• Title/Summary/Keyword: Nozzle Pressure

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Comparison of Spray Characteristics between Conventional and Electrostatic Pressure-Swirl Nozzles

  • Laryea, G.N.;No, S.Y.
    • Journal of ILASS-Korea
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    • v.11 no.1
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    • pp.24-29
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    • 2006
  • Spray characteristics produced by conventional and electrostatic pressure-swirl nozzles for an oil burner have been studied, using kerosine as a test liquid. The charge injection mechanism is used to design the electrostatic nozzle, where specific charge density, breakup length, spray angle and mean diameter are measured and analyzed. Three nozzles with orifice diameters of 0.256, 0.308 and 0.333mm at injection pressures of 0.7, 0.9, 1.1 and 1.3 MPa are used in the study. In case of the electrostatic nozzle, voltages ranging from -5 to -12kV are applied. Comparison of the spray characteristics is made between the conventional and electrostatic nozzles. The results showed that, the electrostatic nozzle is superior to the conventional nozzle. This is due the effect of voltage on the liquid surface tension.

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Characteristic Study of Micro-Nozzles according to the Ratios of Nozzle Expansion and Specific heats in low vacuum condition (저진공상태에서 노즐 팽창비와 비열비에 따른 마이크로 노즐의 특성 연구)

  • Kim, Youn-Ho;Jung, Sung-Chul;Huh, Hwan-Il
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.249-252
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    • 2006
  • We conducted the experiment to analyze characteristics of micro-nozzle using different cold gas under two different nozzle expansion ratios in low vacuum condition. We measured thrust and chamber pressure and mass flow rate under low vacuum condition, and then compared them with those in ambient pressure.

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Design Optimization of Fan-shaped Film Cooling Hole Array on Pressure Side Surface of High Pressure Turbine Nozzle (고압터빈 노즐 압력면에서의 확장 형상 막냉각 홀 배열 최적설계)

  • Lee, Sanga;Rhee, Dong-Ho;Kang, Young-Seok;Kim, Jinuk;Seo, Do-Young;Yee, Kwanjung
    • The KSFM Journal of Fluid Machinery
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    • v.17 no.6
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    • pp.52-58
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    • 2014
  • In the present work, design optimization of film-cooling hole array on the pressure side of high pressure turbine nozzle was conducted. There are four rows of fan-shaped film cooling holes on the nozzle pressure side surface and each row has a straight array of holes in the spanwise direction for baseline model. For design optimization, hole distributions in streamwise and spanwise directions for three rows of holes except first row are parameterized as a 2nd-order shape function. Three-dimensional compressible RANS equations are used for flow and thermal analysis around the nozzle surface and optimization technique using Design of Experiment, Kriging surrogate model and Genetic Algorithm is used. The results shows that averaged adiabatic wall temperature at the whole nozzle surface decreases about 2.7% and averaged film cooling effectiveness at the pressure side of nozzle increased about 8.2%.

A study on the exhaust gas recirculation in a MILD combustion furnace by using a Venturi nozzle (MILD 이용한 배기가스 재순환에 관한 연구)

  • Ha, Ji Soo;Shim, Sung Hoon
    • Journal of Energy Engineering
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    • v.22 no.4
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    • pp.413-419
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    • 2013
  • The present study used the MILD combustor, which has coaxial cylindrical tube. The outside tube of the MILD combustor corresponds to the exhaust gas passage and the inner side tube is the furnace passage. A numerical analysis was accomplished to elucidate the characteristics of exhaust gas entrainment toward the inner furnace with the changes of venturi nozzle geometrical parameters, nozzle position, nozzle gap between high pressure air nozzle and venturi nozzle, and with the change of high pressure nozzle inlet velocity. The entrainment flow rate for the case with the high pressure air nozzle attached at the exhaust gas wall has relatively small change with the change of nozzle gap. That for the case with the high pressure air nozzle exposed to the exhaust gas has monotonically increase with the change of nozzle gap. The flow rate ratio of entrainment flow rate has considerably increase tendency with relatively lower air inlet velocity, on the other hand, that with relatively higher air inlet velocity could be seen relatively small increase.

