• Title/Summary/Keyword: Discharge pressure

Search Result 1,478, Processing Time 0.031 seconds

Analysis of payload compartment venting of satellite launch vehicle

  • Mehta, R.C.
    • Advances in aircraft and spacecraft science
    • /
    • v.4 no.4
    • /
    • pp.437-448
    • /
    • 2017
  • The problem of flow through the vent is formulated as an unsteady, nonlinear, ordinary differential equation and solved using Runge-Kutta method to obtain pressure inside payload faring. An inverse problem for prediction of the discharge coefficient is presented employing measured internal pressure of the payload fairing during the ascent phase of a satellite launch vehicle. A controlled random search method is used to estimate the discharge coefficient from the measured transient pressure history during the ascent period of the launch vehicle. The algorithm predicts the discharge coefficient stepwise with function of Mach number. The estimated values of the discharge coefficients are in good agreement with differential pressure measured during the flight of typical satellite launch vehicle.

Study on Pressure Pulsation and Cavity Resonance in Discharge Plenum of Hermetic Compressor (공조용 밀폐형 압축기의 토출부 압력맥동 및 케비티 공명에 대한 연구)

  • 이진갑
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.12 no.3
    • /
    • pp.302-308
    • /
    • 2000
  • The major source of noise in air-conditioner is a compressor. Therefore, noise reduction in a compressor is quite significant as an element technology in air-conditioner field. Recently, a scroll compressor is widely used, because a scroll compressor features lower noise, due to less pulsation of gas pressure, than that of the rotary compressor. During a past noise reduction effort on a scroll compressor, noise radiation from the discharge portion of the hermetic shell was identified as the major contributor to overall noise. For a reduction of noise, the source of noise at the discharge portion must be identified. This paper presents detailed analyzes for the discharge pressure pulsation and cavity resonance at discharge space, which will make possible a low noise design of a scroll compressor.

  • PDF

The Algorithm of Life Time Diagnostics end Evaluating of Exchanges Time about High Pressure Sodium Vapor Lamp Using the LabVIEW Software Package (LabVIEW 소프트웨어 패키지를 이용한 고압나트륨전등의 교환시점 및 수명진단 알고리듬)

  • Han, Tae-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.18 no.6
    • /
    • pp.1-7
    • /
    • 2004
  • It is necessary for starting voltage to him on high pressure discharge lamp. This starting voltage supply to high pressure sodium vapor lamp as electric discharge lamp, Electric field is producted in Electric discharge tube, So accelerative electron collide against vapour atom and second electron is generated, And rapidly the current flow to Electric discharge tube. This paper showed that the life cycle and exchanges time for all electric discharge lamp was different according to each manufactures, This paper is proposed the evaluating algorithm of exchanges time for high pressure sodium vapor lamp, used LabVIEW software package.

Tne Measurements of internal Dynamic Pressure for Development of a High Performance Oil hydraulic Vane Pump(I) (고성능 유압 베인펌프 개발을 위한 내부 변동압력 측정 (I))

  • 정재연;정석훈
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.16 no.2
    • /
    • pp.191-199
    • /
    • 1992
  • This paper presents in experimental study of the dynamic internal pressure within an oil hydraulic vane pump. The measurements of the dynamic internal pressures near the vane of a pressure balance type of an oil hydraulic vane pump with intravanes has been made to provide the essential information for the study of the pump dynamics and control, the pump design and the analysis of tribological problems in the sliding components. The influences of the discharge pressure and rotating speed of the vane on the dynamic pressure in four chambers surrounding a vane have been investigated. The results indicate that the surge pressures of the chambers at the instant moment of discharge and closure are affected by the rotating speed. The pressure in the intravane chamber maintains almost constant values, which remarkably effects the pulsating discharge pressure.

