• Title/Summary/Keyword: Pressure

Search Result 44,763, Processing Time 0.165 seconds

Study on the Design, Manufacture, and Pressure Test of a Pressure Vessel Model (내압용기 모형의 설계, 제작 및 압력시험에 관한 연구)

  • Joung, Tae-Hwan;Lee, Jae-Hwan;Lee, Chong-Moo;Hykudome, Tadahiro;Sammut, Karl;Nho, In-Sik
    • Journal of Ocean Engineering and Technology
    • /
    • v.21 no.6
    • /
    • pp.101-106
    • /
    • 2007
  • In this paper, the authors demonstrate a new idea to take the place of the real pressure vessel test, which should be carried out in a high pressure experiment unit before the real sea trial test. The idea is to make a pressure vessel model as a replica of the real pressure vessel test, which can reduce the cost of making a pressure vessel and large pressure experiment unit. The pressure vessel model was designedbased on linear-elastic, buckling equations and Finite Element Analysis. The manufactured pressure vessel model was investigated and monitored while the pressure test was being conducted. After the test, the result and the validity of the pressure vessel model as a replica of the real pressure vessel test was studied.

A Pressure Stabilization Technique for Incompressible Materials (비압축성 물체의 수치해 안정화 기법)

  • Lee, Sang-Ho;Kim, Sang-Hyo
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.153-160
    • /
    • 1995
  • Mixed finite element formulations for incompressible materials show pressure oscillations or pressure modes in four-node quadrilateral elements. The criterion for the stability in the pressure solution is the so-called Babufka-Brezzi stability condition, and the four-node elements based on mixed variational principles do not appear to satisfy this condition. In this study, a pressure continuity residual based on the pressure discontinuity at element edges is used to study the stabilization of pressure solutions in bilinear displacement-constant pressure four-node quadrilateral elements. It is shown that the pressure solutions, although stable, exhibit sensitivity to the stabilization parameters.

  • PDF

Study on the Improvement of Milling Recovery and Performance(I) -Operational Factors Affecting Rice Milling Performance- (도정수율과 성능향상을 위한 연구(I) -벼의 도정성능에 영향을 주는 작동요인-)

  • 정창주;류관희;박예린;이성범
    • Journal of Biosystems Engineering
    • /
    • v.5 no.2
    • /
    • pp.1-14
    • /
    • 1980
  • This study was carried out to investigate the effects of the counter-pressure setting and the roller speed of a rice whitening machine on the head rice recovery. milling capacity and milling efficiency, and also to find out the optimum operational conditions of the machine. The radial pressure inside the whitening chamber and the outlet axial pressure were measured to study their relationships with the head rice recovery, milling capacity and milling efficiency. The results of the study are summarized as follows. (1) The most important factor in rice whitening was the counter-pressure setting. It significantly affected the head rice recovery. (2) The roller speed significant affected the milling capacity and milling efficiency , but it did not affected the head rice recovery. (3) Both the radial pressure and the outlet axial pressure were affected by the counter-pressure setting but not by the roller speed. Both of them increased almost linearly with the counter-pressure setting. There was a significant correlation between the radial pressure and the outlet axial pressure. (4) The flow rate through the whitening chamber when the feed gate was fully opened increased with the roller speed, but it was not affected by the counter-pressure setting. (5) The head rice recovery decreased as the counter-pressure setting increased , but it was not affected by the roller speed. The reason could be explained by the fact that the radical pressure increased only with the counter-pressure setting. (6) The milling capacity increased with the counter-pressure setting and linearly with the roller speed. The milling efficiency generally increased with both the counter-pressure setting and the roller speed. However, the effect of roller speed was negligible at the higher counter-pressure setting. The temperature rise inside the whitening chamber was moderate with the mean of 11.3℃ (range 5.6-18.3℃) even though it increased slightly with the roller speed. Considering the head rice recovery and milling efficiency, the optimum operational conditions of the machine appeared to be the counter-pressure setting of 67g/㎠ and the roller speed of 1,050rpm. Neglecting the small difference in the head rice recovery , the greater milling capacity could be obtained at the counter-pressure setting of 85g/㎠ with the roller speed of 850-1050rpm.

