• 제목/요약/키워드: Mixing characteristics

검색결과 2,871건 처리시간 0.032초

Recess Effects on Spray Characteristics of Swirl Coaxial Injectors

  • Seol, J.H.;Han, P.G.;Jeong, W.H.;Yoon, Y.
    • International Journal of Aeronautical and Space Sciences
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    • 제4권1호
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    • pp.26-33
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    • 2003
  • Recess is a geometrical configuration shape that the exit surface of an inner injector is located at a certain length inward from that of an outer injector. It is known to have the characteristics that it can augment mixing efficiency and flame stabilization through internal mixing of propellant in it. So, various experiments, such as backlit stroboscopic photography, phase Doppler particle analyzer(PDPA) and mechanical patternator, were performed at several recess lengths to grasp its effect on the spray characteristics of spray angle, breakup length, atomization and' mixing. Recess length was normalized to dimensionless recess number and two principal mechanisms of impingement and swirl recovery were introduced to explain its influence on the spray characteristics. The effect of recess on SMD doesn't appear significantly near the recess number where mixing efficiency attains to the maximum, whereas mass distribution and mixing efficiency are changed considerably. Thus, it can be inferred that a certain optimum recess number exists, where mixing efficiency becomes the maximum.

특수교반날개를 사용한 DCM 공법의 지반 관입 특성에 대한 사례연구 (Case Studies of Penetration Characteristics of DCM Wall Using Spiral Mixing Blades in Soil Layers)

  • 정두회;정경환;양태선
    • 한국지반공학회논문집
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    • 제23권3호
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    • pp.133-140
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    • 2007
  • DCM공법(심층혼합처리 공법)은 흙막이 벽체 등 구조물 조성에 적용하였다. 이러한 DCM 벽체는 경질층에서 관입능력이 있어야 한다. DCM 장비에 부착된 교반날개에 의해 경질지반의 관입능력이 증가되는 알아보기 위해 특수교반날개가 고안되었다. 경질점토층에 관입되는 특수교반날개의 관입특성은 김해와 인천현장에서 조사하였다. 고안한 특수교반날개는 관입속도가 다소 느려도 N=30 이상 되는 지반까지 관입되었고 관입시 효율이 경질지반에서 낮아질 수 있으므로 경제적인 교반날개의 관입깊이를 분석하였다.

타이어 정련 공정 스케줄링을 위한 유전자 알고리즘 (Genetic Algorithms for Tire Mixing Process Scheduling)

  • 안의국;박상철
    • 한국CDE학회논문집
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    • 제18권2호
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    • pp.129-137
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    • 2013
  • This paper proposed the scheduling method for tire mixing processes using the genetic algorithm. The characteristics of tire mixing process have the manufacturing routing, operation machine and operation time by compound types. Therefore, the production scheduling has to consider characteristics of the tire mixing process. For the reflection of the characteristics, we reviewed tire mixing processes. Also, this paper introduces the genetic algorithm using the crossover and elitist preserving selection strategy. Fitness is measured by the makespan. The proposed genetic algorithm has been implemented and tested with two examples. Experimental results showed that the proposed algorithm is superior to conventional heuristic algorithm.

임펠러 형상에 따른 교반기의 유동특성에 관한 연구 (A Study on the Flow Characteristics of Mixer by Impeller Types)

  • 양창조;최민선;이영호
    • Journal of Advanced Marine Engineering and Technology
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    • 제27권7호
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    • pp.899-905
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    • 2003
  • Mixers are used in several industrial applications where it is necessary to strongly mix reactants in a short period of time (eg. reaction injection molding, ceramics manufacturing, crystallization). However, despite their widespread use, mixing flow characteristics in these systems have not been rigorously investigated. Influence of blade shapes on the mixing time and the power consumption per unit volume in two kinds of impeller including the mixing effects are studied by PIV experiment. A series of the experiments were carried out to achieve a better mixing effect in simple baffle arrangement and tall vessel with modified impellers(two kinds of blades : pitched blade turbine and rushton turbine). Results show that periodic vortex from the mixing layer is predominant and related unsteady flow characteristics prevail over the entire region.

초음속 유동장 내 연료 다중 분사의 혼합 특성 (Mixing Characteristics of Multiple Injection in Supersonic Flow)

  • 이종환;이상현
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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    • pp.53-56
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    • 2004
  • The mixing characteristics of a multiple transverse injection system in a scramjet combustor were studied with numerical methods. The distance among injectors on mixing characteristics were investigated. The three-dimensional Wavier-Stokes equations including k-w SST turbulence model were solved. It was shown that the mixing characteristics of a multiple transverse injection system were very different from those of a single and a dual injection system; the rear injection flow was strongly influenced by blocking effect due to the momentum flux of the front injection flow and thus had higher expansion and penetration than the front injection flow. The multiple injection system had higher mixing rate, higher penetration but had more losses of stagnation pressure than the single injection system.

