• 제목/요약/키워드: Sliding mesh

검색결과 79건 처리시간 0.022초

렌지후드의 성능개선을 위한 시로코 팬 주위의 유동해석 (PERFORMANCE IMPROVEMENT OF A RANGE HOOD SIROCCO FAN BY CFD FLOW ANALYSIS)

  • 한병윤;박진우;이명수;박형구
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2008년도 학술대회
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    • pp.159-165
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    • 2008
  • A sirocco fan is widely used for discharging pollutants of a kitchen space since it is able to generate a relatively high air flow rate considering its small size and makes less noise than a axial fan or a centrifugal fan. However, it has a problem because its efficiency is low, and power consumption is larger. Performance of a sirocco fan is influenced by various factors such as number of the fan blades, diameter of the fan, geometry of the fan, geometry of its housing, revolution frequency, static pressure condition, and etc. This research investigated the effect on the performance of geometry of the housing. For CFD analysis, we used a commercial code, SC/Tetra, and used a sliding mesh method to give the same condition as an actual state. Verification of the CFD results is done by comparison of experimental data and numerical one about the suction flow rate, and it is confirmed that two results are well consistent. After we changed the shape of housing according to Archimedes' screw, we observed that suction efficiency is improved by 10.7% maximum.

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회전로터 및 후류 동하중을 고려한 스마트 무인기 천이응답해석 (Transient Response Analysis for a Smart UAV Considering Dynamic Loads by Rotating Rotor and Wakes)

  • 김현정;오세원;김성준;최익현;김태욱;이상욱;김진원;이정진;김동현
    • 한국소음진동공학회논문집
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    • 제16권9호
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    • pp.926-936
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    • 2006
  • In this study, structural vibration analyses of a smart unmanned aerial vehicle (UAV) have been conducted considering dynamic loads generated by rotating rotor and wakes. The present UAV (TR-S5-03) finite element model is constructed as a full three-dimensional configuration with different fuel conditions and tilting angles for helicopter, transition and airplane flight modes. Practical computational procedure for modal transient response analysis (MTRA) is established using general purpose finite element method (FEM) and computational fluid dynamics (CFD) technique. The dynamic loads generated by rotating blades in the transient and forward flight conditions are calculated by unsteady CFD technique with sliding mesh concept. As the results of present study, transient structural displacements and accelerations are presented in detail. In addition, vibration characteristics of structural parts and installed equipments are investigated for different fuel conditions and tilting angles.

중형 터보프롭 항공기급 프로펠러 공력특성 전산해석 (CFD Analysis of Aerodynamic Characteristics of Regional Turboprop Aircraft Propeller)

  • 최원;최재승;정인면;김지홍;이일우;한성훈;원영수
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2011년 춘계학술대회논문집
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    • pp.447-452
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    • 2011
  • Propeller shall have high efficiency and improved aerodynamic characteristics to get the thru5t to fly at high speed for the Regional turboprop aircraft. That is way Clark-Y airfoil which is used to conventional turboprop aircraft propeller is selected as a blade airfoil. Adkins method is used for aerodynamic design and performance analysis with respect to the propeller design point. Adkins method is based on the vortex-blade element theory which design the propeller to satisfy the condition for minimum energy loss. propeller geometry is generated by varying chord length and pitch angle at design point of Regional turboprop aircraft. The propeller design results indicate that is evaluated to be properly constructed, through analysis of propeller aerodynamic characteristics using the Meshless method and MRF, SM method.

