• 제목/요약/키워드: Spray jets

검색결과 67건 처리시간 0.022초

초고속 발사체의 액체 저장부 충돌에 의한 초음속 액체 제트의 분무 속도 및 분열 특성 (Spray Angle and Break-up Characteristics of Supersonic Liquid Jets by an Impinging Methods with High Speed Projectile)

  • 이인철;신정환;김희동;구자예
    • 한국가시화정보학회지
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    • 제9권1호
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    • pp.55-60
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    • 2011
  • Pulsed supersonic liquid jets injected into an ambient air are empirically studied by using a high pressure ballistic range system. Ballistic range systems which are configured with high-pressure tube, pump tube, launch tube and liquid storage nozzle. Experimental studies are conducted to use with various impact nozzle geometry. Supersonic liquid jets are generated by an impact of high speed of the projectile. High speed liquid jets are injected with M = 3.2 which pressure is 1.19 GPa. Multiple jets which accompany with shock wave and pressure wave in front of the jet were observed. The shock-wave affects significantly atomization process for each spray droplets. As decreasing orifice diameter, the averaged SMD of spray jets had the decreasing tendency.

공기보조식 (air-assisted) 플래쉬 분무의 분무 각 확대 특성 연구 (Analysis of spray cone angle of air assisted flash atomization)

  • 류태우;김세원;방병열
    • 한국분무공학회지
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    • 제10권1호
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    • pp.1-9
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    • 2005
  • When the water jets heated up to the saturation temperature at a high line pressure are sprayed into a reduced (atmospheric) pressure through an air-assisted nozzle, the jets experience sudden exposure into a reduced pressure, get superheated and produce steam bubbles while atomization processes of jets are taking place. This process is called flash atomization. In this study the flash atomization of superheated water jets assisted by air has been studied. Sprays with flash atomization have been photographed at various water and air flow rates and water superheats. It has been found that the spray angle with flash atomization increases with water superheat and water flow rate but decreases with air flow rate. The degree of change of spray angle has been analyzed and correlated as a function of superheat, air and water flow rates.

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아음속 횡단류로 분사되는 이상유동 제트의 분무특성 (Spray Characteristics of Two-Phase Flow Jets into a Subsonic Crossflow)

  • 이근석;이원구;윤영빈;안규복
    • 한국분무공학회지
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    • 제24권1호
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    • pp.27-34
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    • 2019
  • An experimental study on the spray characteristics of aerated-liquid jets discharged from effervescent injectors to a subsonic crossflow was conducted to investigate effects of a gas to liquid mass ratio (GLR) and a ratio of the orifice length to the diameter (L/d). The present effervescent injectors consist of a plain orifice injector and an aerator. To analyze breakup length and spray trajectory, instantaneous spray images were taken by a high speed camera. As the GLR increased, the spray penetration became higher under the same liquid mass flow rate and the breakup length became shorter due to the bubble expansion or the annular liquid film breakup. To predict the spray trajectory of two-phase flow jets into the crossflow, the homogeneous and the separated flow models were compared.

젤 모사 추진제의 점도 변화에 따른 분무 분열 및 파장 변화 특성 (Breakup Process and Wave Development Characteristics of Gel Propellant Simulants at Various Gelling Agent Contents)

  • 황태진;이인철;김정훈;김도헌;구자예
    • 한국분무공학회지
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    • 제16권3호
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    • pp.140-145
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    • 2011
  • Gelled propellants are non-Newtonian fluids in which the viscosity is a function of the shear rate, and they have a high dynamic shear viscosity which depends on the amount of gelling agent contents. The present study has focused on the breakup process, wave development of ligament and liquid sheets formed by impinging jets with various gelling agent contents. The breakup process of like-on-like doublet impinging jets are experimentally characterized using non-Newtonian liquids. The spray shape with elliptical pattern is distributed in a perpendicular direction to the momentum vectors of the jets. Gelled propellant simulants with high viscosity jets are more stable and produce less pronounced surface waves than low viscosity jets. Gelled propellant simulants from like-on-like doublet impinging jets have the spray shape of closed rim patterns at low pressure. As the injection pressure increased, rimless patterns which were composed of ligament sheets and small droplets emerged due to the effect of the aerodynamic action.

젤 모사 추진제 삼중 충돌 분사 제트의 거시적 분열 특성 연구 (Macroscopic Breakup Characteristics of Water Gel Simulants with Triplet Impinging Spray Jet)

  • 황태진;이인철;구자예
    • 한국분무공학회지
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    • 제15권3호
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    • pp.109-114
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    • 2010
  • The implementation of gelled propellants systems offers high performance, energy management of liquid propulsion, storability, and high density impulse of solid propulsion. The present study focused on the macroscopic spray characteristics of liquid sheets formed by triplet impinging jets of non-Newtonian liquids which are mixed by Carbopol 941 0.5%wt. The results are compared to experiments conducted on spray images which formed by triplet impinging jets concerning with airassist effect at center orifice. When gel propellants are injected by doublet impinging jets at low pressure and high pressure, closed rim pattern shape appeared by polymeric effect from molecular force and showed inactive atomization characteristics, because of extensional viscosity related by restriction of atomization process and breakup time delay of turbulence transition. As increasing mass flow rate of the air(increasing GAR), spray breakup level is also increased.

