• Title/Summary/Keyword: Inlet Guide Vane

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Diagnostics of nuclear reactor coolant pump in transition process on performance and vortex dynamics under station blackout accident

  • Ye, Daoxing;Lai, Xide;Luo, Yimin;Liu, Anlin
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2183-2195
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    • 2020
  • A mathematical model for the flowrate and rotation speed of RCP during idling was established. The numerical calculation method and dimensionless method were used to analyze the flow, head, torque and pressure and speed changes under idle conditions. Regularity, using the Q criterion vortex identification judgment method combined with surface flow spectrum morphology analysis to diagnose the vortex dynamic characteristics on RCP blade. On impeller blade, there is two oscillations in the pressure ratio on pressure surface in blade outlet region. The velocity on the suction surface is two times more oscillating than the inlet of blade, and there is an intersection with the velocity ratio curve on pressure surface. On blade of guide vane, the pressure ratio increases along the inlet to outlet direction, and the speed ratio decreases with the increase of idle time. There is a vortex that rotates counterclockwise on the suction surface, and the streamline on the suction surface of blade is subjected to the entrainment and blocking action of the vortex creates a large reverse flow in the main flow region. There are two vortices at the outlet of guide vane suction side and the vortices are in opposite directions.

Numerical Analysis of Flow Uniformity in Selective Catalytic Reduction (SCR) Process Using Computational Fluid Dynamics (CFD)

  • Shon, Byung-Hyun
    • International Journal of Advanced Culture Technology
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    • v.10 no.3
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    • pp.295-306
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    • 2022
  • The NOx removal performance of the SCR process depends on various factors such as catalytic factors (catalyst composition, shape, space velocity, etc.), temperature and flow rate distribution of the exhaust gas. Among them, the uniformity of the flow flowing into the catalyst bed plays the most important role. In this study, the flow characteristics in the SCR reactor in the design stage were simulated using a three-dimensional numerical analysis technique to confirm the uniformity of the airflow. Due to the limitation of the installation space, the shape of the inlet duct was compared with the two types of inlet duct shape because there were many curved sections of the inlet duct and the duct size margin was not large. The effect of inlet duct shape, guide vane or mixer installation, and venturi shape change on SCR reactor internal flow, airflow uniformity, and space utilization rate of ammonia concentration were studied. It was found that the uniformity of the airflow reaching the catalyst layer was greatly improved when an inlet duct with a shape that could suppress drift was applied and guide vanes were installed in the curved part of the inlet duct to properly distribute the process gas. In addition, the space utilization rate was greatly improved when the duct at the rear of the nozzle was applied as a venturi type rather than a mixer for uniform distribution of ammonia gas.

Computational Fluid Dynamic Analysis for Improving the Efficiency of Desulfurization System for the Wet Flue Gas (습식 배연탈황 시스템의 효율 향상을 위한 전산해석)

  • Hwang, Woo-Hyeon;Lee, Kyung-Ok
    • Journal of the Korea Society of Computer and Information
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    • v.19 no.2
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    • pp.161-171
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    • 2014
  • In this paper the flow dynamics of the flue gas equipment in the desulfurization system was numerically analyzed by simulating the problems for the turbulent and combustion flow from Induced Draft Fan(I.D.Fan) outlet to Booster Up Fan(B.U.Fan) inlet using the commercial CFD software of CFD-ACE+ in CFDRC company for Computational Fluid Dynamic Analysis. The guide vane of this section was examined for the minimum pressure loss and the uniform flow dynamic to B.U.Fan with the proper velocity from I.D,Fan exit to B,U,Fan inlet section at the boiler both the maximum continuous rating and the design base. The guide vanes at I,D.Fan outlet and B.U.Fan inlet were removed and modified by numerical simulation of the CFD analysis. The flue gas at the system had the less pressure loss and the uniform flow dynamics of the flow velocity and flow line by comparing with the old design equipment.

Study of the Supersonic Ejector-Diffuser System with a Mixing Guide Vane (혼합 안내깃을 적용한 초음속 이젝터-디퓨져 시스템에 대한 연구)

  • Kong, Fanshi;Jin, Yingzi;Kim, Heuydong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.17 no.1
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    • pp.52-60
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    • 2013
  • Ejector-diffuser system makes use of high-pressure primary stream to entrain the low-pressure secondary stream through pure shear action between two streams. In general, the flow field in the ejector-diffuser system is highly complicated due to turbulent mixing, compressibility effects. A fatal drawback of the ejector system is in its low efficiency. Many works have been done to improve the performance of the ejector system, but not yet satisfactory. In the present study, a mixing guide vane was installed at the inlet of the secondary stream for the purpose of the performance improvement of the ejector system. A CFD method has been applied to simulate the supersonic flows inside the ejector-diffuser system. The present results obtained were validated with existing experimental data. The mixing guide vane effects are discussed in terms of the entrainment ratio, total pressure loss as well as pressure recovery.

Performance Analysis of Francis Turbines by CFD (CFD을 이용한 프란시스 수차의 내부유동 해석)

  • Choi, Hyen-Jun;Hwang, Young-Cheol;Kim, You-Taek;Nam, Chung-Do;Lee, Young-Ho
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.191.2-191.2
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    • 2010
  • The conventional method to assess turbine performance is its model testing which becomes costly and time consuming for several design alternatives in design optimization. Computational fluid dynamics (CFD) has become a cost effective tool for predicting detailed flow information in turbine space to enable the selection of best design. In the present paper, Francis turbine of commercial small hydropower plants which is under 70kw is investigated. Solutions are investigated with respect to the hydraulic characteristics against an outward angle of guide vane, the number of guide vane and head (inlet velocity). By suitable modification of the runner shape, low pressure zone on the leading edge can be reduced. If the entire runner is to be optimized in this manner, flow simulation tests have to be carried out on a series of different geometrical shape.