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원자력 발전소용 순환수 펌프의 성능해석 (THE PERFORMANCE ANALYSIS OF A CIRCULATING WATER PUMP FOR A NUCLEAR POWER PLANT)

  • 이명수;한병윤;황도연;유성수;박형구
    • 한국전산유체공학회지
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    • 제14권3호
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    • pp.69-75
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    • 2009
  • The objective of this study is to investigate the suitable design for a domestic Circulating water pump(CWP), which is used in cooling-water intakes for the unit 3 and 4 of Yeonggwang nuclear power plant. All the simulations are performed, using CFD method with a commercial code STAR-CCM+ version 3.02. After modeling a present design of the pump, the flow around the rotating blade was calculated by using quasi-static method and sliding mesh method with the almost same condition as an actual state. Based on fundamental simulations with various depth of sea water, the reference pressure for the boundary condition of the present study was decided. To verify the reliability of the calculation results, the suction flow rate of the data was compared with that of the experimental data. As a result of this comparison, it is confirmed that two results are fairly consistent. For the improvement of the suction flow rate, computational analysis was done by changing a flow channel and blade shapes. It is shown that the suction flow rate of the new pump was improved.

Validation of the numerical simulations of flow around a scaled-down turbine using experimental data from wind tunnel

  • Siddiqui, M. Salman;Rasheed, Adil;Kvamsdal, Trond
    • Wind and Structures
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    • 제29권6호
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    • pp.405-416
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    • 2019
  • Aerodynamic characteristic of a small scale wind turbine under the influence of an incoming uniform wind field is studied using k-ω Shear Stress Transport turbulence model. Firstly, the lift and drag characteristics of the blade section consisting of S826 airfoil is studied using 2D simulations at a Reynolds number of 1×105. After that, the full turbine including the rotational effects of the blade is simulated using Multiple Reference Frames (MRF) and Sliding Mesh Interface (SMI) numerical techniques. The differences between the two techniques are quantified. It is then followed by a detailed comparison of the turbine's power/thrust output and the associated wake development at three tip speeds ratios (λ = 3, 6, 10). The phenomenon of blockage effect and spatial features of the flow are explained and linked to the turbines power output. Validation of wake profiles patterns at multiple locations downstream is also performed at each λ. The present work aims to evaluate the potential of the numerical methods in reproducing wind tunnel experimental results such that the method can be applied to full-scale turbines operating under realistic conditions in which observation data is scarce or lacking.

회전로터 및 후류 동하중을 고려한 스마트 무인기 천이응답해석 (Transient Response Analysis for a Smart UAV Considering Dynamic Loads by Rotating Rotor and Wakes)

  • 김현정;김동현;오세원;김성준;최익현;김태욱;이상욱;김진원;이정진
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2006년도 춘계학술대회논문집
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    • pp.367-375
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    • 2006
  • In this study, structural vibration analyses of a smart unmanned aerial vehicle (UAV) have been conducted considering dynamic loads generated by rotating rotor and wakes. The present UAV (TR-S5-03) finite element model is constructed as a full three-dimensional configuration with different fuel conditions and tilting angles for helicopter, transition and airplane flight modes. Practical computational procedure for modal transient response analysis (MTRA) is established. using general purpose finite element method (FEM) and computational fluid dynamics (CFD) technique. The dynamic loads generated by rotating blades in the transient and forward flight conditions are calculated by unsteady CFD technique with sliding mesh concept. As the results of present study, transient structural displacements and accelerations are presented in detail. In addition, vibration characteristics of structural parts and installed equipments are investigated for different fuel conditions and tilting angles.

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중형 컨테이너선의 연료절감형 비틀림 타 개발 (Development of Twisted Rudder to Reduce Fuel Oil Consumption for Medium Size Container Ship)

  • 전호환;차경정;이인원;최정은
    • 대한조선학회논문집
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    • 제55권2호
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    • pp.169-177
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    • 2018
  • Twisted rudder, twisted rudder with bulb, and twisted rudder with bulb and fin have been developed computationally for 3,000 TEU container ship through parametric study. The objective function is to minimize delivered power in model scale. Design variables are twisted angle, rudder bulb diameter and fin angle. The governing equation is Reynolds averaged Navier-Stokes equations in an unsteady turbulent flow and the Reynolds stress model applied for the turbulent closure. A double body model is used for the treatment of free-surface. The calculation was carried out in towing and self-propulsion conditions at design speed. The sliding mesh technique was employed to simulate the flow around the propeller. Form factor is obtained from the towing computation. Self-propulsion point is obtained from the self-propelled computations at two propeller rotating speeds. The delivered power due to the designed twisted rudder, twisted rudder with bulb, and twisted rudder with bulb and fin are reduced by 1.1%, 1.6%, and 2.0%, respectively.

