• Title/Summary/Keyword: Valve Opening Characteristics

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A Numerical Analysis for Fuel Consumption by Improvement of Intake/Exhaust Valve Timing in a Common Rail Diesel Engine for a Generator (커먼레일 디젤엔진의 흡배기밸브 타이밍 개선을 통한 연비절감에 대한 수치해석적 연구)

  • Kim, Seung Chul;Kim, Chung Kyun
    • Journal of Energy Engineering
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    • v.26 no.2
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    • pp.32-38
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    • 2017
  • The common rail diesel engine used in this study uses mechanically driven camshaft for the operation of intake and exhaust valves, and the timing of valve opening and closing is fixed according to the operating conditions of the vehicle. However, the electric generator engine operates at a constant speed and partial load. Therefore, in order to optimize the design of common rail diesel engine for power generation, the characteristics of diesel combustion and emissions according to the change of valve timing were examined and calculated in terms of fuel economy. The valve timing of the diesel engine influenced the combustion characteristics by changing the intake and exhaust flow and it was considered that the fuel efficiency of the generator could be improved.

A Numerical Study on the Flow Characteristics through an Industrial Safety Relief Valve (산업용 안전 릴리프밸브 유동특성에 관한 수치연구)

  • Kang, Sang-Mo;Lee, Bong-Hee
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.5
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    • pp.696-704
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    • 2009
  • In this paper, the flow characteristics through an industrial safety relief valve used to protect the crankcase room in a large-sized marine engine have been numerically investigated using the moving-mesh strategy. With the room pressure higher than the cracking one, the spring-loaded disc becomes open and then the air in the room blows off into the atmosphere, resulting in the reduction of the room pressure and then the shutoff of the disc. Numerical simulations are performed on the compressible air flow through the relief valve (${\phi}160mm$) with the initial room pressure (0.11 bar or 0.12bar) higher than the cracking one (0.1 bar). The numerical method has been validated by comparing the results with the empirical ones. Results show that the disc motion and flow characteristics can be successfully simulated using the moving-mesh strategy and depend strongly on the spring stiffness and the flow passage shape. With increasing spring stiffness, the maximum disc displacement decreases and thus the total disc-opening time also decreases. In addition, the flow passage shape makes a significant effect on the velocity and direction of the flow.

Analysis of Flow through High Pressure Bypass Valve in Power Plant (발전소용 고압 바이패스 밸브의 유동해석)

  • Cho, An-Tae;Kim, Kwang-Yong
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2558-2562
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    • 2007
  • In the present work, flow characteristics analysis has been performed for steam turbine bypass control valve (single-path type). The numerical analysis is performed by solving three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations. Shear stress transport (SST) model is used as turbulence closure. Symmetry condition is applied at the mid plane of the valve while adiabatic condition is used at the outer wall of the cage. Grid independency test is performed to find the optimal number of grid points. The pressure and temperature distributions on the outer wall of the cage are analyzed. Mass flow rate at maximum plug opening condition is compared with the designed mass flow rate.

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A Numerical Study on the Turbulent Flow Characteristics Near Compression TDC is Four-Valve-Per-Cylinder Engine (4밸브기관의 압축상사점 부근의 난류특성에 관한 수치해석적 연구)

  • 김철수;최영돈
    • Transactions of the Korean Society of Automotive Engineers
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    • v.1 no.1
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    • pp.1-13
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    • 1993
  • The three-dimensional numerical analysis for in-cylinder flow of four-valve engine without intake port has been successfully computed. These computations have been performed using technique of the general coordinate transformation based on the finite-volume method and body-fitted non-orthogenal grids using staggered control volume and covariant variable as dependent one. Computations are started at intake valve opening and are carried through top-dead-center of compression. A k-$\varepsilon$model is used to represent turbulent transport of momentum. The principal study is the evolution of interaction between mean flow and turbulence and of the role of swirl and tumble in generating near TDC turbulence. Results for three different inlet flow configuration are presented. From these results, complex flow pattern may be effective for promoting combustion in spark-ignition engines and kinetic energy of mean flow near TDC is well converted into turbulent kinetic energy.

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Characteristics of High Temperature Fatigue for welding material by Plasma Transferred Arc Weld (플라즈마 분말 용접재의 고온피로특성)

  • Choi, Seong-Dae;Cheong, Seon-Hwan;Kweon, Hyun-Kyu;Kim, Gi-Man;Kim, Jam-Kyu
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.6 no.3
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    • pp.92-97
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    • 2007
  • The overlay welding the automobile where the durability is demanded, it is used in the vessel engine valve, plant valve and pump parts. Cause of damage public opinion one what is thought is the fatigue load due to the opening and shutting operation right time repetition of the engine valve. The damage cause of the engine valve or explanation of destruction mechanism is very difficult. The research which it sees to make clear a overlay welding of Co-alloy by Plasma Transferred Arc Weld Surfacing Process reconsideration fatigue crack initiation and fatigue crack growth mechanism at high temperature.

