• 제목/요약/키워드: Water atomization

검색결과 191건 처리시간 0.022초

핀틀 인젝터를 사용한 젤 추진제 분무 특성 연구 (Characteristics of Gel Propellant Spray from a Pintle Injector)

  • 이건웅;송우석;황주현;황용석;구자예
    • 한국분무공학회지
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    • 제24권2호
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    • pp.82-88
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    • 2019
  • Shear coaxial injectors were commonly used in rocket engine combustor. They showed good combustion performance. However it is not easy to control the thrust. Pintle injectors were not as popular as the coaxial injectors so far, they have a great advantage over the coaxial injectors. That is, it is relatively easy to control the thrust. Spray characteristics of gel type propellant from movable sleeve pintle injector were investigated. Water with 0.05% of Carbopol 940 was used as gel simulant instead of kerosene gel combined with Thixarol ST for academic purpose. Experiments were performed in various temperature, pressure and pintle opening condition. The results were compared with neat liquid spray. It is also verified that the capabilites of the injector by adjusting the pintle opening.

상압조건에서 1-부탄올 젤 연료액적의 연소특성 (Combustion Characteristics of a 1-Butanol Gel Fuel Droplet in Atmospheric Pressure Condition)

  • 남시욱;김혜민
    • 한국분무공학회지
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    • 제26권3호
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    • pp.120-126
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    • 2021
  • Combustion characteristics of a 1-butanol gel fuel were studied in atmospheric pressure condition. The butanol gel fuel was manufactured by adding hydroxypropyl-methyl cellulose (HPMC) as a gellant and the effect of the gellant concentration was observed. The combustion process of a single butanol gel droplet was divided into 3 stages including droplet heating, microexplosion, and gellant combustion. The flame was distorted compared to butanol + water mixture because of micro-explosion during the combustion. Increase of gellant concentration delayed the droplet ignition, but the combustion rate was improved due to the mass ejection during the micro-explosion.

인젝터 압력이 단공노즐 감압비등 분무에 미치는 영향 (Effect of Injection Pressure on the Flash Boiling Spray from Simple Orifice Nozzle)

  • 이현창;차현우;강동현
    • 한국분무공학회지
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    • 제27권1호
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    • pp.42-49
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    • 2022
  • Flash boiling occurs in a couple of modern engineering systems and understanding its mechanism is important. In this experimental study, discharge coefficient of flash boiling spray from simple orifice nozzle was measured, and backlight imaging was acquired at injection pressure to 6.0 bar and temperature to 163℃ for the purpose. Pressurized water by pump was used for working fluid and was heated by electric heater and ejected through simple orifice nozzle diameter of 0.5 mm. High speed camera with long distance microscope was used for backlight imaging in two FoV having magnification of 3.3 and 0.64. The decrease of discharge coefficient according to degree of superheating and evolution of flash boiling spray imaged at various pressure and temperature were explained by the pressure field inside the injector.

벽 충돌 제트로 생성되는 액막의 두께 분포 특성 연구 (A Study on the Thickness Characteristics of the Liquid Sheet Formed by an Impinging Jet Onto a Wall)

  • 이진성;이태영;조정민;강보선
    • 한국분무공학회지
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    • 제28권2호
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    • pp.68-74
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    • 2023
  • In this study, the thickness of the liquid sheet formed by a low speed impinging jet onto a wall was measured by the direct contact method. The spatial distribution characteristics of the sheet thickness in the radial and circumferential directions, and the effects of jet velocity and liquid viscosity were analyzed. The measurement results were compared with the theoretical predictions for two impinging jets. The wavy surface was observed for low viscosity water, but not for high viscosity glycerol solutions. The sheet thickness decreased as the circumferential angle or the distance from the impinging point increased. The sheet thickness increased as the liquid viscosity increased. Comparison with the theoretical predictions showed some differences from the measurement results.

전단동축형 분사기의 유량계수에 대한 형상학적 변수들의 영향 (Effect of Geometrical Parameters on Discharge Coefficients of a Shear Coaxial Injector)

  • 안종현;이근석;안규복
    • 한국분무공학회지
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    • 제25권3호
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    • pp.95-102
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    • 2020
  • Six shear coaxial injectors for a 3 tonf-class liquid rocket engine using oxygen and methane as propellants were designed and manufactured by considering geometric design parameters such as a recess length and a taper angle. Cold-flow tests on the injectors were performed using water and air as simulants. By changing the water mass flow rate and air mass flow rate, the injection pressure drop under single-injection and bi-injection was measured. The discharge coefficients through the injector oxidizer-side and fuel-side were calculated and the discharge coefficient ratio between bi-injection and single-injection was obtained. Under single-injection, the recess served to reduce the injection pressure drop on the injector fuel-side. For the injectors without recess, the discharge coefficients under bi-injection were almost the same as those under single-injection. However, for the injectors with recess, the taper angle and bi-injection had a significant effect on the discharge coefficient.

