• Title/Summary/Keyword: Hydraulic Flip

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Effects of Orifice Internal Flow on Transverse Injection into Subsonic Crossflows (아음속 유동장에 수직분사시 오리피스 내부유동 효과에 대한 연구)

  • 김정훈;안규복;윤영빈
    • Journal of the Korean Society of Propulsion Engineers
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    • v.7 no.1
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    • pp.28-39
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    • 2003
  • Effects of the orifice internal flow such as cavitation and hydraulic flip on transverse injection into subsonic crossflows have been studied. The liquid column breakup length and the liquid column trajectory were measured by changing the orifice diameter (d), the orifice length/orifice diameter (L/d), the injection pressure and the shapes (sharp and round) of orifice entrance, and were compared with previous results. It is found that cavitation bubbles, which occur inside the sharp-edged orifice, make the liquid jet very turbulent and especially in the orifices with L/d = 5 hydraulic flip appear as cavitation bubbles are emitted from the orifice. The breakup length is shorter as cavitation bubbles grows and hydraulic flip appears. However, the liquid column trajectories normalized by the effective diameter and the effective momentum ratio have a similar tendency irrespective of cavitation and hydraulic flip.

Effects of Orifice Internal Flow on Transverse Injection into Subsonic Crossflows: Cavitation and Hydraulic Flip (오리피스 내부 유동조건에 따른 수직분사제트의 분열특성에 대한 연구)

  • 안규복;김정훈;윤영빈
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2003.05a
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    • pp.72-75
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    • 2003
  • In this research, we focused on the effects of the orifice internal flow such as cavitation and hydraulic flip. The breakup characteristics such as the breakup length and trajectory were measured by changing the orifice diameter (d), the orifice length/orifice diameter (L/d), the injection pressure and the shapes (sharp and round) of orifice entrance to provide a lot of conditions of the orifice internal flow. It is found that cavitation bubbles that occur inside the sharp-edged orifice make the liquid jet ejecting from the orifice turbulent. In the orifices (L/d = 5), the hydraulic flip phenomenon is shown when the injection pressure is high. In case cavitation occurs it breaks up more earlier than that in case of non-cavitation. In case hydraulic flip occurs, since the area of the liquid jet becomes small, the breakup length is also small as that in case of cavitation. But the liquid column trajectories have a similar tendency irrespective of cavitation.

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Breakup Lengths of Circular and Elliptical Liquid Jets in a Crossflow (횡단류 유동 내 원형 및 타원형 액체제트의 분열길이)

  • Song, Yoonho;Ahn, Kyubok
    • Journal of ILASS-Korea
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    • v.23 no.1
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    • pp.9-15
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    • 2018
  • Breakup lengths of circular and elliptical liquid jets in a subsonic crossflow were experimentally studied. Two circular-shaped and four elliptical-shaped plain-orifice injectors, which had different aspect ratios and orifice length to diameter ratios, were used to provide various liquid jet conditions such as steady, cavitation, and hydraulic flip. By varying the injection pressure drop from 1 bar to 6 bar, spray images were taken using a shadowgraph technique. Breakup lengths were measured and analyzed. As the aspect ratio in orifices increased, liquid column breakup lengths normalized by the equivalent diameter were reduced irrespectively of the switching of the major or minor axis to the crossflow. It was also found that when hydraulic flip developed inside the orifice, x-directional breakup lengths more decreased for both circular and elliptical liquid jets.

Experimental Study of Discharge Coefficient and Cavitation for Different Nozzle Geometries (노즐 오리피스 형상에 따른 Discharge Coefficient와 Cavitation에 관한 실험적 연구)

  • Kim, Sung-Ryoul;Ku, Kun-Woo;Hong, Jung-Goo;Lee, Choong-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.10
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    • pp.933-939
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    • 2010
  • The purpose of this study is to investigate the generation and development of cavitation in circular and elliptical nozzles. In order to investigate the influence of cavitation, the experiment was conducted with a set of elliptical nozzles that had the same cross-sectional area, different orifice aspect ratios (a/b). Each nozzle was made of acrylic so that visualization was possible. With the injection pressure, the internal flow of the nozzle was classified into the no-cavitation, cavitation, and hydraulic-flip regions. Regardless of the nozzle geometry, with the injection pressure, the flow rate in the no-cavitation and cavitation regions increased and the discharge coefficient decreased. However, the flow rate was constant in the hydraulic-flip region. In the elliptical nozzles, the generation and development of cavitation occurred at higher cavitation number than that in the case of a circular nozzle.

