• 제목/요약/키워드: Inlet Flow Rate

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Experimental Study on Adjustment of Inlet Nozzle Section to Flow Rate Variation for Darrieus-type Hydro-Turbine

  • Watanabe, Satoshi;Shimokawa, Kai;Furukawa, Akinori;Okuma, Kusuo;Matsushita, Daisuke
    • International Journal of Fluid Machinery and Systems
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    • v.5 no.1
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    • pp.30-37
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    • 2012
  • A two dimensional Darrieus-type turbine has been proposed for the hydropower utilization of extra-low head less than 2m. In a practical use of Darrieus-type hydro-turbine, head and flow rate may be varied temporally and seasonally. Considering that the cost advantage is required for the low head hydro turbine system, the Darrieus turbine should be operated with high efficiency in the wider range of flow rate possibly by using an additional device with simpler mechanism. In the present paper, an adjustment of inlet nozzle section by lowering the inlet nozzle height is proposed to obtain the preferable inlet velocity in low flow rate conditions. Effects of resulting spanwise partial inlet flow are investigated. Finally, an effective modification of inlet nozzle height over flow rate variation is shown.

The Effect of Inlet Distorted Flow on Steady and Unsteady Performance of a Centrifugal Compressor (입구 비 균일 유동이 원심압축기의 정상 및 비정상 성능에 미치는 영향)

  • Kang Shin-Hyoung;Park Jae-Hyoung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.9 s.240
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    • pp.971-978
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    • 2005
  • Effects of inlet distorted flow on performance, stall and surge are experimentally investigated for a high-speed centrifugal compressor. Tested results for the distorted inlet flow cases are compared with the result of the undistorted one. The performance of compressor is slightly deteriorated due to the inlet distortion. The inlet distortion does not affect the number of stall cell and the propagation velocity. It also does not change stall inception flow rate. However, as the distortion increases, stall starts at the higher flow rate for low speed and at the lower flow rate for high speed. For 50,000 rpm stall occurrs as the flow rate decreases, however disappears fur the smaller flow rate. This is due to the interaction of surge and stall. After the stall and surge interact, the number of stall cell decreases.

Effects of the partial admission rate and cold flow inlet-outlet ratio on energy separation of Vortex Tube (Vortex Tube의 부분유입율과 저온 입.출구비가 에너지분리 특성에 미치는 영향)

  • 김정수;추홍록;상희선
    • Journal of the Korean Society of Safety
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    • v.13 no.3
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    • pp.51-59
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    • 1998
  • The vortex tube is a simple device for separating a compressed fluid stream into two flows of high and low temperature without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air conditioner for special purpose. The phenomena of energy separation through the vortex tube were investigated to see the effects of cold flow inlet-outlet ratios and partial admission rates on the energy separation experimentally. The experiment was carried out with various cold flow inlet-outlet ratios from 0.28 to 10.56 and partial admission rates from 0.176 to 0.956 by varying input pressure and cold air flow ratio. To find best use in a given cold flow inlet-outlet ratio and partial admission rate, the maximum temperature difference of cold air was presented. The experimental results were indicated that there are an optimum range of cold flow inlet-outlet ratio for each partial admission rate and available partial admission rate.

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CFD Simulation of the Effects of Inlet Flow rate on Hydraulic Behavior in Continuous Stirred-Tank Reactor (CSTR) (CFD 모사 기법을 이용한 유입 유량에 의한 연속 완전혼화 반응조 수리거동 고찰에 관한 연구)

  • Lee, Young Joo;Oh, Jeong Ik;Yoon, Sukmin;Kim, Jong-Oh;Park, No-Suk
    • Journal of Korean Society of Environmental Engineers
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    • v.38 no.1
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    • pp.25-33
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    • 2016
  • This paper describes three-dimensional computational fluid dynamics (CFD) simulation of liquid-liquid flow and transient tracer tests in a full-scale continuous stirred-tank reactor (CSTR) used for drinking water treatment. To evaluate the effects of inlet flow rate on hydrodynamic behavior in the selected CSTR, inlet flow rate was changed from 10% to 100% of the design flow rate. From the results of CFD simulation and analysis, as the inlet flow rate increases, Modal index and ${\beta}$ value are increased. Also, Morrill index shows local minimal points in relation to the inlet flow rate, which are observed at 20% and 40% of the design flow. As inlet flow Increases more than 40%, it is shown that Morrill index re-increases to close to ideal CSTR.

