• Title, Summary, Keyword: Nozzle Pressure

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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
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    • v.17 no.4
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    • pp.617-625
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    • 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.

The Enhacned Atomization of Single Hole Nozzle by Cavitation at The Low Pressure Injection (저압 분사시 캐비테이션에 의한 단공 노즐의 미립화 향상)

  • Son, Jong-Won;Cha, Keun-Jong;Kim, Duck-Jool
    • Proceedings of the KSME Conference
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    • pp.952-957
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    • 2001
  • The objectives of this investigation were to obtain an excellent spray by cavitation under the low injection pressure. When cavitation occurs in the nozzle hole, the atomization of the liquid jet enhanced considerably. In this experiments, a acrylic nozzle made the gap and installed the bypass in the nozzle hole was used to enhance the atomization of the liquid jet at the low injection pressure. The liquid flow in the nozzle hole was photographed by a transmitted light using a micro flash. The spray angle was measured macroscope images of PMAS and the Sauter mean diameter was measured PDA system. To measure the pressure of the nozzle hole, pressure transducer was used. The results of this study indicated that enhanced atomization of the liquid jet at the low injection pressure was obtained by making the gap and installing the bypass at the single hole nozzle.

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The Influence of the Diffuser Divergence Angle on the Critical Pressure of a Critical Nozzle (디퓨저 확대각이 임계노즐의 임계압력비에 미치는 영향)

  • Kim Jae Hyung;Kim Heuy Dong;Park Kyung Am
    • Proceedings of the KSME Conference
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    • pp.131-134
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    • 2002
  • Compressible gas flow through a convergent-divergent nozzle is choked at the nozzle throat under a certain critical pressure ratio, and then being no longer dependent on the pressure change in the downstream flow field. In practical, the flow field at the divergent part of the critical nozzle can affect the effective critical pressure ratio. In order to investigate details of flow field through a critical nozzle, the present study solves the axisymmetric, compressible, Wavier-Stokes equations. The diameter of the nozzle throat is D=8.26mm and the half angle of the diffuser is changed between $2^{\circ}\;and\;10^{\circ}$ Computational results are compared with the previous experimental ones. The results obtained show that the divergence angle is significantly influences the critical pressure ratio and the present computations predict the experimented discharge coefficient and critical pressure ratio with a good accuracy. It is also found that a nozzle with the half angle of $4^{\circ}$ nearly predicts the theoretical critical pressure ratio.

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Operating Performance of Solenoid Valve and Nozzle Sets for Target Selectable Sprayers (이동형 국소 분무장치용 전자 밸브와 노즐 조합 작동특성)

  • Suh, S.R.;Kim, H.O.;Kim, Y.T.;Choi, Y.S.;Yoo, S.N.
    • Journal of Biosystems Engineering
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    • v.31 no.1
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    • pp.39-45
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    • 2006
  • Fundamental informations on performance of sets of solenoid valve and nozzle were necessary to develop a target selectable spraying system. The experiments were performed for the sets of solenoid valves and flat spraying nozzles at 3 levels of the operating pressures, and the obtained results are as follows; Rise time of the system pressure to reach up to 90% of the operating pressure after the valve turned was affected by nozzle size and operating pressure. Maximum overshoot of the system pressure was about 170% not affected by the sets of valve and nozzle and operating pressure. The system pressure after its settle down within 5% of the set pressure showed good uniformity in any condition of the experiment as less as 2.3% of its coefficient of variation. Time requirement to lower the system pressure down to 50% after the valve power turned off was affected by valve and nozzle set and operating pressure.

An Experimental Study on Flow in the Nozzle of a Radial Turbine (구심터빈의 노즐 내부 유동에 대한 시험 연구)

  • Kang, Jeong-Seek;Lim, Byeung-Jun;Ahn, Iee-Ki
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.1
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    • pp.35-41
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    • 2010
  • Experimental study on the flow field inside the nozzle for radial turbine was performed. At design point, the pressure is high and the Mach number is low at the pressure side of the nozzle inlet semi-vaneless space as the flow turns through the nozzle vanes. As the flow accelerates through the nozzle passage to the throat the pressure level at the pressure and suction sides becomes similar. The flow continued accelerating from the throat to the inlet of turbine wheel and the pressure field became uniform in the circumferential direction in the vaneless space. In high expansion ratio condition, strong favorable pressure gradient band region occurred just after the throat in the semi-vaneless space in the circumferential direction and the pressure became uniform in the circumferential direction after this band. In low expansion ratio condition, core flow acceleration is dominant after the throat and this non-uniform pressure field reached to the inlet of turbine wheel.

