• Title/Summary/Keyword: dynamic flow

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Flow Control for High Pressure Gas by using a Solenoid Valve (솔레노이드 밸브를 이용한 고압가스의 유량제어)

  • Sim Han-sub;Lee Chi-woo;Kim Nam-kyung;Ahn Kook-chan;Namkoong Chai-kwan
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2005.05a
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    • pp.156-161
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    • 2005
  • Dynamic flow characteristics of a solenoid valve are affected by pressure difference in inlet and outlet of orifice, gas temperature, and supply voltage of a coil. In this paper, the dynamic flow characteristics for deviations of various conditions are studied Static and dynamic flow for variation on-time of a solenoid valve open signal are measured in basic bench test. The solenoid valve is applied to a compressed natural gas(CNG) engine test for validation of flow control performance. The experimental results show that flow of high pressure gas can controlled precisely by using a solenoid valve.

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Modeling and Simulation for PIG Flow Control in Natural Gas Pipeline

  • Nguyen, Tan-Tien;Kim, Sang-Bong;Yoo, Hui-Ryong;Park, Yong-Woo
    • Journal of Mechanical Science and Technology
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    • v.15 no.8
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    • pp.1165-1173
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    • 2001
  • This paper deals with dynamic analysis of Pipeline Inspection Gauge (PIG) flow control in natural gas pipelines. The dynamic behaviour of PIG depends on the pressure differential generated by injected gas flow behind the tail of the PIG and expelled gas flow in front of its nose. To analyze dynamic behaviour characteristics (e.g. gas flow, the PIG position and velocity) mathematical models are derived. Tow types of nonlinear hyperbolic partial differential equations are developed for unsteady flow analysis of the PIG driving and expelled gas. Also, a non-homogeneous differential equation for dynamic analysis of the PIG is given. The nonlinear equations are solved by method of characteristics (MOC) with a regular rectangular grid under appropriate initial and boundary conditions. Runge-Kutta method is used for solving the steady flow equations to get the initial flow values and for solving the dynamic equation of the PIG. The upstream and downstream regions are divided into a number of elements of equal length. The sampling time and distance are chosen under Courant-Friedrich-Lewy (CFL) restriction. Simulation is performed with a pipeline segment in the Korea gas corporation (KOGAS) low pressure system. Ueijungboo-Sangye line. The simulation results show that the derived mathematical models and the proposed computational scheme are effective for estimating the position and velocity of the PIG with a given operational condition of pipeline.

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Modelling and Simulation for PIG Flow Control in Natural Gas Pipeline

  • Nguyen, Tan-Tien;Yoo, Hui-Ryong;Park, Yong-Woo;Kim, Sang-Bong
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.448-448
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    • 2000
  • This paper deals with dynamic behaviour analysis for pipeline inspection gauge (PIG) flow control in natural gas pipeline. The dynamic behaviour of the PIG is depending on the different Pressure between the rear and nose parts, which is generated by injected gas flow behind PIG's tail and expelled gas flow in front of its nose. To analyze the dynamic behaviour characteristics such as gas flow in pipeline, and the PIG's position and velocity, mathematical model is derived as two types of a nonlinear hyperbolic partial differential equation for unsteady flow analysis of the PIG driving and expelled gas, and nonhomogeneous differential equation for dynamic analysis of PIG. The nonlinear equation is solved by method of characteristics (MOC) with the regular rectangular grid under appropriate initial and boundary conditions. The Runge-Kuta method is used when we solve the steady flow equations to get initial flow values and the dynamic equation of PIG. The gas upstream and downstream of PIG are divided into a number of elements of equal length. The sampling time and distance are chosen under Courant-Friedrich-Lewy (CFL) restriction. The simulation is performed with a pipeline segment in the Korea Gas Corporation (KOGAS) low pressure system, Ueijungboo-Sangye line. The simulation results show us that the derived mathematical model and the proposed computational scheme are effective for estimating the position and velocity of PIG with different operational conditions of pipeline.

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Measurement of Dynamic Characteristics of an Inducer in Cavitating Conditions

  • Ashida, Takuya;Yamamoto, Keita;Yonezawa, Koichi;Horiguchi, Hironori;Kawata, Yutaka;Tsujimoto, Yoshinobu
    • International Journal of Fluid Machinery and Systems
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    • v.10 no.3
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    • pp.307-317
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    • 2017
  • In liquid-propellant rockets, POGO instability can occur, in which a fluctuation of propellant supply to the engine, a thrust fluctuation, and a structural vibration are coupled. For the prediction of this instability, it is required to provide dynamic characteristics of the pump represented as the transfer matrix correlating the upstream and downstream pressure and flow rate fluctuations. In the present study, the flow rate fluctuation is evaluated from the fluctuation of pressure difference at the different locations assuming that the fluctuation is caused by the inertia of the flow rate fluctuation. The experiments were performed in some flow conditions, and it was shown that the tendencies of dynamic characteristics are related to excitation frequencies, cavitation numbers and flow rate coefficients.

A Physically Based Dynamic Recrystallization Model for Predicting High Temperature Flow Stress (열간 유동응력 예측을 위한 물리식 기반 동적 재결정 모델)

  • Lee, H.W.;Kang, S.H.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.22 no.8
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    • pp.450-455
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    • 2013
  • In the current study, a new dynamic recrystallization model for predicting high temperature flow stress is developed based on a physical model and the mean field theory. In the model, the grain aggregate is assumed as a representative volume element to describe dynamic recrystallization. The flow stress and microstructure during dynamic recrystallization were calculated using three sub-models for work hardening, for nucleation and for growth. In the case of work hardening, a single parameter dislocation density model was used to calculate change of dislocation density and stress in the grains. For modeling nucleation, the nucleation criterion developed was based on the grain boundary bulge mechanism and a constant nucleation rate was assumed. Conventional rate theory was used for describing growth. The flow stress behavior of pure copper was investigated using the model and compared with experimental findings. Simulated results by cellular automata were used for validating the model.