The Transient Phenomena of Fuel Injection Nozzle for Electronic Control SI Engines (SI 機關용 電子制御 燃料噴射노즐의 過渡的 現象)

  • 김신구;김덕줄;이충원
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.2
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    • pp.308-318
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    • 1988
  • The liquid disintegration and characteristics of atomization through the swirl nozzle is affected by injection pressure and injection time when the liquid is injected intermittently. These transient phenomena are investigated by electronic controlled-fuel injection nozzle. The effect of injection conditions on disintegration of liquid injected through nozzle is observed photographically by using delay circuit. Droplet size of the element of the sample is measured by the liquid immersion sampling technique. SMD of droplets is varied with time and is decreased as the injection pressure increases. As the injection pressure increases, the maximum diameter of droplet and diameter of droplet which has the maximum droplet number decrease. Spray angle is not affected on injection pressure and change of spray angle with time is associated with needle movement.

A Turbulent Bounbary Layer Effect of the De-Laval Nozzle on the Combustion Chamber Pressure (De-Laval 노즐의 난류 경계층 유동이 연소실 압력에 미치는 영향)

  • 장태호;이방업;배주찬
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.5
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    • pp.635-644
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    • 1986
  • A Compuressible turbulent boundary layer effect of the high temperature, accelerating gas flow through the De-Laval nozzle on combustion chamber pressure is numerically investigated. For this purpose, the coupled momentum integral equation and energy integral equation are solved by the Bartz method, and 1/7 power law for both the turbulent boundary layer velocity distribution and temperature distribution is assumed. As far as the boundary layer thicknesses are concerned, we can obtain reasonable solutions even if relatively simple approximations to the skin friction coefficient and stanton number have been used. The effects of nozzle wall cooling and/or mass flow rate on the boundary layer thicknesses and the combustion chamber pressure are studied. Specifically, negative displacement thickness is appeared as the ratio of the nozzle wall temperature to the stagnation temperature of the free stream decreases, and, consequently, it makes the combustion chamber pressure low.

Decrease of Burst Pressure used a Nozzle Closure and Ignition Characteristics for a Gas Generator (가스발생기용 노즐마개 파열압력 저감화에 따른 점화특성)

  • Cha, Hong-Seok;Oh, Seok-Jin;Park, Jae-Beom;Lee, Yeung-Jo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.217-220
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    • 2010
  • This paper presents an achieving method of reducing maximum acceleration for the missile by decrease of burst pressure in a nozzle closure. The relation of notch shape and burst pressure for a nozzle closure is examined by experiment. In the point of maximum acceleration reduction for a missile, an improved nozzle closure effects well compared with that of a reference closure by ground burning test of a gas generator.

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A study on the pintle-tip shapes effect of nozzle flow using cold-flow test (핀틀 형상이 노즐 유동에 미치는 영향에 대한 실험적 연구)

  • Kim, Joung-Keun;Park, Jong-Ho;Lee, Jong-Hoon;Jeon, Min-Kyung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.10
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    • pp.985-991
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    • 2010
  • The objective of this work was to investigate the pintle-tip shape effect on nozzle flow and thrust by cold flow test. When nozzle throat area was decreased by pintle movement, chamber pressure was increased monotonously but thrust was increased differently according to every pintle-tip shape. At the same chamber pressure and nozzle throat area, thrust of convex pintle-tip shape was mostly larger than that of concave one. Nozzle wall pressure distribution and magnitude of pintle-tip load depended on the pintle-tip shape, pintle position and nozzle throat area.

Measurement and Evaluation of Cross-talk Effects in Multi-nozzle Inkjet Head (다중 노즐 잉크젯 헤드의 상호 간섭 측정 및 평가)

  • Kwon, Kye-Si;Kim, Jin-Won
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.1
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    • pp.73-79
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    • 2011
  • Inkjet printhead may have a lot of nozzles to increase productivity as a manufacturing tool. So, the uniformity of jetting performance among a lot of nozzles has been one of the key issues in inkjet technology In this study, we investigated the cross-talk effect which should be reduced for uniform jetting performance among a lot of nozzles. Due to the cross-talk, the jetting performance of a nozzle can be affected when neighboring nozzles are firing. For experimental study, we used commercial inkjet head SE-128 from Dimatix. To understand the cross-talk effect of SE-128 head, we measured the change in jetting speed of a nozzle when neighboring nozzles are jetting. The measured jetting speed was compared to the case of one nozzle jetting. Also, we used laser vibrometer to measure change in pressure wave due to cross-talk. As a result of the cross-talk, the jetting speed can become faster or sometimes slower depending on firing nozzle location. If the all nozzle are jetting, the jetting speed of a nozzle became slower because the pressure wave for jetting is reduced.