EXPERIMENTAL INVESTIGATION OF PRESSURE FLUCTUATIONS ON THE BED OF FLIP BUCKET SPILLWAYS

  • KAVIANPOUR M.R.;POURHASAN M.A.
    • Proceedings of the Korea Water Resources Association Conference
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    • 2005.09a
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    • pp.590-591
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    • 2005
  • Hydrodynamic pressure fluctuations and their roles on the design of hydraulic structures has been the subject of many investigations. The studies showed that turbulent pressure fluctuations may cause serious damages to hydraulic structures. In case of high velocity flows, separation of flow from the boundary also causes the local pressure to drop and as a result, the resultant pressure fluctuations may trigger cavitation. Sever hydrodynamic pressures are also associated with the vibration of structures. Therefore, in this work, experiments were performed to determine the intensity of pressure fluctuations and their distribution along the bed of a ski-jump flip bucket. Experiments were completed on a physical model at the Institution of Water Research of Iran. The results consist of the statistical characteristics of pressure fluctuations, its maximum, minimum, and r.m.s values along the bed of the bucket. The spectral analysis of pressure fluctuations which is useful for the instability analysis of such structures is also provided. It is hoped that the present results will help the designer of such structures.

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An Experimental Study on Droplet Size Characteristics of Liquid Jets in Subsonic Crossflow (수직분사제트에서 액적크기특성에 대한 실험적 연구)

  • Kim, Min-Ki;Song, Jin-Kwan;Kim, Jin-Ki;Yoon, Young-Bin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.11a
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    • pp.59-63
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    • 2006
  • A direct photograph measurement technique was used to determine the spatial distribution of the spray droplet diameter in subsonic crossflow and it also obtain that SMD distribution by using PLLIF technique. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of this research are getting a droplet distribution and drop size measurement of normal flow and compare with the other flow effects. Although the study showed visually that drop size were spatially dependent of Air-stream velocity, fuel injection velocity, and normalized distance from the injector exit length.(x/d, y/d) There are also difference characteristics between cavitation, hydraulic flip and the normal flow.

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An Experimental Study on Droplet Size Characteristics of Liquid Jets in Subsonic Crossflow (아음속 수직분사제트에서 액적크기 특성에 대한 실험적 연구)

  • Kim, Min-Ki;Song, Jin-Kwan;Kim, Jin-Ki;Hwang, Yong-Seok;Yoon, Young-Bin
    • Journal of ILASS-Korea
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    • v.12 no.2
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    • pp.115-122
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    • 2007
  • The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomize. internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD (Sauter Mean Diameters) distribution by using Planar Liquid Laser Induced Fluorescence technique. The objectives of this research are get a droplet distributions and drop size measurements of each condition and compare with the other flow effects. As the result, This research has been showned that droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects, and normalized distance from the injector exit length(x/d, y/d). There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

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An Experimental Study on Angled Injection and Droplet Size Characteristics of Liquid Jets in Subsonic Crossflow

  • Kim, Min-Ki;Song, Jin-Kwan;Hwang, Jeong-Jae;Yoon, Young-Bin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.486-491
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    • 2008
  • The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomizer internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD(Sauter Mean Diameters) distribution by using PLLIF(Planar Liquid Laser Induced Fluorescence) technique. The objectives of this research are getting a droplet distribution and drop size measurement of each condition and compare with the other flows effect. As the result, This research have been showed the droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects and normalized distance from the injector exit length.(x/d, y/d)There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

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An Experimental Study on Compressibility Effect in Sloshing Phenomenon (압축성이 슬로싱 현상에 미치는 영향에 관한 실험적 연구)

  • Park, Jun-Soo;Kim, Hyun-Yi;Lee, Ki-Hyun;Kwon, Sun-Hong;Jeon, Soo-Sung;Jung, Byoung-Hoon
    • Journal of Ocean Engineering and Technology
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    • v.23 no.4
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    • pp.12-18
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    • 2009
  • The present study focused on the compressibility of partially filled fluids in a sloshing tank. Filling ratios ranging from 18% to 26% were used to find compressible impact on a vertical wall. The model test was for 1/25 scale of a 138 K LNGC cargo tank. To investigate the two dimensional phenomenon of sloshing, a longitudinal slice model was tested. A high speed camera was used to capture the flow field, as well as the air pocket deformation. The pressure time history synchronized with the video images revealed the entire compressible process. Three typical impact phenomena were observed: hydraulic jump, flip through, and plunging breaker. In particular, the pressure time history and flow pattern details for flip through and plunging breaker are presented.

Spray Plume Characteristics of Liquid Jets in Subsonic Crossflows (수직분사제트의 액적영역 분무특성에 대한 연구)

  • Song, Jin-Kwan;Ahn, Kyu-Bok;Oh, Jeong-Seog;Yoon, Young-Bin
    • Journal of ILASS-Korea
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    • v.11 no.2
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    • pp.113-120
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    • 2006
  • The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic cross flows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory and width of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It's also found that the injector internal turbulence influences the spray plume characteristics significantly.

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