, the visualization experiment was carried out using the shadowgraph method. In this study, the time variation of pressure on the tube wall is numerically simulated solving Euler equation. In order to model the laser energy, heat source function added to the frozen flow Euler equation. Plasma size from the shadowgraph images was used for the initial condition of laser energy input. For verification of the modeling, these results were compared with the previous experimental and numerical results. From these verifications, an analysis of LITA performance will be investigated.

  • PDF

Rheological Properties of Rehydrated Suspensions of Freeze Dried Kochujang Powders (동결건조 분말고추장의 재수화시 리올로지 특성)

  • Kim, Suk-Shin;Chang, Kyu-Seob;Yoon, Han-Kyo;Lee, Sang-Kyu;Lee, Shin-Young
    • Korean Journal of Food Science and Technology
    • /
    • v.19 no.2
    • /
    • pp.81-88
    • /
    • 1987
  • Rheological properties of rehydrated suspensions of two kinds of freeze dried Kochujang powders, processed at different freezing rates, were compared with raw Kochujang using Brookfield wide-gap rotational viscometer at $25^{\circ}C-60^{\circ}C$. Shear rates ranged from $0.1965\;sec^{-1}$ to $1.9650\;sec^{-1}$ and solid content ranged from 47% to 56%. Rehydrated suspensions of quickly frozen Kochujang powder and slowly frozen Kochujang powder, and raw Kochujang exhibited pseudoplastic behaviors with yield stress and presented thixotropic properties which followed the second-order kinetic behavior proposed by Tiu. Suspensions of Kochujang powders exhibited considerably higher decaying rates than raw Kochujang. The dependency of the equilibrium structure parameter on the shear rate was weak, and there were no significant differences among the values of structure parameters of three samples. The temperature dependency of the apparent viscosity of Kochujang suspension was fully expressed by Arrhenius equation and activation energies of suspensions of quickly frozen Kochujang powder and slowly frozen Kochujang powder, and raw Kochujang were 2.21, 2.18, and 2.32 Kcal/g.mole respectively. Consistency indices of three samples increased with solid content and decreased with temperature. Flow behavior indices of three samples showed no considerable dependency on the temperature and solid content. There were no significant differences in the rheological properties between two Kochujang powders.

  • PDF

Analysis on Artificial Insemination Failure and Characteristics of Frozen Semen Used for Reproduction of Hanwoo Cow in Gangwon East Area (강원 영동지방 암소 인공수정에 이용된 한우보증씨수소 정액의 인공수정 실패율 분석 및 동결정액성상 분석)

  • Park, Sai-Rom;Hong, Min-Wook;Kim, Hun;Lee, Seung-Kyu;Lee, Yeung-Sub;Kim, Jin-Woo;Lee, Hak-Kyo;Jeong, Dong-Kee;Kim, Jong-Bok;Song, Young-Han;Lee, Sung-Jin
    • Reproductive and Developmental Biology
    • /
    • v.36 no.1
    • /
    • pp.27-32
    • /
    • 2012
  • This study was carried out to investigate artificial insemination (AI) failure status and frozen semen characteristics in Korean proven bulls' number (KPN) semen used for AI of Hanwoo cows in Gangwon East region (Gangneung, Donghae, Taebaek, Samcheok, Sokcho, Yangyang, Goseong). Among semen used for AI, AI failure rate showed lowest at KPN506 (27.6%), whereas highest at KPN593 (77.2%). Correlations of AI failure in between Korean proven bulls semen and cows was 0.2941, which means that AI failure rate of Korean proven bulls semen may have respectable effect on reproduction of Hanwoo cow. In addition, present study was conducted to investigate spermatozoal viability rate, ruptured acrosome rate and active mitochondria in frozen Korean proven bulls semen with flow cytometry. The semen of KPN593 showed significantly ($p$<0.05) higher viability rate in KPN593 (30.49%) than that in KPN637 (37.34%). Furthermore, percentage of ruptured acrosome was lower in KPN637 as 21.37% than in KPN637 (21.37%), but it was not statistically significant. In conclusion, these results indicate that choice of Korean proven bulls semen may correlate positively with conception rate in Hanwoo cow. Therefore, KPN with high AI failure rate might be avoid to increase conception rate and characteristics of frozen semen might be evaluated before its use for AI.

Analysis of Sexed Sperm by Flow Cytometry in Hanwoo (Korean Native Cattle)

  • Yoo, Han-Jun;Lee, Kyung-Jin;Lee, Yong-Seung;Yoon, Pil-Sang;Park, Joung-Jun;Kim, Hyeong-Cheol;Park, Choon-Keun
    • Reproductive and Developmental Biology
    • /
    • v.36 no.1
    • /
    • pp.1-6
    • /
    • 2012
  • This study evaluated a sexed sperm ability to produce embryos by flow cytometer. Hanwoo bulls sperm were separated to X and Y sperm via Hoechst 33342 stained with near UV laser or performed the pre-sorted without near UV laser beam in flow cytometry. Pre-sorted sperm had significantly higher viability ($84{\pm}1.15%$, $p$<0.05) compared to other sorted groups in frozen-thawed semen. For fresh semen, pre-sorted sperm had the higher viability ($79{\pm}3%$, $p$<0.05) than those of the X and Y sperm ($44.7{\pm}1.67$ and $41.7{\pm}1.2%$) separated by differences of DNA content. On the other hand, pre-sorted and X sperm sorted according to differences in DNA content had significantly higher viabilities ($24.3{\pm}1.2$ and $25.7{\pm}0.9%$, $p$<0.05) compared to that of the sorted Y sperm ($13.7{\pm}1.2%$) in the hypoosmotic swelling test. The proportion acrosome reaction in the sorted X sperm was higher ($55.0{\pm}1.7$ and $45.0{\pm}1.5%$) than those of the sorted Y-sperm ($32.3{\pm}0.9%$, $p$<0.05). However, the sperm morphologies of the sorted groups were not significantly differences. In conclusion, the sex-sorting procedure by flow cytometry affected some characteristics of Hanwoo sperm. Further study is needed to determine the optimal procedures to enhance male and female embryos and sorting accuracy.