• Title/Summary/Keyword: Secondary injection system

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ROSA/LSTF test and RELAP5 code analyses on PWR steam generator tube rupture accident with recovery actions

  • Takeda, Takeshi
    • Nuclear Engineering and Technology
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    • v.50 no.6
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    • pp.981-988
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    • 2018
  • An experiment was performed for the OECD/NEA ROSA-2 Project with the large-scale test facility (LSTF), which simulated a steam generator tube rupture (SGTR) accident due to a double-ended guillotine break of one of steam generator (SG) U-tubes with operator recovery actions in a pressurized water reactor. The relief valve of broken SG opened three times after the start of intact SG secondary-side depressurization as the recovery action. Multi-dimensional phenomena specific to the SGTR accident appeared such as significant thermal stratification in a cold leg in broken loop especially during the operation of high-pressure injection (HPI) system. The RELAP5/MOD3.3 code overpredicted the broken SG secondary-side pressure after the start of the intact SG secondary-side depressurization, and failed to calculate the cold leg fluid temperature in broken loop. The combination of the number of the ruptured SG tubes and the HPI system operation difference was found to significantly affect the primary and SG secondary-side pressures through sensitivity analyses with the RELAP5 code.

The Effects of Secondary Fuel Injection on Combustion Oscillation

  • Shigeru Tachibana;Laurent Zimmer;Park, Gyung-Min;Takeshi Yamamoto;Ufosawa, Yoji-K;Seiji Yoshida;Kazuo Suzuki
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.376-379
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    • 2004
  • The purpose of this work is to develop an effective active control system for combustion instabilities of premixed combustors. For the first step, the natural modes of combustion oscillation were investigated for a methane-air premixed combustor and the controls by secondary fuel injection were examined. The main premixed flame is stabilized by a swirler with orifices for secondary injection installed on the central hub. For sensing purposes, a pressure transducer and a chemiluminescence sensor were placed on the appropriate positions. The acoustic characteristics and the source of the oscillation were analyzed by those signals. To test the controllability, two methods of actuations by secondary fuel injection were examined. One is the open loop control and the other is the closed loop control. The comparison of the reduction levels of p $_{rms}$ shows that the closed loop control with a phase-shift injection performs best in this condition.ition.n.

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Computational Study on the Fluidic Thrust Vectoring of a Propellant Jet (추진제트의 Fluidic Thrust Vectoring에 관한 수치해석 연구)

  • 김재형;임채민;김희동;조재필
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2003.05a
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    • pp.23-26
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    • 2003
  • Recently, the thrust vector control using a secondary flow injection which is accomplished by injecting a secondary flow into the supersonic exhaust flow through hole in the wall of the propulsion nozzle has been attention in the applications of the rocket propulsion system. In the present study, 3-dimensional compressible, Navier-Stokes equation to understand the SITVC(Secondary Injection Thrust Vector Control) flow field. The computational results are validated with previous experimental data available. The computational results are visualized detailed structure of shock wave induced by secondary flow and deflected supersonic jets.

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Performance Analysis of Secondary Gas Injection for a Conical Rocket Nozzle TVC(II) (2차 가스분사에 의한 원추형 로켓노즐 추력벡터제어 성능해석 (II))

  • Song, Bong-Ha;Ko, Hyun;Yoon, Woong-Sup;Lee, Sang-Kil
    • Journal of the Korean Society of Propulsion Engineers
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    • v.5 no.1
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    • pp.18-25
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    • 2001
  • The results of systematic numerical experiments of secondary gas injection thrust vector control are presented. The effects of secondary injection system such as injection location and nozzle divergent cone angle onto the overall performance parameters such as thrust ratio, specific impulse ratio and axial thrust augmentation, are investigated. Complex nozzle exhaust flows induced by the secondary jet penetration is numerically analyzed by solving unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with Baldwin-Lomax turbulence model for closure. Numerical simulations compared with the experiments of secondary air injection into the rocket nozzle of $9.6^{\cire}$ divergent half angle showed good agreement. The results obtained in terms of overall performance parameters showed that locating the secondary injection orifice further downstream of primary nozzle ensures the prevention of occurrence of reflected shock wave, therefore is suitable for efficient and stable thrust vectoring over a wide range of use.

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Study of the Thrust Vector Control using a Secondary Flow Injection (2차 유동 분사에 의한 제트 유동의 추력 제어에 관한 연구)

  • Jung Sung-Jae;Szwaba Ryszard;Kim Heuy-Dong;Ahn Jae-Mun;Jung Dong-Ho
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.119-122
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    • 2002
  • In general, Liquid Injection Thrust Vector Control(LITVC) is accomplished by injecting a liquid into the supersonic exhaust flow through holes in the wall of the propulsion nozzle. This injection flow field is highly complicated and detailed flow physics associated with the secondary flow injection should be known far the practical design and use of the LITVC system. The present study aims at understanding the LTTVC flow field and obtaining fundamental design parameters for LITVC. The experimentations were performed in a supersonic blow-down wind tunnel. Compressed, dry air was used for both the main exhaust and injection flows but the pressures of these two flows were controlled independently. The location of the injection holes was changed and the pressures of the two streams were also changed between 2.0 and 15.0 bar. The effectiveness of LITVC was discussed in details using the results of the pressure measurements and flow visualizations

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CFD Analysis on the Fresh Air Distribution in the Catalytic Converter Varying Secondary Air Injector Position (2차 공기 분사 위치에 따른 촉매 내 공급 공기 분포에 대한 전산 유동해석)

