Processing math: 100%
  • Title/Summary/Keyword: CFX

Search Result 512, Processing Time 0.029 seconds

Oblique Angle Effect of Impinging Jet on Heat Flow Characteristics of a Corrugated Structure (충돌제트의 경사각도가 파형 구조의 열유동 특성에 미치는 영향)

  • Hwang, Byeong Jo;Kim, Seon Ho;Joo, Won Gu;Cho, Hyung Hee
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.21 no.2
    • /
    • pp.83-93
    • /
    • 2017
  • A numerical analysis is made of the fluid flow and heat transfer characteristics in the corrugated structure that traps the spent air in the corrugations between impinging jets to reduce crossflow effects on downstream jets in the array. All computations are performed by considering three-dimensional, steady state, and incompressible flow by using the ANSYS-CFX 15.0 code. Averaged jet Reynolds number is 10,000. The oblique angles of impingement jets on the spanwise section are 70, 80, 90, and the oblique angles of impingement jets on the streamwise section are 70, 90, 110. The investigation focuses on the oblique angle influence of impinging jet array on the fluid flow and heat transfer characteristics of a corrugated structure.

CFD validation for subcooled boiling under low pressure (저압에서의 과냉각 비등 현상에 대한 CFD의 유효성 검토)

  • Choi, Yong-Seok;Kim, You-Taek;Lim, Tae-Woo
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.40 no.4
    • /
    • pp.275-281
    • /
    • 2016
  • Subcooled boiling under low pressure was numerically investigated using computational fluid dynamics(CFD). The wall boiling model was used for simulating the subcooled boiling; this model requires sub-models consisting of bubble departure diameter, nucleation site density and bubble departure frequency. The CFD code CFX provides the default models based on experimental data. Because these models are mostly developed under high pressure conditions, it would not be predicted well in low pressure conditions. Thus in this study, CFD validation for subcooled boiling under low pressure was analyzed. The numerical results were compared with experimental data from published paper. Simulations were performed with mass flux ranging from 250 to 750kg/m2s, heat flux ranging from 0.37 to 0.77MW/m2 and constant outlet pressure of 0.11 MPa. Employing the empirical correlation developed under low pressures could increase the accuracy of numerical analysis.

Numerical Analysis of Flow Distribution Inside a Fuel Assembly with Split-Type Mixing Vanes (분할 형태 혼합날개가 장착된 연료집합체 내부유동 분포 수치해석)

  • Lee, Gong Hee;Cheong, Ae Ju
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.40 no.5
    • /
    • pp.329-337
    • /
    • 2016
  • As a turbulence-enhancing device, a mixing vane, which is installed at a spacer grid of the fuel assembly, plays an important role in improving convective heat transfer by generating either swirl flow in the subchannels or cross flow between the fuel rod gaps. Therefore, both the geometric configuration and the arrangement pattern of a mixing vane are important factors in determining the performance of a mixing vane. In this study, in order to examine the flow-distribution features inside a 5×5 fuel assembly with split-type mixing vanes, which was used in the benchmark calculation of the OECD/NEA, we conduct simulations using the commercial computational fluid dynamics software, ANSYS CFX R.14. We compare the predicted results with measured data obtained from the MATiS-H (Measurement and Analysis of Turbulent Mixing in Subchannels-Horizontal) test facility. In addition, we discuss the effect of the split-type mixing vanes on the flow pattern inside the fuel assembly.

Investigating the Power-Performance Prediction on an H- and Helical-type Tidal Current Turbine Using CFD Method (CFD에 의한 H 및 Helical 타입 조류발전용 터빈의 출력성능예측에 관한 연구)

  • Kim, Bum Suk
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.39 no.8
    • /
    • pp.653-660
    • /
    • 2015
  • In this study, we conduct power performance and load analyses of two different types of vertical-axis tidal-current turbines using the computational fluid dynamics (CFD) method. To analyze the power output and loads, we perform transient CFD simulations considering the cavitation model using ANSYS CFX. The averaged power output of an H-type rotor was 7.47 kW and 67.6 kW in normal and extreme operating conditions, respectively, which did not satisfy the initial design conditions. However, in the case of the helical-type rotor, the power output under normal and extreme conditions were close to the expected values. The cavitation, which may cause instantaneous power fluctuation, occurred repeatedly at the suction side of the rotors. In order to guarantee a more stable power supply and to prevent fatigue failure, we require a design that minimizes cavitation.

Study on Indoor Flow According to Vane Angle of Square Ceiling Type Louver Diffuser (사각 천장형 루버 디퓨저의 토출 각도에 따른 실내유동에 관한 연구)

  • Jang, Heon-Deock;Lee, Dae-Hui;Lee, Jin-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.36 no.7
    • /
    • pp.683-687
    • /
    • 2012
  • The purpose of this paper is to numerically study the characteristics of the indoor air flow of a square ceiling type diffuser according to the vane angle and flow rate. The CFX of ANSYS 13.0 was used for the CFD tool. The size of the room is 6m(X)×6m(Y)×2.7m(Z). The exhaust diffuser was positioned diagonally to the supply diffuser. This diffuser was designed to have many holes, so the air supply had long throw patterns with low velocity decay. The characteristics of the indoor air flow was studied at volume flow rates of 5.1 CMM and 7.4 CMM, and a vane angle from 30 to 60, every 10.

