• Title/Summary/Keyword: External Mixing

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Model Parametrization on the Mixing Behavior of Coastal Discharges

  • Kim, Jong-Kyu
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.6 no.1
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    • pp.15-21
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    • 2003
  • A common feature in the three-dimensional numerical model experiments of coastal discharge with simplified model and idealized external forcings is investigated. The velocity fields due to the buoyancy and flaw flux, are spreaded radiately and the surface velocites are much greater than the homegeneous discharges. The coastal dischargd due to the Coriolis force and flaw flux are shaped a anticyclical gyre (clockwise) and determined the scale of the gyre in the coastal zone, respectively. The bottom topography restricts a outward extention of the coastal fronts and it accelerates a southward flow.

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Development of Sub-scale Combustor for a Liquid Rocket Engine Using Swirl Injector with External Mixing (외부혼합 와류분사기를 장착한 액체로켓엔진용 축소형 연소기 개발)

  • Han, Yeoung-Min;Kim, Seung-Han;Seo, Seong-Hyeon;Lee, Kwang-Jin;Kim, Jong-Gyu;Seol, Woo-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.10
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    • pp.102-111
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    • 2004
  • The procedure of design and manufacture of sub-scale combustor using bipropellant swirl injector with external mixing for a liquid rocket engine are described. The results of cold flow test, ignition test and combustion test of the sub-scale combustor are also given in this paper. The sub-scale combustor uses liquid oxygen(LOx) and kerosene as propellants and has a injector head, an ablative material combustor wall and a water cooled nozzle. The injector head has LOx manifold, fuel manifold, fire face plate, one center swirl injector and 18 main swirl injectors. The cold flow, ignition and combustion tests were successfully performed without damage of combustor. Results of hot firing tests show that combustion efficiency meets the target of design and operations of start and stop cyclogram are stable and high frequency combustion instability does not occur.

Characteristics of Droplet Properties in the Two-Phase Spray into a Subsonic Cross Flow

  • Lee, I.C.;Cho, W.J.;Koo, J.Y.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.358-363
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    • 2008
  • The spray cross-section characteristics of two-phase spray that using external-mixing nozzle injected into a subsonic cross flow were experimentally studied with various ALR ratio that is $0{\sim}59.4%$. Suction type wind tunnel was used and experiments were conducted to ambient environment. Several plain orifice nozzles with L/d of 30 and orifice diameter of 0.5 mm and orifice length 1.5 mm were tested. Free stream velocity profiles at the injection location were measured using hot wire. Spray images were captured to study collision point and column trajectory. Phase Doppler particle analyzer(PDPA) was utilized to quantitatively measuring droplet SMD, volume flux. Measuring probe of PDPA positions was moved 3-way transverse machine. SMD distributions were layered structure and peaked at the top of the spray plume and low value at bottom of the spray. Volume flux of spray was distributed to the two side region and volume flux quantity decreased when ALR ratio increased. It was found that the perpendicularly injected two-phase spray jet of external mixing into a cross flow showing that mistlike spray moved away from the test section bottom region.

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Dynamic Characteristics of External loop Air-Lift Reactor (외부 순환 공기리프트 반응기의 동특성)

  • 강귀현;김춘영정봉우
    • KSBB Journal
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    • v.7 no.1
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    • pp.59-65
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    • 1992
  • Hydrodynamics and mixing characteristics such as circulation time, mixing time, circulation velocity and axial dispersion coefficient were investigated using highly viscous pseudoplastic solutions of carboxymethyl cellulose(CMC) in an external circulation loop air-lift reactor with 13$\ell$ working volume. The superficial gas velocity was changed from 1.9 to 6.2cm/s and CMC concentration from 0 to 1.0wt%. The theoretical model based on the pressure balance is developed mathematically to predict liquid circulation velocity. Gas hold-up, circulation velocity and axial dispersion coefficient of liquid phase increased with increasing gas velocity and decreased slightly with increasing liquid viscosity. Mixing time and circulation time decreased with increasing gas velocity and increased with increasing liquid viscosity. Experimental data on liquid circulation velocity were in good agreement with the predicted values.

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Triboelectrostatic Separation System for Separation of PVC and PS Materials Using Fluidized Bed Tribocharger

  • Lee, Jae-Keun;Shin, Jin-Hyouk;Hwang, Yoo-Jin
    • Journal of Mechanical Science and Technology
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    • v.16 no.10
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    • pp.1336-1345
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    • 2002
  • A triboelectrostatic separation system using a fluidized bed tribocharger for the removal of PVC material in the mixture of PVC/PS plastics is designed and evaluated as a function of electric field strength, air flow rate, and the mixing ratio of two-component mixed plastics. It consists of a fluidized-bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PS particles can be imparted negative and positive surface charges, respectively, due to the difference in the work function values of plastics suspended in the fluidized-bed tribocharger, and can be separated by passing them through an external electric field. Experimental results show that separation efficiency is strongly dependent on the electric Deld strength and particle mixing ratio. In the optimum conditions of 150 Ipm air flow rate and 2.6 kV/cm electric field strength a highly concentrated PVC (99.1%) can be recovered with a yield of more than 99.2% from the mixture of PVC and PS materials for a single stage of processing.