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Effect of Swirling Flow by Normal Injection of Secondary Air on the Gas Residence Time and Mixing Characteristics in a Lab-Scale Cold Model Combustor

  • Shin, D.;Park, S.;Jeon, B.;Yu, T.;Hwang, J.
    • Journal of Mechanical Science and Technology
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    • 제20권12호
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    • pp.2284-2291
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    • 2006
  • The present study investigates gas residence time and mixing characteristics for various swirl numbers generated by injection of secondary air into a lab-scale cylindrical combustor. Fine dust particles and butane gas were injected into the test chamber to study the gas residence time and mixing characteristics, respectively. The mixing characteristics were evaluated by standard deviation value of trace gas concentration at different measurement points. The measurement points were located 25 mm above the secondary air injection position. The trace gas concentration was detected by a gas analyzer. The gas residence time was estimated by measuring the temporal pressure difference across a filter media where the particles were captured. The swirl number of 20 for secondary air injection angle of 5$^{\circ}$ gave the best condition: long gas residence time and good mixing performance. Numerical calculations were also carried out to study the physical meanings of the experimental results, which showed good agreement with numerical results.

SMART 유동혼합헤더집합체 열혼합 특성 해석 (CFD ANALYSIS FOR THERMAL MIXING CHARACTERISTICS OF A FLOW MIXING HEADER ASSEMBLY OF SMART)

  • 김영인;배영민;정영종;김긍구
    • 한국전산유체공학회지
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    • 제20권1호
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    • pp.84-91
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    • 2015
  • SMART adopts, very unique facility, an FMHA to enhance the thermal and flow mixing capability in abnormal conditions of some steam generators or reactor coolant pumps. The FMHA is important for enhancing thermal mixing of the core inlet flow during a transient and even during accidents, and thus it is essential that the thermal mixing characteristics of flow of the FMHA be understood. Investigations for the mixing characteristics of the FMHA had been performed by using experimental and CFD methods in KAERI. In this study, the temperature distribution at the core inlet region is investigated for several abnormal conditions of steam generators using the commercial code, FLUENT 12. Simulations are carried out with two kinds of FMHA shapes, different mesh resolutions, turbulence models, and steam generator conditions. The CFD results show that the temperature deviation at the core inlet reduces greatly for all turbulence models and steam generator conditions tested here, and the effect of mesh refinement on the temperature distribution at the core inlet is negligible. Even though the uniformity of FMHA outlet hole flow increases the thermal mixing, the temperature deviation at the core inlet is within an acceptable range. We numerically confirmed that the FMHA applied in SMART has an excellent mixing capability and all simulation cases tested here satisfies the design requirement for FMHA thermal mixing capability.

미소진동교반기의 혼합특성에 대한 수치적 연구 (Numerical Study for Mixing Characteristics of an Oscillating Micro-stirrer)

  • 김용대;맹주성
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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    • pp.309-312
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    • 2006
  • Effective mixing is an important problem in microfluidics for chemical and biomechanical applications. In this study, the influences of the Reynolds number and the oscillating frequency on mixing characteristics of micro-stirrer are studied in a microchannel with single stirrer. The influence of fluid inertial effects in an active mixer is first discussed. It is found that the stirring effects by stirrer oscillation are promptly attenuated at low Reynolds number, which makes greatly difficult the rapid mixing. As the inertial effects are increased, the chaotic advection is generated and then developed. The mixing phase is finally developed some mushroom shaped structure. And the mixing efficiency is also studied as a function of the oscillating frequency. We found that the mixing efficiency does not always increase with higher oscillating frequency of stirrer. Consequently, we found the functional relation between the optimal frequency of a stirrer and the Reynolds number.

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기연가스의 혼합이 상호작용을 하는 예혼합화염의 소화특성에 미치는 영향에 관한 연구 (Effect of burnt gas mixing on the extinction of interacting flames premixed)

  • 임홍근;정석호
    • 오토저널
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    • 제11권3호
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    • pp.37-48
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    • 1989
  • The effects of burnt gas mixing, which can be caused by turbulent eddy mixing, on the interaction and extinction characteristics of premixed flames are analyzed using large activation energy asymptotics adopting counterflow as a model problem. The results show that the burnt gas mixing, preferential diffusion and heat loss affect the fuel consumption rate, flame temperature and the oxidizer concentration at the flame which influence the flame behavior and the extinction characteristics.

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정적혼합기술 응용 열교환기의 압력손실 및 열전달 특성 (Pressure Loss and Heat Transfer Characteristics of Heat Exchanger Using Static Mixing Technology)

  • 박상규;양희천;전준철
    • Journal of Advanced Marine Engineering and Technology
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    • 제30권1호
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    • pp.65-72
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    • 2006
  • Heat transfer augmentation in heat exchangers has received much attention in recent years, mainly due to energy efficiency and environmental considerations. Many active and Passive techniques are currently being employed in heat exchangers, with some inserts providing a cost-effective and efficient means of augmenting heat transfer. The Purpose of this paper is to determine the pressure loss and heat transfer characteristics of a heat exchanger using static mixing technology. Experimental measurements were taken on two set-ups: a single tube heat exchanger and a shell-tube heat exchanger with two static mixing inserts. It was concluded that the static mixing inserts resulted in an increase in the pressure loss and heat transfer characteristics as can be expected.