저압 TBI용 분사밸브의 분무특성에 관한 연구 (I) (Study on the Spray Characteristics in TBI Injector with Low Pressure)

  • 전흥신;임종한;이택희
    • 대한기계학회논문집
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    • 제17권12호
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    • pp.3179-3186
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    • 1993
  • The study on the spray characteristics of TBI(Throttle Body Injection) injector has been carried out in this paper. The objective of this study is to improve the performance of TBI injector. The increase in the injection pressure and the utilization of assisted air are considered. The spray patten of TBI injector take the hollow-cone shape with $60^{\circ}~70^{\circ}$ spray angle regardless of injection pressure and injection pulse width. SAMD(Sauter Mean Diameter) of water in TBI injector are 510-$550{\mu}m$ and 310-$370{\mu}m$ respectively when injection pressures are $0.75 kgf/cm^{2}$ and $2.8 kgf/cm^{2}$. Then SMD of gasoline is estimated 380~$410{\mu}m$ and 230~$280{\mu}m$ respectively. The improvement of spray characteristics in TBI injector can be obtained with assisted air. If $W_{A}/W_{L}$ was over 0.2, SMD of water can be made under $50{\mu}m$.

Experimental Investigation of Coupling Effects between Particle Size and Temperature on the Thermal Conductivity of Alumina Nanofluids

  • Lee, Ji-Hwan;Jang, Seok Pil;Lee, Seung-Hyun;Park, Yong-Jun;Kim, Dong Jin;Koo, Jaye
    • 한국분무공학회지
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    • 제19권4호
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    • pp.174-181
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    • 2014
  • This study investigates the effects of nanoparticle size and temperature on the thermal conductivity enhancement of water-based alumina ($Al_2O_3$) nanofluids, using the centrifuging method and relative centrifugal forces of differing magnitude to produce nanofluids of three different particles without involving any dispersants or surfactants. We determined the coupling dependency in thermal conductivity enhancement relative to nanoparticle size and temperature of the alumina nanofluids and also experimentally showed that the effect of temperature on thermal conductivity is strongly dependent on nanoparticle size. Also, our experimental data presented that the effective medium theory models such as the Maxwell model and Hasselman and Johnson model are not sufficient to explain the thermal conductivity of nanofluids since they cannot account for the temperature- and size-dependent nature of water-based alumina nanofluids.

Matrix Modification for Graphite Furnace Atomic Absorption Spectrophotometric Determination of Volatile Elements(III) Trace Bismuth

  • Kim, Young-Sang;Choi, Jong-Moon;Kim, Young-Man
    • 분석과학
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    • 제8권4호
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    • pp.435-442
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    • 1995
  • A matrix modification was studied for the determination of trace bismuth in water samples by graphite furnace atomic absorption spectrophotometry. The type and quantity of modifiers as well as the use of auxiliary modifiers were investigated to realize the efficient modification. Palladium was chosen as a single modifier. By the addition of palladium($5{\mu}g/mL$) to 100 ng/mL bismuth solution, the temperatures could be raised from $500^{\circ}C$ to $1,300^{\circ}C$ for the charring and from $2,000^{\circ}C$ to $2,200^{\circ}C$ for the atomization as well as the sensitivity and reproducibility were improved. The absorbance of bismuth was maximum and not changed in the range of Pd $3-25{\mu}g/mL$. And several materials were examined as an auxiliary modifier. The mixed solution of $1{\mu}g/mL$ palladium and $200{\mu}g/mL$ nickel have raised the temperatures as with $5{\mu}g/mL$ palladium only. The maximum absorbance of bismuth was shown in the nickel concentration range of $100-300{\mu}g/mL$ in $1{\mu}g/mL$ palladium modified system. With such optimum conditions, the trace amount of bismuth in several water samples could be determined by a calibration curve method, and good recoveries were also obtained.

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소수성 텍스쳐 표면에 충돌한 단일 액적의 퍼짐 및 고착 특성 (Spreading and Deposition Characteristics of a Water Droplet Impacting on Hydrophobic Textured Surfaces)

  • 이재봉;문주현;이성혁
    • 한국분무공학회지
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    • 제17권1호
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    • pp.14-19
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    • 2012
  • The present study conducts experimental investigation on spreading and deposition characteristics of a $4.3{\mu}l$ de-ionized (DI) water droplet impacting upon aluminum (Al 6061) flat and textured surfaces. The micro-textured surface consisted the micro-hole arrays (hole diameter: $125{\mu}m$, hole depth: $125{\mu}m$) fabricated by the conventional micro-computer numerical control (${\mu}$-CNC) milling machine process. We examined the surface effect of texture area fraction ${\varphi}_s$ ranging from 0 to 0.57 and impact velocity of droplet ranging from 0.40 m/s to 1.45 m/s on spreading and deposition characteristics from captured images. We used a high-speed camera to capture sequential images for investigate spreading characteristics and the image sensor to capture image of final equilibrium deposition droplet for analyze spreading diameter and contact angle. We found that the deposition droplet on textured surfaces have different wetting states. When the impact velocity is low, the non-wetting state partially exists, whereas over 0.64 m/s of impact velocity, totally wetting state is more prominent due to the increase kinetic energy of impinging droplet.

분사압력 변이에 따른 70 N급 액체로켓엔진 인젝터의 분무성능특성 (Effects of Injection Pressure on the Spray Performance Characteristics of the 70 N-class Liquid-rocket Engine Injector)

  • 정훈;김종현;김정수;박정;이재원
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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    • pp.180-186
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    • 2012
  • 본 연구팀에서 개발 중인 70 N급 액체로켓엔진의 설계성능 검증에 앞서 요소부품인 비충돌형 인젝터에 대한 인수시험 및 수류시험을 수행하였다. 인젝터 오리피스 인수시험 결과 미시적 관점에서의 가공오차가 확인되었으며, 그로 인해 각각의 오리피스에서 발현되는 분무거동에 차이를 보였다. 순간 분무이미지를 통해 액주(혹은 액적) 표면에 나타나는 파동과 유동의 주기적 흘림현상을 관찰하였다.

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