Combustion Performance Characteristics of a High Pressure Sub-scale Liquid Rocket Combustor (고압 축소형 연소기의 연소 성능 특성에 관한 연구)

  • Kim, Jong-Gyu;Lee, Kwang-Jin;Seo, Seong-Hyeon;Han, Yeoung-Min;Choi, Hwan-Seok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.5
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    • pp.31-36
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    • 2007
  • Combustion performance characteristics of subscale high-pressure combustor were investigated at 70 bar combustion pressure. All tests were successfully performed without any damage on the combustor. The mixing characteristics and distribution pattern of the injectors were found to have considerable influence on the combustion performance. The characteristic velocity of the combustor was higher in the injector with internal mixing than that of external mixing and in the injector with smaller mass flowrate. The pressure fluctuations at the propellant manifolds and the combustion chamber were measured to be less than 3% of the mean combustion pressure to meet the combustion stability criterion and to prove stable combustion characteristics of the combustor.

Model Parametrization on the Mixing Behavior of Coastal Discharges

  • Kim, Jong-Kyu
    • Journal of Ocean Engineering and Technology
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    • v.17 no.2
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    • pp.1-7
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    • 2003
  • A common feature in the three-dimensional numerical model experiments of coastal discharge with simplifed model and idealized external forcings is investigated. The velocity fields due to the buoyancy and flow flux, are spreaded radiately and the surface velocites are much greater than homegeneous discharges. The coastal dischargd due to the Coriolis force and flow flux are shaped a anticyclical gyre (clockwise) and determined the scale of the gyre in the coastal zone, respectively. The bottom topography restricts a outward extention of the coastal fronts and it accelerates a southward flow.

Spray characteristics and nozzle design experiment to twin-fluid atomizer (이유체 분무기의 분무특성 및 노즐설계 실험)

  • Jeong, Jin-Do;Ji, Pyeong-Sam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.6
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    • pp.1941-1947
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    • 1996
  • Droplet size measurement technique was established for the sprayed viscous fluid by virtue of the installation of the sprayed-droplet size measurement system employing light scattering method. Atomization test results showed that the mean droplet size of the sprayed viscous fluid is decreased with the increase of the mass ratio of air to fuel and in case of the same air/fuel ratio, also with the increase of viscous fluid flow rate, and is increased with the distance from atomizer tip. Basic design data for the manufacture of external-mixing type, Y-Jet type, and internal-mixing type atomizers was acquired from the atomization tests.

Robust Design for Shape Parameters of High Pressure Thermal Vapor Compressor by Numerical Analysis (전산해석을 통한 고압열증기압축기 형상변수에 관한 강건 설계)

  • Park, Il-Seouk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.12
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    • pp.931-937
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    • 2008
  • A high motive pressure thermal vapor compressor(TVC) for a commercial multi-effect desalination(MED) plant is designed to have a high entraining performance and its robustness is also considered in the respect of operating stability at the abrupt change of the operating pressures like the motive and suction steam pressure which can be easily fluctuated by the external disturbance. The TVC having a good entraining performance of more than entrainment ratio 6.0 is designed through the iterative CFD analysis for the various primary nozzle diameter, mixing tube diameter and mixing tube length. And then for a couple of TVC having a similar entrainment ratio, the changes of the entrainment ratio are checked along the motive and suction pressure change. The system stability is diagnosed through the analyzing the changing pattern of the entrainment ratio.

Transient Behaviour of Photorefractive $Bi_{12}SiO_{20}$ Crystal: Two Wave Mixing with an External A.C. Field (A.C. 전장이 인가된 광굴절 Bi12SiO20 결정의 2광파 혼합 이득의 시간종속 변화)

  • 곽종훈
    • Korean Journal of Optics and Photonics
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    • v.4 no.1
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    • pp.73-83
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    • 1993
  • The temporal differential equation describing the build-up of the space-charge field in the presence of square and sinusoidal alternating field in photorefractive materials is solved analytically. We also measured the average two-wave mixing gain and the full temopral gain variations in a B$i_{12}$Si$O_{20}$ crystal with applied fields of up to 7 KV/cm amplitude and 1 KHz repetition rate. It has been found that the experimental measurements agree well with the theoretical results.

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