Dynamic Stability and Response Analysis of Piping System with Internal Flow (내부에 유체가 흐르는 파이프계의 동적안정성 및 응답해석)

  • 이우식;박철희;홍성철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.1861-1871
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    • 1991
  • In this study, the piping system conveying unsteady flow is considered. The effects of coupling between the pipe motion and the velocity and pressure of fluid are included for the dynamic stability and response analysis of the piping system. The dynamic equations for a piping system are derived by Newtonian dynamics. For the momentum and continuity equations, the concept of moving control volume is applied. Thus, the governing equations derived herein are valid for the applications to the vibration problems occurred when a piping system starts up or shuts down and also when the valves and pumps operate. For a simply supported straight pipe, the stability analysis is conducted for various nondimensional parameters. The dynamic responses, in both stable and unstable region of stability chart, are numerically tested by the use of central difference method.

A Study on Flow Rate Characteristic and Dynamic Performance on Diaphragm Solenoid Valve (다이어프램형 밸브의 유량특성과 동적성능에 관한 연구)

  • Jeong, C.S.;Yang, S.Y.
    • Journal of Drive and Control
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    • v.10 no.3
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    • pp.27-33
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    • 2013
  • Solenoid valve has used in various industrial field extensively. A solenoid valve has different size, shape and method of operation accordantly to industrial field. Many researchers study on kinds of solenoid valve such as flow rate, dynamic, magnetic field, valve shape and operating method. But the flow rate characteristic and dynamic response time performance on the diaphragm valve are not studied. This paper describes the flow rate characteristic and dynamic response time performance on the diaphragm valve. At first, the diaphragm valve is simulated in AMESim simulation tool. AMESim model found that an effect of valve performance depends on parameter. The parameter is the diaphragm orifice area. And the performance test bench confirms the effect in this parameter. Finally, it finds out the flow rate characteristic and dynamic response time performance on the diaphragm valve.

Dynamic evolution characteristics of water inrush during tunneling through fault fracture zone

  • Jian-hua Wang;Xing Wan;Cong Mou;Jian-wen Ding
    • Geomechanics and Engineering
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    • v.37 no.2
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    • pp.179-187
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    • 2024
  • In this paper, a unified time-dependent constitutive model of Darcy flow and non-Darcy flow is proposed. The influencing factors of flow velocity are discussed, which demonstrates that permeability coefficient is the most significant factor. Based on this, the dynamic evolution characteristics of water inrush during tunneling through fault fracture zone is analyzed under the constant permeability coefficient condition (CPCC). It indicates that the curves of flow velocity and hydrostatic pressure can be divided into typical three stages: approximate high-velocity zone inside the fault fracture zone, velocity-rising zone near the tunnel excavation face and attenuation-low velocity zone in the tunnel. Furthermore, given the variation of permeability coefficient of the fault fracture zone with depth and time, the dynamic evolution of water flow in the fault fracture zone under the variable permeability coefficient condition (VPCC) is also studied. The results show that the time-related factor (α) affects the dynamic evolution distribution of flow velocity with time, the depth-related factor (A) is the key factor to the dynamic evolution of hydrostatic pressure.

Dynamic PIV analysis of High-Speed Flow Ejected from the Inflator Housing of a Curtain-type Airbag (Dynamic PIV를 이용한 커튼형 에어백 부품림 장치의 유동해석)

  • Jang, Young-Gil;Kim, Seok;Lee, Sang-Joon
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.407-408
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    • 2006
  • Passenger safety is one of the most important considerations in the purchase of an automobile. A curtain-type air bag is increasingly adapted in deluxe cars for protecting passengers from the danger of side clash. Inflator housing is a main part of the curtain-type air bag system for supplying high-pressure gases to pump up the air bag-curtain. Although the inflator housing is fundamental in designing a curtain-type air bag system, flow information on the inflator housing is very limited. In this study, we measured instantaneous velocity fields of a high-speed flow ejecting from the inflator housing using a dynamic PIV system. From the velocity field data measured at a high frame-rate, we evaluated the variation of the mass flow rate with time. From the instantaneous velocity fields of flow ejecting from the airbag inflator housing in the initial stage, we can see a flow pattern of broken shock wave front and its downward propagation. The flow ejecting from the inflator housing was found to have large velocity fluctuations and the maximum velocity was about 700m/s. The velocity of high-speed flow was decreased rapidly and the duration of high-speed flow over 400m/s was maintained only to 30ms. After 100ms, there was no perceptible flow.

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Effect of Friction Force on the Dynamic Characteristics of a Flow Divider Valve (Flow Divider Valve의 동특성에 미치는 마찰력의 영향)

  • 박태조;황태영
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.1
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    • pp.198-203
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    • 2000
  • In this paper, a numerical analysis is carried out to show the effect of friction farce on the dynamic characteristics of a flow divider valve. The continuity equations and the equation of motion fur spool are numerically solved. The viscous friction force acting on the spool is considered analyzing the Reynolds equation which governs the viscous flow in the clearance gap between the spool and sleeve. Dynamic characteristics are highly affected by the viscous friction farce whose magnitude is relatively small compare with other fluid forces. Therefore present theoretical formulation and numerical scheme can be used generally in designing and performance evaluation of all the hydraulic spool valve.

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