Pressure Variation Characteristics at Trapping Region in Oil Hydraulic Piston Pumps (유압 피스톤 펌프의 폐입 구간에서의 압력 변동 특성)

  • Kwag Jae-ryon;Oh Seok-Hyung;Jung Jae-Youn
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
    • /
    • 2003.11a
    • /
    • pp.329-334
    • /
    • 2003
  • Design of pre-compression region(trapping region) of the valve plate is an important element to minimize the pressure fluctuation in a cylinder and in discharge process, and pump noise. In this study, we tried to prove what the characteristics of the oil hydraulic pump would be according to the angle of the trapping region. Three kinds of asymmetrical valve plates were used. As a result, we found that by designing the trapping region, the slope of the pressure rise in the cylinder port from low-pressure suction region to high-pressure discharge region is relaxed and the pressure fluctuation width and the discharge pressure pulsation are reduced. Therefore, because the pump gets smooth pressure fluctuation and low fluid Impact, the pump noise is reduce.

  • PDF

A Reduction in Pressure Ripples of Axial Piston Pumps of Bent Axis by Phase Interface (위상간섭을 이용한 사축식 액셜 피스톤 펌프의 압력 맥동 감소)

  • Kim, Kyung-Hoon;Park, Kyung-Seok;Jang, Ju-Sub;Kim, Bong-Hwan; Lee, Kyu-Won;Son, Kwon;Shin, Min-Ho
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2003.06a
    • /
    • pp.1261-1265
    • /
    • 2003
  • Axial piston pumps of bent axis have been commonly used in hydraulic systems because of high pressure level. best efficiency, low shear force on pistons and low operating costs. The other side, they have a few demerits like that they have the relatively high number of moving parts and more discharge pressure ripples. Especially, the discharge pressure ripples bring about vibrations and noises in hydraulic system components such as connecting pipes and control valves, so that these deteriorate the stability and accuracy of the systems. Therefore, the hydraulic systems having the axial piston pumps of bent axis require the methods to reduce the discharge pressure ripples. So, the purpose of this paper is to reduce the discharge pressure ripples by the phase interference of pressure wave and to develope the analysis model of the pumps to predict the discharge pressure ripples. In this paper, the analysis model of the axial piston pumps of bent axis was developed using the AMESim software, and the reliability of that was verified by the comparison with the experimental results. The hydraulic pipeline with a parallel line was used as the method to generate the phase interference of pressure wave. the dynamics characteristics of the hydraulic pipeline with a parallel line were analyzed by a transfer matrix method. the usefulness of the phase interference of pressure wave was investigated through the experiment and simulation. The results from the experiment and simulation said that the phase interference of pressure wave by the hydraulic pipeline with a paralle linel could reduce the discharge pressure wave of the pump well. The analysis model of the axial piston pumps of bent axis developed in this paper and the method of the phase interference by the hydraulic pipeline with a parallel line are expected to be helpful to achieve the design of the pump and to reduce the discharge pressure wave of the pump effectively.

  • PDF

The Analysis of Discharge Pressure Noise Characteristics Of Vane Pump for Automatic Transmission (자동변속기용 베인펌프의 토출압 노이즈 특성 해석)

  • Choi, Y.Y.;Choi, H.J.;Lee, S.H.;Jung, W.J.
    • 유공압시스템학회:학술대회논문집
    • /
    • 2010.06a
    • /
    • pp.33-38
    • /
    • 2010
  • As for an oil hydraulic vane pump of vehicle hydraulic systems, the highest of planning technique required by the acquisition of optimum profile data which can be available to predict noises and vibrations. Pressure pulsation may result in considerable vibration and noise of pump component as well as cavitation in hydraulic system. The influences of the discharge pressure and rotating speed of the vane on the dynamic pressure in chamber surrounding a vane have been investigated. It is very important to predict pressure pulsation in vane pump. This paper presents analysis of technique of vane pump for automatic transmission. The predicted result using AMESim model were good agreement with the experimentally obtained results.