Influnce of Cutting Pressure on Laser Cut Quality (Pressure Distribution of Cutting Gas) (레이저 절단품질에 미치는 절단압력의 영향 (1) (절단가스의 압력분포))

  • Yang, Yeong-Su;Na, Seok-Ju;Koo, Hyeong-Mo;Kim, Tae-Gyun
    • Journal of the Korean Society for Precision Engineering
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    • v.4 no.4
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    • pp.84-92
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    • 1987
  • To investigate the influence of the cutting pressure on the laser cutting quality, an expermental facility was constructed which can measure the cutting pressure distribution for various cutting conditions. Flow visualization was performed using the Schlieren photography and the pressure acting on the workpiece surface was measured, corresponding to the important process variables such as the kind of assist gas, nozzle pressure, distance between the nozzle exit and the workpiece surface, and the presence of the secondary nozzle. The cutting pressure acting on the workpiece was largely influenced by the nozzle pressure and nozzle-workpiece distance. The secondary nozzle which is used to raise the effective working pressure had its obvious role only when the angle between it and the main nozzle was small and when the distance between the nozzle exit and the workpiece surface was large.

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A Study on the Optimum Shape of High-Pressure Injection Nozzle (고압 분사노즐의 최적형상에 관한 연구)

  • 이종선;김형철
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.2
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    • pp.37-43
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    • 2003
  • This study makes to flow analysis of computational fluid dynamics(CFD) according to the basic theory of turbulent flow regarding high-pressure injection nozzle. It also makes structural analysis to find out the structural validity of the optimum shape of high-pressure injection nozzle. It divides to two areas such as plunger areas and high-pressure injection nozzle area including plunger.

Effect of Suction Nozzle Modification on the Performance and Aero-acoustic Noise of a Vacuum Cleaner

  • Park, Cheol-Woo;Lee, Sang-Ik;Lee, Sang-Joon
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1648-1660
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    • 2004
  • The suction nozzle of a vacuum cleaner was modified to enhance the power performance and to reduce the airflow-induced acoustic noise. The suction power efficiencies of the vacuum cleaner were measured for various nozzles; (1) original nozzle, (2) original nozzle with modified trench height, (3) original nozzle with modified connecting chamber, and (4) a combination of (2) and (3). In addition, the suction pressure and sound pressure level around the suction nozzle were measured to validate the reduction of acoustic noise. The power efficiency and mean suction pressure increased when the trench height of the suction nozzle was increased. This was attributed to the suppression of the flow separation in the suction channel. Modification of the connecting chamber in the original nozzle, which had an abrupt contraction from a rectangular chamber into a circular pipe, into a smooth converging contraction substantially improved the suction flow into the connecting pipe. When both modifications were applied simultaneously, the resulting suction nozzle was more effective from the viewpoints of aerodynamic power increase and sound pressure level reduction.

Thrust modulation performance analysis of pintle-nozzle motor (핀틀 노즐형 로켓 모타의 추력 조절 성능에 관한 연구)

  • Kim, Joung-Keun;Park, Jong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.4
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    • pp.392-398
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    • 2009
  • Theoretical thrust equations for the diverse nozzle expansion condition were derived. By using the obtained thrust equations, parametric studies were carried out to estimate the effect of pressure exponent, minimum operation pressure, ambient pressure and extinguishment pressure on thrust modulation performance in pintle-nozzle solid rocket motors. Analysis results showed that thrust turndown ratio can be easily attained by small nozzle-throat area variation at high pressure exponent, low minimum operation pressure, high ambient pressure and high extinguishment pressure condition. At those conditions, the highest chamber pressure to obtain the intended thrust turndown ratio can be minimized.

Spray Characteristics of Air-assisted Vortex Nozzle at Low Pressure Condition (공기보조식 와류 노즐의 저압 분무특성)

  • Kim, Woojin;Subedi, Bimal;Choi, Jang-Soo
    • Journal of ILASS-Korea
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    • v.20 no.2
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    • pp.82-87
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    • 2015
  • A nozzle with vortex generator was used to develop the low pressure nozzle with high atomization performance and the nozzle atomized the liquid by centrifugal shear forces. In order to analyze the atomization characteristics, a shadowgraphy method was used and the measurement of droplet size was performed by using laser diffraction analyzer. The liquid injection pressure was fixed as 0.03 bar which is very low pressure and the gas injection pressures were changed from 0 bar to 2.0 bar. As a result, the breakup was achieved at the air injection pressure of 0.25 bar and over. The nozzle with the orifice diameter of 0.4 mm and the orifice gap of 0.25 mm presented small droplet diameters under 50 at the air injection pressure of 0.75 bar.