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Effect of Circumferential Velocity from Guide Vane on the Nozzle Flow of a Jet Fan (제트팬 노즐내부 유동에 대한 고정익 출구 원주속도의 영향)

  • 최충현;이재헌
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.3
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    • pp.209-216
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    • 2001
  • A numerical study is peformed to investigate the effect of circumferential velocity generated by the guide vane on the nozzle flow of a jet fan, s a way of increasing the penetration force of jet fan with nozzle of 175mm diameter. For the validation of numerical results. the velocity is measured by a 5-hole pitot tube and flow visualization is conducted by the tuft method. Under the inlet condition that the maximum circumferential velocity in the stator outlet of the present jet fan is 1.8m/s, the axial velocity in the nozzle outlet has the feature that the velocity at the axis is low and the velocity near the wall high. Therefore, to increase the throw length of the jet fan, the configuration of the fairing and nozzle needs to be developed and the precise revise of the stator angle is required, In addition, the bigger the circumferential velocity, the smaller the axial velocity at the axis and the bigger non-uniformity of the flow distribution.

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A Study on the Flow Characteristic of Non-Thermal Plasma Reactor for Demonstration (실증실험용 저온 플라즈마 반응기의 유동특성에 관한 연구)

  • Kim, Y.S.;Choi, S.H.;Kim, J.I.;Kim, T.H.;Yoo, J.S.;Paek, M.S.;Jang, G.H.
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.508-513
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    • 2000
  • HANJUNG has developed demonstration plant treating combustion flue gas such as dioxide($SO_2$) and nitrogen oxides(NOx). Before operating this system, we tested the inner airflow characteristic of demonstration plant in the front of plasma reactor field 1 and field 2. The experimental results of $25,000Nm^3/hr$ airflow are compared with the computational results using FLUENT code. It is found that the velocity distribution trends are matched the experimental results with the calculation results. To improve the eccentric airflow in the inlet hood, it is necessary to install the vertical guide vane as well as the horizontal guide vane.

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Measurement of Flow and Scalar Distribution at Gas Turbine Inlet Section (가스터빈 입구에서의 유동 및 스칼라 분포 특성)

  • Hong, Sung-Kook;Ireland, Peter;Denman, Paul
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.4
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    • pp.45-50
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    • 2010
  • The goal of paper is to investigate the flow and scalar distribution through the HP Nozzle Guide Vane (NGV) passage. Flow and scalar distribution measurement are conducted by using 5-hole pressure probe and $CO_2$ tracing technique, respectively. Three different experimental cases are considered depending on cooling flow condition. The result shows that the vortical secondary flow patterns are observed clearly and these flow characteristics maintain through the NGV passage regardless of cooling flow injection. Compared to center region, the high axial velocity flow is observed near wall region due to cooling flow injection. Without cooling flow, the $CO_2$ (scalar) distribution becomes to be uniform quickly due to the strong flow mixing phenomenon. However, in cases of cooling flow, scalar distribution is significantly non-uniform.

Parametric Study of 2.5 kW Class Propeller Type Micro Hydraulic Turbine (2.5 kW 급 프로펠러형 마이크로 수차 매개변수 연구)

  • MA, SANG-BUM;KIM, SUNG;CHOI, YOUNG-SEOK;CHA, DONG-AN;KIM, JIN-HYUK
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.4
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    • pp.387-394
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    • 2020
  • A parametric study of a 2.5 kW class propeller type micro hydraulic turbine was performed. In order to analyze the internal flow characteristics in the hydraulic turbine, three dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used and the hexahedral grid system was used to construct computational domain. To secure the reliability of the numerical analysis, the grid dependency test was performed using the grid convergence index method based on the Richardson extrapolation, and the grid dependency was removed when about 1.7 million nodes were used. For the parametric study, the axial distance at shroud span (L) between the inlet guide vane and the runner, and the inlet and outlet blade angles (β1, β2) of the runner were selected as the geometric parameters. The inlet and outlet angles of the runner were defined in the 3 spans from the hub to tip, and a total of 7 geometric parameters were investigated. It was confirmed that the outlet angles of the runner had the most sensitive effect on the power and efficiency of the micro hydraulic turbine.

Experimental Study of Compressor Surge for 250-hp Class Vehicular Turbocharger (250마력 급 차량용 터보차저 서지현상에 대한 실험적 연구)

  • Lee, Hyungchang;Han, Jaeyoung;Lee, Myeonghee;Im, Seokyoen;Yu, Sangseok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.1
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    • pp.89-95
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    • 2015
  • A surge phenomenon cause noise and pulsations in a turbo compressor, which is an unstable operating regime. Because surge protection ensures a safe compressor operation, it is important to understand the physics of the surge phenomenon. In this study, the surge characteristics of a 250-hp class turbo-compressor were evaluated experimentally. The experimental parameters were the rotational speed, opening angles of the inlet guide vane and exit valve, and inlet pipe diameter and flow rates of the inlet gases. The results showed that the compressor surge was very sensitive to the gas flow rates, exit pressure, rotational speed, and bypass flow rates.