  • Yun, Jeong-Eui
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.5
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    • pp.31-36
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    • 2010
  • SAI(Secondary Air Injection) system has been studied widely as one of the promising countermeasure for reducing HC emission at cold start. In this paper, in order to find out the optimal position of SAI, computational thermal fluid analysis on exhaust system adapted SAI system is performed using commercial 3-D CFD code, CFX. The present results showed that SAI position strongly affected the uniformity of air distribution in front of catalyst. And also through the decision process of optimal position of SAI, new index, uniformity of air distribution($U_{\phi}$) is proposed to define it quantitively. Because $U_{\phi}$ is very simple equation and similar with flow uniformity, it is very easy to figure out the physical meaning and to apply it to practices. Finally, we applied the index $U_{\phi}$ to the decision process of the optimal position of SAI, so that we could get the clear comparison results.

An Analytical Study on Characteristics of a Diesel Injection System (디젤분사계의 특성에 관한 해석적 연구)

  • 장영준;박호준;전충환
    • Journal of Advanced Marine Engineering and Technology
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    • v.13 no.4
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    • pp.63-74
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    • 1989
  • It is well-known that the fuel injection system if a diesel engine has taken a more important place in understanding of diesel combustion process with combustion chamber. But a diesel fuel injection system has an assembly of many complex and intricate problems such as the desired rate of injection, secondary injection and injection pump etc., in addition to the atomization for ignition and combustion, the penetration and diestribution for proper utilization of air. The analysis is carried out by simplifing and modeling the injection phenomena and dividing into three parts comprising of fuel injection pump, high pressure pipe and fuel injection nozzle. The purpose of this paper is to describe an analytical simulation of the injection system and to speed up the work of developing injection systems for new engines. The effects of important injection parameters as predicted by the present model are found to be in good agreement with experiment. It can be seen that there is an optimal pipe diameter for maximum quantity injected.

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Influence of changing combustor pressure on flame stabilization and NOx emission in swirl flame (연소실 압력변동이 스월 화염에서 화염 안정화와 NOx 배출에 미치는 영향)

  • Kim, Jong-Ryul;Choi, Gyung-Min;Kim, Duck-Jool
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.569-572
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    • 2006
  • In present study, the influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOX) emission in the swirl flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P^*=Pabs/Patm$), where Pabs and Patm indicated the absolute pressure and atmosphere pressure, was controlled in the range of 0.7~1.15 for each equivalence ratio conditions. It could be observed that flame stable region became narrower with decreasing equivalence ratio and pressure index. In this combustion system, stable flames were formed until $P^*=\;0.7$. Emission index decreased with decreasing pressure index for overall equivalence ratio conditions and NOx reduction rates were almost identical for $P^*<1$ regardless of equivalence ratio though EINOx values showed different level with change of equivalence ratio for $P^*{\geq}1$. It is also observed that EINOx decreased with increasing secondary fuel injection ratio. Emission index of nitric oxide was controllable by adjusting the changing combustor pressure and injecting secondary fuel and this NOx reduction technology is applicable to industrial furnaces and air conditioning system.

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Effect of Secondary Air on Flow and Combustion Characteristics in a Pyrolysis Melting Incinerator (열분해 용융소각로 연소실의 2차공기 주입 영향에 관한 전산해석 및 실험)

  • Jeon, Byoung-Il;Park, Sang-Uk;Shin, Dong-Hoon;Ryu, Tae-Woo;Jeon, Kum-Ha;Hwang, Jung-Ho;Lee, Jin-Ho
    • 한국연소학회:학술대회논문집
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    • 2004.06a
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    • pp.149-157
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    • 2004
  • In the present paper we studied experimentally fundamental optimization of oxygen enriched pyrolysis melting incinerator, Characteristics of this system was confirmed dealing with the gas flow and combustion properties for the inside secondary air injection. The experiment setup has a disposal rate of 30kg/hr which was measured by the inside temperature and gas. Along with above experiments, the three-dimensional computation was employed to analyse the combustion fluid dynamics and gas residence time. Equations for turbulence and heat - transmission as well as chemical reactions were solved by using common codes. The experimental combustion chamber was composed of staged combustion types structure for reducing NOx. Finally, it was verified that the control of the secondary air and air ratio of thermo stack were important. In the computational analysis, it showed reasonable agreement with the experimental results regarding the temperature and discharged gas concentration.

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Flow Characteristics of Oil Jet for Cooling a Piston (피스톤 냉각용 엔진오일 제트 유동특성)

  • Li, L.;Lee, J.H.;Jung, H.Y.;Kim, J.H.;Lee, Y.W.
    • Journal of Power System Engineering
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    • v.10 no.4
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    • pp.50-55
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    • 2006
  • An efficient cooling system for a piston of an automotive engine is very important. Therefore a large capacity gasoline engine or diesel engine has adopted the direct injection cooling system to increase its cooling efficiency. In this direct cooling system, an cooling oil is injected to a piston directly using an oil jet and this cooling oil flows through an oil gallery inside the piston. Flow rate and injection accuracy of this cooling oil are very important because these are main factors that have influence on its efficiency. The purpose of this study is to understand the changes of flow characteristics with various curvatures and diameters of an outlet nozzle and to check whether engine oil enters into the oil gallery well or not. From this study, we found that secondary flow was formed in a curved part of jet due to centrifugal force and irregular flow pattern appeared at the jet outlet. This pattern has influence on flow characteristics of engine oil entering the gallery. These simulation results have a good agreement with experiments.

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