충돌 제트로 형성되는 분무의 속도 특성에 대한 연구 (A Study on the Velocity Characteristics of the Spray Formed by Two Impinging Jets)

  • 추연준;오대진;강보선
    • 한국분무공학회지
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    • 제6권2호
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    • pp.1-8
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    • 2001
  • In this study, the velocity characteristics of liquid elements formed by two impinging jets is analysed using double pulse image capturing technique. For the droplets formed by low speed impinging jets, the droplet velocities are higher with smaller azimuthal and impingement angle. The maximum droplet velocities are about 25 % lower than jet velocity. With an increase of azimuthal angle, the shedding angles increases but remains lower than azimuthal angle. The velocities of ligaments formed by high speed impinging jets gradually decreases with an increase of azimuthal angle. The maximum ligament velocities are about 40% lower than jet velocity. Higher impingement angles produce lower ligament velocities. The shedding angles of ligament almost increases with the same value of azimuthal angle, which implies that the moving direction of ligaments is radial from the origin as the impingement point.

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발사체 충격 방식을 사용한 초음속 액체 제트의 과도 분무 형상에 관한 연구 (Transient Spray Structures of Supersonic Liquid Jet Injected by Projectile Impact Systems)

  • 신정환;이인철;김희동;구자예
    • 한국분무공학회지
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    • 제17권2호
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    • pp.86-93
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    • 2012
  • The effects of projectile impact system on the transient spray characteristic which is supersonic liquid tip velocity were studied by experimentally. Supersonic liquid jets were generated by impact of a high speed projectile driven by a Two-stage light gas gun. A high speed camera and schlieren optical system were used to capture the spray structures of the supersonic liquid jets. In a case of nozzle assembly Type-A, expansion gases accelerate a projectile which has a mass of 6 grams from 250 m/s at the exit of the launch tube. Accelerated projectile collides with the liquid storage part, then supersonic liquid jets are injected with instantaneous spray tip velocity from 617.78 m/s to 982.54 m/s with various nozzle L/d. However, In a case of nozzle assembly Type-B which has a heavier projectile (60 grams) and lower impact velocity (182 m/s), an impact pressure was decreased. Thus the liquid jet injected at 210 m/s of the maximum velocity did not penetrate a shock wave and fast break-up was occurred. Pulsed injection of liquid column generated second shock wave and multiple shock wave.

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

  • 송윤호;안규복
    • 한국분무공학회지
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    • 제23권1호
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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.

노즐 형상비에 따른 고압 분사류의 유동특성에 관한 실험적 연구 (Experimental Study on the Flow Characteristics of High Pressurized Jets Depending upon Aspect Ratio)

  • 남궁정환;이상진;김규철;이삼구;노병준
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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    • pp.233-236
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    • 2002
  • The high-pressurized spray nozzle is used f3r special washing and cutting with strong impact force. The performance of this nozzle, which focused on spray penetration and radial dispersion, was mainly investigated to maximize the momentum and minimize the flow loss. Hence, our experimental research was conducted by changing the aspect ratio ranging from 0 to 3 with nozzle outlet of 1.1. The spray trajectory far high-pressurized water was experimentally investigated using PDPA diagnostics, which was available at spray downstream region. As the spray at upstream near the nozzle exit did not show the improved disintegration. The results showed empirical correlation with regard to non-dimensional axial velocity distribution, spray penetration, and radial spreading rate with photographic visualization.

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충돌제트로 생성되는 분무의 특성에 관한 연구 (A Study on the Characteristics of the Spray Produced by Two Impinging Jets)

  • 강보선
    • 한국분무공학회지
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    • 제2권4호
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    • pp.22-28
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    • 1997
  • In this paper an experimental study of a spray created by two impinging jets is presented utilizing a novel two-reference-beam double-pulse holographic technique. Visualization of the overall spray pattern as well as measurements on the size and velocity of the droplets were performed with the special emphasis on the effect of physical properties of liquids. The overall spray pattern clearly revealed the inherent wave nature In the disintegration process of this type of atomization. The structure of liquid elements near the impingement point is indicative of the mechanisms of the disintegration process. Surface tension plays an important role in the droplet size without any noticeable effect on the spray pattern, whereas viscosity affects the structure without any significant effect on the droplet sire. The droplet velocities were not affected by liquid properties.

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