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A study on the Characteristics of In-Cylinder Intake Flow in Spark Ignition Engine Using the PIV

  • Lee Suk-Young;Jeong Ku-Seob;Jeon Chung-Hwan;Chang Young-June
    • Journal of Mechanical Science and Technology
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    • v.19 no.2
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    • pp.704-715
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    • 2005
  • In this study, to investigate in-cylinder tumble or swirl intake flow of a gasoline engine, the flow characteristics were examined with opening control valve (OCV) and several swirl control valves (SCV) which intensify intake flow through steady flow experiment, and also turbulent characteristics of in-cylinder flow field were investigated by 2-frame cross-correlation particle image velocimetry (PIV) method. In the investigation of intake turbulent characteristics using PIV method, the different flow characteristics were showed according to OCV or SCV figures. The OCV or SCV installed engine had higher vorticity and turbulent kinetic energy than a baseline engine, especially around the wall and lower part of the cylinder. Above all, SCV B type was superior to the others. About energy dissipation and reynolds shear stress distribution, a baseline engine had larger loss than OCV or SCV installed one because flow impinged on the cylinder wall. It should be concluded, from what has been said above, as swirl component was added to existing tumble flow adequately, it was confirmed that turbulent intensity was enlarged, flow energy was conserved effectively through the experiment. In other words, there is a suggestion that flow characteristics as these affected to in-cylinder combustion positively.

Analysis of Dynamic Characteristics and Performances of Vent-Relief Valve (산화제 벤트/릴리프 밸브의 동특성 해석 및 작동성능 분석)

  • Jang, Je-Sun;Koh, Hyeon-Seok;Han, Sang-Yeop;Lee, Kyung-Won
    • Journal of the Korean Society of Propulsion Engineers
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    • v.15 no.6
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    • pp.70-77
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    • 2011
  • A ventilation-relief valve performs as a safety-valve assembly for the liquid-propellant feeding system of space launch vehicle. This valve plays a role of relieving the vaporized propellants from propellant tanks during the filling and storing stages of propellants. Also it regulates to maintain the pressure of ullage volume of on-board propellant tanks within the safety-margin during the flight. The simulation model of ventilation-relief valve is designed with AMESim to predict and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of the opening and closing pressures and their operating durations of valve by AMESim analysis are compared with the results of mathematical methods. In addition, the results of internal flow simulation with FLUENT are utilized to improve the accuracy of valve-modeling. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditionss, which shall be used in Korea Space Launch Vehicle-II.

Flow Characteristics inside a Throttle Valve Used to Control the Intake Air Flow in Engines (엔진의 흡기 공기량 조절용 스로틀 밸브에서의 유동 특성)

  • Kim, Sung-Cho;Kim, Cheol
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.8
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    • pp.91-98
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    • 1999
  • This paper describes the air flow characteristics inside the throttle valve. Tow-dimensional steady incompressible Navier-Strokes equation are solved numerically with embedding the conceopt of the artificial compressibility and adopting the Baldwin-Lomax turbulence model. With varying the valve opening angles(the Reynolds number )such as 15$^{\circ}$(5000) , 45$^{\circ}$(3000) , 75$^{\circ}$(7000) and 90$^{\circ}$(10000), respectively. tow cases, with a valve shaft and without one, are analysed. The pressure loss between the entrance and exit is severe at 15$^{\circ}$, 100 times as larger as that of 90$^{\circ}$ case, which also depends much on the existece of the valve shaft. The counter rotating vortices are formed over the valve plate with the shaft at only 75$^{\circ}$. They are smally and very large scale in front and back of the valve shaft , respectively. The velocity profiles of 15$^{\circ}$ and 90$^{\circ}$ at the exit are almost symmetric to the horizontal center line, however, the symmetricity is no longer maintained at 45$^{\circ}$ and 75$^{\circ}$ , and in addition, the flow at 75$^{\circ}$ is enforced a lot below center line. The pressure distribution on the walls is largely changed near the valve shaft, and its magnitude becomes great as the valve angle decreases.

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Numerical Simulation of The Pressure-Flow Control Characteristics of Shunt Valves Used to Treat Patients with Hydrocephalus (수두층 치료용 션트밸브의 압력-유량 제어특성 수치해석)

  • 장종윤;이종선;서창민
    • Journal of Biomedical Engineering Research
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    • v.22 no.5
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    • pp.403-412
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    • 2001
  • The Present study analyzed the pressure-flow characteristics of a Korean shunt valve. Changes in the characteristic currie depending on the design parameters were also investigated. The Korean shunt valve used in the present study was constant pressure type and our analyses were validated through experiments. We applied fluid-structure interaction to solve the flow dynamic Problem because the small diaphragm in the valve was made from flexible silicone elastomers. Considering the material nonlinearity of the hyper-elastic material. the Mooney-Rivlin approximation was employed. The results of the numerical analyses were close to the experimental results The major Pressure drop was observed to happen in the small diaphragm. The slope of the pressure-flow characteristic curve was computed to be 0.37mm$H_2O$.hr/cc, which was similar to the average value of commercial shunt valves. 0.40mm$H_2O$.hr/cc. Therefore. our valves analyzed in the Present study showed a Proper Pressure control characteristics of the constant pressure type shunt valves. The opening pressure could be controlled by adjusting the amount of predeflection of the valve diaphragm. In order to obtain opening pressures of 25mm$H_2O$ and 80mm$H_2O$, respectively, and the required predeflection was found to be 10.2$\mu$m and 35.3$\mu$m. The flow orifice size was found to be within 10$\mu$m during valve operation Therefore, Precision design and manufacturing techniques are necessary for successful operations of the shunt valve. The study indicated the amount of predeflection as well as the magnitude of corner rounding of the diaphragm edge are important design parameters to influence the slope of the pressure-flow characteristic curve.

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