Numerical Study of Fluidic Device in APR1400 Using Free-Surface Model (자유수면모델을 활용한 APR1400 유량조절장치의 수치해석 연구)

  • Lim, Sang-Gyu;You, Sung-Chang;Kim, Han-Gon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.36 no.7
    • /
    • pp.767-774
    • /
    • 2012
  • A fluidic device (FD) has been adopted in the safety injection tanks (SITs) of APR1400. A flow control mechanism of the FD was used to vary the flow regime in the vortex chamber corresponding to the SITs water level. The flow regime in the vortex chamber has a different pressure loss from low to high in accordance with the SITs water level. Nitrogen at the top of the SIT could be released owing to inertia of discharge flow when changing from a high flow rate to a low flow rate. This phenomenon is important to design improvement perspective because it can affect the performance of the FD. This paper shows a result of a preliminary numerical study to obtain the transient data related to air release in the flow turn-down period using a two-fluid free-surface model provided from ANSYS CFX 13.0. In conclusion, there is no significant effect on the performance of the FD, though a small quantity of air is released during the flow turn-down period.

Deriving Reference Data for Alarm System in a Container Crane by Fluid-Structure Interaction Analysis (유동구조연성해석을 통한 컨테이너 크레인의 경보시스템용 기준 데이터 도출)

  • Han, Dong-Seop;Han, Geun-Jo;Kwak, Ki-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.34 no.8
    • /
    • pp.1091-1096
    • /
    • 2010
  • This study was conducted to provide reference data for designing an alarm system that can help prevent the overturning of a container crane under wind load. Two methods, namely, fluid-structure interaction (FSI) analysis and windtunnel test, were adopted in this investigation. To evaluate the effect of wind load on the stability of the crane, a 50-ton-class container crane that is widely used in container terminals was adopted as the analysis model and 19 values were considered as design parameters for wind direction. First, the wind-tunnel test for the reduced-scale container crane model was performed according to the wind direction by using an Eiffel type atmospheric boundary-layer wind tunnel. Next, the FSI analysis for the real-scale container crane was conducted using ANSYS and CFX. Then, the uplift force determined from the FSI analysis was compared with that determined from the wind-tunnel test. Finally, a formula to compensate for the difference between the results of the FSI analysis and the wind-tunnel test was proposed.

Evaluation of Aerodynamic Characteristics of NREL Phase VI Rotor System Using 2-Way Fluid-Structure Coupled Analysis Based on Equivalent Stiffness Model (등가강성모델 기반의 양방향 유체구조 연성해석을 적용한 NREL Phase VI 풍력 로터 시스템의 공력특성 평가)

  • Cha, Jin-Hyun;Song, Woo-Jin;Kang, Beom-Soo;Kim, Jeong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.36 no.7
    • /
    • pp.731-738
    • /
    • 2012
  • In this study, the evaluation of the aerodynamic characteristics of the NREL Phase VI Rotor System has been performed, for the 7 m/s upwind case using commercial FEA and CFD tools which are ANSYS Mechanical 12.1 and CFX 12.1. The initial operating conditions of the rotor blade include a 3 tip pitch angle. A numerical simulation was carried out on only the rotor parts, excluding the tower structure based on the equivalent stiffness model, to consider the aeroelastic effect for the numerical simulation using the loosely coupled 2-way fluid-structure interaction method. The blade root bending moment was monitored in real time to obtain reasonable results. To verify the analysis results, the numerical simulation results were compared with the measurements in the form of the root bending moment and the pressure distributions of the NREL/NASA Ames wind tunnel test.

Development of Load-Cell-Based Anemovane (로드셀형 풍향풍속계 개발)

  • Jeon, Byeong Ha;Han, Dong Seop;Lee, Kwon-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.37 no.5
    • /
    • pp.685-691
    • /
    • 2013
  • A load-cell-type anemovane operates based on wind vector properties. The developed load-cell-type anemovane is of a fixed type in which the wing does not rotate, unlike in the case of existing anemovanes. The load-cell-type anemovane is required to accurately derive the correlation between the load ratio and the wind direction in order to develop a qualified product. This is because the load ratio repeats every 90 owing to the use of four load cells, and its value varies nonlinearly according to the wind direction. In this study, we compared analytical results with experimental results. Fluid analysis was carried out using ANSYS CFX. Furthermore, the prototype was tested using a self-manufactured wind tunnel. The wind direction was selected as the design variable. 13 selected wind direction conditions ranging from 0 to 90 with an interval of 7.5 for analysis were defined. Furthermore, 10 wind direction conditions with an interval of 10 for the experiment were defined. We derived the relations between the pressure ratio and the wind direction through the experiment and fluid analysis.

Application of Numerical Model for the Effective Design of Large Scale Fire Calorimeter (화재발열량계의 효율적 설계를 위한 수치해석 모델의 적용)

  • Kim, Sung-Chan
    • Fire Science and Engineering
    • /
    • v.24 no.6
    • /
    • pp.28-33
    • /
    • 2010
  • The present study develops a numerical model based on the computational fluid dynamics technique to analyse the thermal flow characteristics of large scale fire calorimeter and examine the characteristics of primary parameters affecting on the uncertainty of heat release rate measurement. ANSYS CFX version 12.1 which is a commercial CFD package is used to solve the governing equations of the thermal flow field and the eddy dissipation combustion model and P-1 radiation model are applied to simulate the fire driven flow. The numerical results shows that the horizontal duct system with 90 bend duct was shown relatively high deviated asymmetric flow profiles at the sampling location and the deviation of the velocity field was higher than that of the temperature and species quantities. The present study shows that the computational model can be applicable to optimize the design process and operating condition of the large scale fire calorimeter based on the understanding of the detail flow field.