  • PDF

Development of Blood Pressure Simulator for Test of the Arm-type Automatic Blood Pressure Monitor (팔뚝형 자동혈압계 평가용 혈압 시뮬레이터 개발)

  • Kim, S.H.;Yun, S.U.;Cho, M.H.;Lee, S.J.;Lim, M.H.;Seo, S.Y.;Jeon, G.R.
    • Journal of Sensor Science and Technology
    • /
    • v.24 no.4
    • /
    • pp.239-246
    • /
    • 2015
  • Blood pressure is possible to diagnose a disease associated with blood pressure and judgment the current health of patients. Automatic blood pressure monitor capable of measuring a blood pressure easily in hospital and at home have become spread. In this study, we developed the blood pressure simulator (BPS) that can test the arm-type automatic blood pressure monitor that is commonly used in hospital. BPS is to produce a pressure similar to the pressure wave generated in the human blood using a servo disk motor. Then, using the silicon tube, it implements the situations such as human blood vessels, and to output the generated pressure waveform. Simply the BPS's phantom put on the cuff and it is able to simulate blood pressure. So anyone can quickly test the blood pressure monitor within one minute and it is possible to shorten the test time required for the automatic blood pressure monitor. In Performance test, the trends and the standard deviation of the values measured in the BPS is similar to the value of the measured pressure from people with normal blood pressure. Thus, the development BPS showed a possibility of taking into account the actual blood pressure measurement environment simulator.

Influence of changing Combustor Pressure on Flame Stabilization and Emission Charncteristics (연소실 압력변동이 화염안정화와 배출특성에 미치는 영향)

  • Kim, Jong-Ryul;Choi, Gyung-Min;Kim, Duck-Jool
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.2354-2359
    • /
    • 2007
  • Influence of changing combustor pressure on flame stabilization and emission index in the swirl-stabilized flame was investigated. The combustor pressure was controlled by suction fan at combustor exit. Pressure index ($P^{\ast}$=Pabs/Patm), where Pabs and Patm indicated the absolute pressure and atmosphere pressure, respectively, was controlled in the range of 0.7${\sim}$1.3 for each equivalence ratio conditions. The flammable limits of swirl flames were largely influenced by changing combustor pressure and they showed similar tendency with laminar flames. NOx emission index decreased with decreasing pressure index for overall equivalence ratio conditions. R.m.s. of pressure fluctuations is increased with decreasing combustor pressure. This flame fluctuation caused incomplete combustion, hence CO emission index increased. These oscillating flames were measured by simultaneous $CH^{\ast}$ chemiluminescence time-series visualization and pressure fluctuation measurement.

  • PDF

The Effects of Injector Nozzle Geometry and Operating Pressure Conditions on the Transient Fuel Spray Behavior

  • Koo, Ja-Ye
    • Journal of Mechanical Science and Technology
    • /
    • v.17 no.4
    • /
    • pp.617-625
    • /
    • 2003
  • Effects of Injector nozzle geometry and operating pressure conditions such as opening pressure, ambient pressure. and injection pressure on the transient fuel spray behavior have been examined by experiments. In order to clarify the effect of internal flow inside nozzle on the external spray, flow details Inside model nozzle and real nozzle were alto investigated both experimentally and numerically. for the effect of injection pressures, droplet sizes and velocities were obtained at maximum line pressure of 21 MPa and 105 MPa. Droplet sizes produced from the round inlet nozzle were larger than those from the sharp inlet nozzle and the spray angle of the round inlet nozzle was narrower than that from the sharp inlet nozzle. With the increase of opening pressure, spray tip penetration and spray angle were increased at both lower ambient pressure and higher ambient pressure. The velocity and size profiles maintained similarity despite of the substantial change in injection pressure, however, the increased injection pressure produced a higher percentage of droplet that are likely to breakup.

