• Title/Summary/Keyword: Inclined Spray Angle

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Experimental Study on Film Boiling Heat Transfer of Spray Cooling for Inclined heat transfer Surface (경사면에서의 분무냉각 막비등 열전달에 관한 실험적 연구)

  • Kim, Yeung-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.1
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    • pp.33-39
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    • 2010
  • The film boiling heat transfer was experimentally investigated for the water sprays impacting on an inclined hot surface. Full cone spray nozzles were employed for the spray cooling experiment, and experiments were made for different inclination angles of $\theta=0^{\circ}$, $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$. The experimental results show that, in the downstream region of the inclined hot surface, increasing the inclination angle increases the local heat flux slowly because of increasing the number of rebound droplets. However, the inclination angle of heat transfer surface had no remarkable effect on the local heat flux of spray cooling under the present test conditions.

Study on the Spray Behavior from Swirl and Fan Spray Type Gasoline Injectors Impinging on the Constant Temperature Flat Plate (스월형 및 팬스프레이형 고압직분식 가솔린 분사기의 상온 평판에서의 분무 충돌 특성에 관한 연구)

  • Kim, Chong-Min;Kang, Shin-Jae;Kim, Man-Young
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.2
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    • pp.100-106
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    • 2006
  • The behavior of spray impinging on the inclined constant temperature flat plate was experimentally investigated. To clarify the wall effect of a high pressure DISI injector, a relative angle of the inclined wall to a spray axis was varied. Spray penetration along the wall was observed optically and it was compared with that of a Fan spray type and Swirl type spray. To evaluate various spray motion quantitatively, a spray path penetration which describe the development of a spray tip along the wall was newly introduced. To observe the structure of an impinging spray, it was visualized by a controlled stroboscope light and its visualized image was captured on an CCD camera. Using the digital image of impinging spray $H_x$ and $R_x$ was extracted to clarify the structure of impinging spray. The main parameter of the relative position of the wall was the inclined angle which was defined as the angle was varied from $0^{\circ}$ (vertical impingement) to $60^{\circ}$ at the same condition.

A Study on the Spray Cooling Characteristics on the Angle of Hot Heat Transfer Surface (고온 열전달면의 각도에 따른 분무냉각특성에 관한 연구)

  • Yoon, D.H.;Kim, K.K.;Kim, M.H.;Oh, C.;Yoon, S.H.
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2001.11a
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    • pp.8-14
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    • 2001
  • The purpose of this study is to elucidate heat characteristics according to inclination angle of the hot flat plate at the spray cooling. As results of this experiment, the heat flux, the heat transfer coefficient and the cooling speed are increased as the liquid volume flux and subcooled temperature go up. And as the inclination angle of the heat transfer surface is increased, the cooling speed on the inclined flat plate becomes faster. It means that the cooling ability is increased because droplets were excluded by gravity.

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Numerical Study on the Fuel Spray Targeting for the Improvement of HSDI Engine Performance (HSDI 엔진 성능 향상을 위한 연료분사 타겟팅에 관한 수치 해석적 연구)

  • Min, Se Hun;Suh, Hyun Kyu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.9
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    • pp.569-576
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    • 2016
  • The objective of this study was to investigate, using a numerical method, the fuel injection targeting for improving the combustion performance in a HSDI diesel engine. In this work, the ECFM-3Z model was applied as the combustion model, and the injection mass, inclined spray angle, and injection timing were varied for the study on the targeting of fuel spray. The results of this work were compared in terms of cylinder pressure, rate of heat release, and exhaust emissions characteristics. It was found that the cylinder pressure increased when the injection timing was advanced, and the rate of heat release increased when more fuel was injected into the piston bowl. In addition, $NO_x$ emission increased owing to the increase in the rate of heat release. On the other hand, CO and soot emissions decreased because of the improvement in combustion performance.

Spreading Characteristics of a Liquid Droplet Impacting Upon the Inclined Micro-textured Surfaces (기울어진 미세 텍스쳐 표면에 충돌하는 단일 액적의 퍼짐 특성)

  • Shin, Dong-Hwan;Moon, Joo-Hyun;Lee, Seong-Hyuk
    • Journal of ILASS-Korea
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    • v.16 no.2
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    • pp.104-109
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    • 2011
  • The present study investigated experimentally the spreading characteristics of a single liquid impinging on the inclined micro-textured aluminum (Al 6061) surfaces manufactured by using a micro computerized numerical control (${\mu}$-CNC) milling machine. The textured surfaces were composed of patterned micro-holes (diameter of $125\;{\mu}m$ and depth of $125\;{\mu}m$). In our experiment, the de-ionized (DI) water droplet of $4.3\;{\mu}l$ was impinged normally on the non-textured and textured surfaces at two different Weber numbers, and the droplet impinged on the inclined surfaces with different angles. A high speed camera was used to capture sequential digital images for measurement of the maximum spreading distance. It was found that for the textured surface, the measured apparent equilibrium contact angle (ECA) increased up to $105.8^{\circ}$, higher than the measured ECA of $87.6^{\circ}$ for the non-textured (bare) surface. In addition, it is conjectured that the spreading distance decreased because of a liquid penetration during droplet spreading through the holes, the increase in hydrophobicity, and viscous dissipation during impact process.

Performance of Fire Extinguishing of Water Mist Nozzle for Power Transformer Fire Scenario (주 변압기실 화재시나리오에 적용한 미세물분무 노즐의 소화성능)

  • Lee, Kyoung-Duck
    • Journal of the Korean Society of Safety
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    • v.21 no.6 s.78
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    • pp.46-54
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    • 2006
  • Fire extinguishing experiment was conducted with water mist nozzle in case of the pool fire, cascade fire and spray fire on flammable liquid of class B whether water mist system can be effective system for power transformer fire scenario. In the event of a pool fire, flow rate and time to extinguish was inclined to be increased according to the obstruction rate of ignition space. Furthermore, the performance of fire extinguishing depended upon the spraying angle of the nozzles. In case of cascade fire, the effect of extinguishment was began to show from a combustion pan filled with fuel and fuel flowing plate later on.

A Study on the Flow Characteristics of Circular and Swirl Jets (원형 및 스월제트의 유동특성에 관한 연구)

  • Ko, Dong Guk;Yoon, Suck Ju
    • Journal of ILASS-Korea
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    • v.19 no.2
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    • pp.69-74
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    • 2014
  • The comparison of the flow characteristics between circular and swirl jets which were controlled by the spinner attachment inside the airtube were conducted in this study. Swirl jet means a flow in whirls by mixing the flow of axial and tangential direction. Swirl flow has been used for the improvement of the combustion efficiency in the combustor. This flow is controlled by the spinner which has several vanes inclined by certain angles to the axial direction. In this study, angle of vane $30^{\circ}$ and diameter ratio of outlet to inlet of the airtube 0.73 were made. These spec. should find on the general gun type burner built in the domestic small size boiler. As the flow characteristics, axial and tangential velocities were measured by using the 2-D hot-wire velocimeter system and analyzed statistically. And also this research conducted a practical experiment considering to the attached belongings likes as ignitor, nozzle etc. on the airtube of the gun type burner. As a result, swirl occurred at the occasion of beingness and flow region extended considerably toward the radial direction. But effect of swirl did not transmit to the downstream. And the complicated flow was appeared regardless of the existence of spinner because of the effect of belongings.