에어컨 실외기 토출그릴 형상 최적화 (A Study on the Optimization of Discharge Grille of Outdoor Unit of Air Conditioner)

  • 최석호;오세기;김현종;진근호;오시영;김병순
    • 설비공학논문집
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    • 제23권11호
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    • pp.726-732
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    • 2011
  • The aerodynamic and aeroacoustic performance of discharge grille of outdoor unit of air-conditioner was investigated in this study. Discharge grille is one of outdoor unit's important parts to affect the flow rate and Overall Sound Pressure Level(OSPL). New type of discharge grille was suggested based on the results of numerical simulation. To simulate the flow pattern near the propeller fan, commercial flow solver FLUENT was used. Sliding mesh method was used for rotating propeller fan and initial condition for unsteady model was calculated by Multiple Reference Frame(MRF) method. To minimize the interaction noise between fan blade wake and discharge grille, new discharge grille has radial rib which is aligned with trailing edge of fan blade. And inclined radial rib was adopted for reducing flow rate drop in discharge grille. The optimization of inclined angle of radial grille was performed experimentally.

Simulation of fracture in plain concrete modeled as a composite material

  • Bui, Thanh T.;Attard, Mario M.
    • Computers and Concrete
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    • 제2권6호
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    • pp.499-516
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    • 2005
  • A composite model is used to represent the heterogeneity of plain concrete consisting of coarse aggregates, mortar matrix and the mortar-aggregate interface. The composite elements of plain concrete are modeled using triangular finite element units which have six interface nodes along the sides. Fracture is captured through a constitutive single branch softening-fracture law at the interface nodes, which bounds the elastic domain inside each triangular unit. The inelastic displacement at an interface node represents the crack opening or sliding displacement and is conjugate to the internodal force. The path-dependent softening behaviour is developed within a quasi-prescribed displacement control formulation. The crack profile is restricted to the interface boundaries of the defined mesh. No re-meshing is carried out. Solutions to the rate formulation are obtained using a mathematical programming procedure in the form of a linear complementary problem. An event by event solution strategy is adopted to eliminate solutions with simultaneous formation of softening zones in symmetric problems. The composite plain concrete model is compared to experimental results for the tensile crack growth in a Brazilian test and three-point bending tests on different sized specimens. The model is also used to simulate wedge-type shear-compression failure directly under the loading platen of a Brazilian test.

Twisted rudder for reducing fuel-oil consumption

  • Kim, Jung-Hun;Choi, Jung-Eun;Choi, Bong-Jun;Chung, Seok-Ho
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제6권3호
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    • pp.715-722
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    • 2014
  • Three twisted rudders fit for large container ships have been developed; 1) the Z-twisted rudder that is an asymmetry type taking into consideration incoming flow angles of the propeller slipstream, 2) the ZB-twisted rudder with a rudder bulb added onto the Z-twisted rudder, and 3) the ZB-F twisted rudder with a rudder fin attached to the ZB-twisted rudder. The twisted rudders have been designed computationally with the hydrodynamic characteristics in a self-propulsion condition in mind. The governing equation is the Navier-Stokes equations in an unsteady turbulent flow. The turbulence model applied is the Reynolds stress. The calculation was carried out in towing and self-propulsion conditions. The sliding mesh technique was employed to simulate the flow around the propeller. The speed performances of the ship with the twisted rudders were verified through model tests in a towing tank. The twisted versions showed greater performance driven by increased hull efficiency from less thrust deduction fraction and more effective wake fraction and decreased propeller rotating speed.