  • PDF

Study on blockage after downward discharge of the molten metallic fuel with radiographic visualization

  • Lee, Min Ho;Jerng, Dong Wook;Bang, In Cheol
    • Nuclear Engineering and Technology
    • /
    • v.54 no.1
    • /
    • pp.117-129
    • /
    • 2022
  • The downward discharge of the molten fuel to the lower structure of the fuel assembly could increase of the pressure drop and degrade of coolability of the assembly. To analyze the phenomena, experiments for the generation of the debris bed were conducted as LOF-DT series. Based on the debris bed in the LOF-DT, pressure drop experiment was conducted with intact and blocked component. Parametric study on the pressure drop was conducted by CFD. The LOF-DT experiments were conducted for the position and porosity of the debris bed. 85% of the debris were sedimented in the lower reflector, and 15% were in the nose piece, approximately. Porosity of the debris bed were about 0.7 and 0.85 in the lower reflector and nose piece, respectively. Pressure drop increased significantly with debris bed, especially in the lower reflector. More than 120 time of the pressure drop increased in the lower reflector, while only 10% increased in the nose piece. According to the parametric study, mass of the debris was the most important for pressure drop. The lower discharge phenomena could have a significant effect to the total pressure drop of the fuel assembly, approximately 10.8 times for the base case.

Dynamic Analysis of a Discharge Valve for Electrodynamic Oscillating Compressor (전동형 진동식 압축기 토출밸브의 동적해석)

  • 김형진;박윤식
    • Journal of KSNVE
    • /
    • v.10 no.4
    • /
    • pp.615-622
    • /
    • 2000
  • Discharge valve mechanism for an electrodynamic-oscillating compressor is different from that of a conventional reciprocating compressor. It has a larger discharge port area, heavier valve mass and stiffer valve spring comparing with the reciprocating one. Since the motion of piston is not kinematically restricted as in conventional reciprocating compressors, the stroke of the piston can change sensitively with supplied boltage and load. Thus piston can impact with discharge valve occasionally. This work deals on dynamic analysis of discharge valve considering all of those different characteristics. Impact is considered by a spring-mass model, and the pressure fluctuation at the both sides of the valve is also included considering the discharge port area and valve spring preload. It is assumed that piston moves in the region of between top and bottom dead center not by calculating piston motion from an electrodynamic equation but by getting values through experiment. Discharge pressure fluctuation is calculated using Helmholtz modeling. Finally, dynamic model for a discharge valve is constructed. In order to validate the model analysis results, the valve motion is experimentally measured and compared with analysis.

  • PDF

Measurement of the discharge characteristics of liquid nitrogen at atmospheric pressure by personal computer system (컴퓨터 시스템에 의한 대기압하(大氣壓下)에서 액체질소($LN_2$)의 방전특성측정(放電特性測定))

  • Ju, Jae-Hyun;Lee, Young-Gun;Kim, Sang-Ku;Jeon, Young-Ju;Lee, Kwang-Sik;Lee, Dong-In
    • Proceedings of the KIEE Conference
    • /
    • 1994.07b
    • /
    • pp.1530-1532
    • /
    • 1994
  • This paper describes the discharge characteristics of liquid nitrogen for plane-plane, needle-plane electrode at variation of gap spacing at atmospheric pressure. The important results obtained from this study are as follows. (1) Breakdown voltage of $LN_2$ for needle-plane electrode is higher than that of for plane-plane electrode and discharge duration tine is longer with increase of gap spacing at atmospheric pressure. (2) The formation of bubbles by evaporation is observed in spite of non-applying source at atmospheric pressure and the creation of corona confirmed for plane-plane electrode results from the bubbles. (3) The applied voltage-discharge magnitude( V-Q) characteristics of $LN_2$ showed hysteresis and the discharge magnitude decreasing and corona voltage increasing proportional to the pulse per second at atmospheric pressure.

  • PDF