A Passive Flow-rate Regulator Using Pressure-dependent Autonomous Deflection of Parallel Membrane Valves (압력에 따른 평행박막 밸브의 자율 변형을 이용한 수동형 유량 제어기)

  • Doh, Il;Cho, Young-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.6
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    • pp.573-576
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    • 2009
  • We present a passive flow-rate regulator, capable to compensate inlet pressure variation and to maintain a constant flow-rate for precise liquid control. Deflection of the parallel membrane valves in the passive flowrate regulator adjusts fluidic resistance according to inlet fluid pressure without any external energy. Compared to previous passive flow-rate regulators, the present device achieves precision flow regulation functions at the lower threshold compensation pressure of 20kPa with the simpler structure. In the experimental study, the fabricated device achieves the constant flow-rate of $6.09{\pm}0.32{\mu}l/s$ over the inlet pressure range of $20{\sim}50$ kPa. The present flow-rate regulator having simple structure and lower compensation pressure level demonstrates potentials for use in integrated micropump systems.

Effect of inlet configuration on the growth rate of GaN layer in a MOCVD reactor (MOCVD 반응로내 GaN 성장에 미치는 입구형상의 영향)

  • Yun, Sung-Kyu;Baek, Byung-Joon;Pak, Bock-Choon
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.67-72
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    • 2003
  • Numerical calculation has been performed to investigate the effect of inlet configuration on the growth rate of GaN layer on the heated susceptor. The conventional single inlet, where the gas is mixed by force in the inlet, is compared with separated flow inlet. Two-parallel gas flow $H_{2}$ and $NH_{3}$ are separated by a plate with finite length which are also parallel to the susceptor. The effect of separated plate length, carrier gas and flow rate of each precursor on the mixing of reactant gases and growth rate were investigated. Furthermore the three dimensional model is employed to predict the transverse variation of growth rate.

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Heat and Flow Analysis Inside a Parallel-Flow Heat Exchanger (평행류 열교환기 내부의 열유동 해석)

  • Oh, Seok-Jin;Chung, Kil-Yoan;Lee, Kwan-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.6
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    • pp.781-788
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    • 2003
  • In the present study, the heat and flow characteristics of a parallel-flow heat exchanger are numerically analyzed by using three-dimensional turbulent modeling. Heat transfer rate and pressure drop are evaluated using the concept of the efficiency index by varying the locations, the shapes and angles of inlet/outlet, and the protrusion height of flat tube. It is found that negative angle of the inlet improves the heat transfer rate and pressure drop. Results show that the locations of the inlet and outlet should be toward the right side and the left side to the reference model, respectively, in order to enhance the heat transfer rate and pressure drop. Increasing the height of the lower header causes pressure drop to decrease and yields the good flow characteristics. The lower protrusion height of flat tube shows the improvement of the heat transfer rate and pressure drop. The heat transfer rate is greatly affected by the parameters of outlet side such as the location and angle of the outlet. However, the pressure drop is influenced by the parameters of inlet side such as the location and angle of inlet and the height of the header.

Design of Inlet Manifold for PEM Fuel Cells and Numerical Analysis (고분자 전해질 연료전지를 위한 연료주입구 설계 및 수치해석)

  • Uhm, Seung-Bae;Na, Tae-Kyung;Kim, Hong-Suk;Baek, Jung-Sik;Sung, Dong-Mug;Kim, Tae-Min
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.06a
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    • pp.172-175
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    • 2007
  • The Performance of a PEMFC stack is strongly dependent on the uniform reactants distribution on MEA. The uniform distribution can be achieved by flow-field pattern and manifold design optimized to satisfy operating conditions. This paper investigates uniform reactants distribution in channels by changing manifold shape and inlet mass flow rate. Typical U and Z shape and modified U and Z shape manifolds with buffer zone were designed. To check the uniform reactants distribution, standard deviation of mass flow rate was compared. The numerical results show that the inlet mass flow rate, inlet shape, and manifolds shape are critical factor for uniform distribution.

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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.

Effect of Flow Direction on Two-Phase Flow Distribution of Refrigerants at a T-Junction

  • Tae Sang-Jin;Cho Keum-Nam
    • Journal of Mechanical Science and Technology
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    • v.20 no.5
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    • pp.717-727
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    • 2006
  • The present study experimentally investigated the effect of flow direction and other flow parameters on two-phase flow distribution of refrigerants at a T-junction, and also suggested a prediction model for refrigerant in a T-junction by modifying previous model for air-water flow. R-22, R-134a, and R-410A were used as test refrigerants. As geometric parameters, the direction of the inlet or branch tube and the tube diameter ratio of branch to inlet tube were chosen. The measured data were compared with the values predicted by the models developed for air-water or steam-water mixture in the literature. We propose a modified model for application to the reduced T-junction and vertical tube orientation. Among the geometric parameters, the branch tube direction showed the biggest sensitivity to the mass flow rate ratio for the gas phase, while the inlet quality showed the biggest sensitivity to the mass flow rate ratio among the inlet flow parameters.