Effects of Distance between Pads on the Film Pressure in Pad Bearings (패드 베어링에서 패드사이의 거리가 유막압력에 미치는 영향)

  • Kim, Jong-Soo;Kim, Kyung-Woong
    • Tribology and Lubricants
    • /
    • v.13 no.1
    • /
    • pp.53-61
    • /
    • 1997
  • Experiments are conducted to investigate the effects of distance between pads on the film pressure and the inlet pressure build-up at the entrance of pad bearings. The inlet pressure and the film pressure are measured by manometers in several cases of the distance between pads. The experimental results are also compared with the theoretical results which are calculated using the several methods for the estimation of the inlet pressure. In the experimental results , the distance between pads has a large influence on the film pressure and the inlet pressure build-up a bearing entrance. It is also shown that the effects of the inlet pressure on the film pressure are remarkable, although inertia parameter is a little higher (${\ge}0.05$).

A Study on The Explosion Characteristics of Flammable Gases (가연성 가스의 폭발특성에 대한 연구)

  • 오규형;김한석;이춘하
    • Journal of the Korean Society of Safety
    • /
    • v.7 no.3
    • /
    • pp.66-72
    • /
    • 1992
  • An experimental study was carried out to analyse the explosion characteristics of flammable gas-air mixtures. Used flammable gases were hydrogen, methane, acethylene, ethylene and pro-pane, explosion Pressure, explosoin pressure rising rate, and flame propagation velocity were measured experimentaly. The maximum explosion pressure and rising rate of flammmalbe gas air mixtures were appeared at the range of slightly higher concentration than the stoichiometric concentration. Initial pressure before explosion was controlled from 0.6 to 2.0kg/cm absolutly. Explosion pressure was increased with increment of the initial pressure, and the relationship between initial pressure and explosion pressure was Pe = KPi. The effect of vessel size on explosion characteristics was also analysed In this experiment. Explosion pressure was increased with in-creasing the vessel size, otherwise explosion pressure rising rate was decreased. When we locate a dummy material in vessel explosion pressure was decreased with increasing the dummy volume but exlosion pressure rising rate was increased.

  • PDF

A Study on the Performance Characteristics of Low Pressure Hydraulic Circuit of Common Rail System (커먼레일 시스템용 저압 유압회로의 성능특성에 관한 연구)

  • Lee, Choon-Tae
    • Journal of Power System Engineering
    • /
    • v.18 no.6
    • /
    • pp.51-57
    • /
    • 2014
  • High pressure common rail injection technology has revolutionized the diesel industry. Over the last decade it has allowed engine builders to run higher injection pressures as much as above 1,300bar in order to increase engine efficiency, while reducing emissions. This common rail system has low pressure circuit which is consist of low pressure pump, cascade overflow valve and flow metering unit. The low pressure pump's purpose is to feed fuel oil to the high pressure pump. The cascade overflow valve keeps pressure in front of the metering unit constant and provides lubrication for the high pressure pump. The metering unit, known as the MPROP or fuel pressure regulator, regulates the maximum flow rate delivers to the rail. In this paper, we have investigated the performance characteristics of each components and total low pressure circuit of common rail system.

The Effect of Air Vent Holes and Stacking Methods of Fruits and Vegetables Boxes on Static Pressure Drop in Pressure Cooling System (청과물상자의 통기공 및 상자적재방법이 정압강하에 미치는 영향)

  • 김의웅;김병삼;남궁배;정진웅;김동철;금동혁
    • Journal of Biosystems Engineering
    • /
    • v.20 no.4
    • /
    • pp.360-367
    • /
    • 1995
  • The effect of air vent holes, stacking methods of boxes and clearance between boxes on static pressure drop, were measured to design of pressure cooling system. Static pressure drops in air vent hole of carton box were measured for different hole opening ratio from 1% to 5%. Static pressure drop was expressed as a function of superficial velocity as second-degree polynomial. At given static pressure in plenum chamber, static pressure drop in boxes was shown as second-degree polynomial of the number of carton box in series stacking method, as first-degree polynomial in height and parallel stacking method. In pressure cooling of 24 boxes of Tsugaru apple, air flow rates through clearance between the boxes were shown 1.27 and 1.65 times than those of through the inside of boxes at the plenum pressure of 10mmAq and 20mmAq, respectively.

  • PDF