• 제목/요약/키워드: Nozzle Pressure

검색결과 1,464건 처리시간 0.03초

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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    • 제17권4호
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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.

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

  • 손종원;차건종;김덕줄
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집B
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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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임계노즐에서 발생하는 비정상유동에 관한 연구 (Study of the Unsteady Gas Flow in a Critical Nozzle)

  • 김재형;김희동;박경암
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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    • pp.337-345
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    • 2002
  • The present study addresses a computational result of unsteady gas flow through a critical nozzle. The axisymmetric, unsteady, compressible, Wavier-Stokes equations are solved using a finite volume method that makes use of the second order upwind scheme for spatial derivatives and the multi-stage Runge-Kutta integral scheme for time derivatives. The steady solutions of the governing equation system are validated with the previous experimental data to ensure that the present computational method is valid to predict the critical nozzle flows. In order to simulate the effects of back pressure fluctuations on the critical nozzle flows, an excited pressure oscillation with an amplitude and frequency is assumed downstream of the exit of the critical nozzle. The results obtained show that for low Reynolds numbers, the unsteady effects of the pressure fluctuations can propagate upstream of the throat of critical nozzle, and thus giving rise to the applicable fluctuations in mass flow rate through the critical nozzle, while for high Reynolds numbers, the pressure signals occurring at the exit of the critical nozzle do not propagate upstream beyond the nozzle throat. For very low Reynolds number, it is found that the sonic line near the throat of the critical nozzle remarkably fluctuateswith time, providing an important mechanism for pressure signals to propagate upstream of the nozzle throat, even in choked flow conditions. The present study is the first investigation to clarify the unsteady effects on the critical nozzle flows.

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

  • 김재형;김희동;박경암
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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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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구심터빈의 노즐 내부 유동에 대한 시험 연구 (An Experimental Study on Flow in the Nozzle of a Radial Turbine)

  • 강정식;임병준;안이기
    • 한국유체기계학회 논문집
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    • 제13권1호
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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.

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

  • 양영수;나석주;구형모;김태균
    • 한국정밀공학회지
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    • 제4권4호
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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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고압 분사노즐의 최적형상에 관한 연구 (A Study on the Optimum Shape of High-Pressure Injection Nozzle)

  • 이종선;김형철
    • 한국공작기계학회논문집
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    • 제12권2호
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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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    • 제18권9호
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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.

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

  • 김중근;박종호
    • 한국항공우주학회지
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    • 제37권4호
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    • pp.392-398
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    • 2009
  • 노즐의 팽창 조건에 따라 적용할 수 있는 이론적인 추력을 구하고 구해진 추력식을 이용하여 고체 추진기관의 추력을 조절하는 핀틀 추진기관의 설계변수, 즉 압력지수, 최소 작동압력, 대기압, 소화압력이 추력 조절 성능에 미치는 영향을 분석하였다. 분석결과 압력지수가 클수록, 최소 작동압력이 낮을수록, 대기압이 높을수록, 그리고 소화압력이 높을수록 핀틀로 노즐목 면적 크기를 조금만 조절하여도 낮은 연소관 압력 조절 범위에서 충분히 원하는 추력비를 얻을 수 있음을 확인하였다.

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

  • 김우진;비멀;최장수
    • 한국분무공학회지
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    • 제20권2호
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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.