• Title, Summary, Keyword: wind tunnels

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Will CFD ever Replace Wind Tunnels for Building Wind Simulations?

  • Phillips, Duncan A.;Soligo, Michael J.
    • International Journal of High-Rise Buildings
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    • v.8 no.2
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    • pp.107-116
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    • 2019
  • The use of computational fluid dynamics (CFD) is becoming an increasingly popular means to model wind flows in and around buildings. The first published application of CFD to both indoor and outdoor building airflows was in the 1970's. Since then, CFD usage has expanded to include different aspects of building design. Wind tunnel testing (WTT) on buildings for wind loads goes back as far as 1908. Gustave Eiffel built a pair of wind tunnels in 1908 and 1912. Using these he published wind loads on an aircraft hangar in 1919 as cited in Hoerner (1965 - page 74). The second of these wind tunnels is still in use today for tests including building design ($Damljanovi{\acute{c}}$, 2012). The Empire State Building was tested in 1933 in smooth flow - see Baskaran (1993). The World Trade Center Twin Towers in New York City were wind tunnel tested in the mid-sixties for both wind loads, at Colorado State University (CSU) and the [US] National Physical Laboratory (NPL), as well as pedestrian level winds (PLW) at the University of Western Ontario (UWO) - Baskaran (1993). Since then, the understanding of the planetary boundary layer, recognition of the structures of turbulent wakes, instrumentation, methodologies and analysis have been continuously refined. There is a drive to replace WTT with computational methods, with the rationale that CFD is quicker, less expensive and gives more information and control to the architects. However, there is little information available to building owners and architects on the limitations of CFD for flows around buildings and communities. Hence building owners, developers, engineers and architects are not aware of the risks they incur by using CFD for different studies, traditionally conducted using wind tunnels. This paper will explain what needs to happen for CFD to replace wind tunnels. Ultimately, we anticipate the reader will come to the same conclusion that we have drawn: both WTT and CFD will continue to play important roles in building and infrastructure design. The most pressing challenge for the design and engineering community is to understand the strengths and limitations of each tool so that they can leverage and exploit the benefits that each offers while adhering to our moral and professional obligation to hold paramount the safety, health, and welfare of the public.

Computational study of road tunnel exposure to severe wind conditions

  • Muhic, Simon;Mazej, Mitja
    • Wind and Structures
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    • v.19 no.2
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    • pp.185-197
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    • 2014
  • Ventilation and fire safety design in road tunnels are one of the most complex issues that need to be carefully considered and analysed in the designing stage of any potential upgrade of ventilation and other fire safety systems in tunnels. Placement road tunnels space has an important influence on fire safety, especially when considering the effect of adverse wind conditions that significantly influence ventilation characteristics. The appropriate analysis of fire and smoke control is almost impossible without the use of modern simulation tools (e.g., CFD) due to a large number of influential parameters and consequently extensive data. The impact of the strong wind is briefly presented in this paper in the case of a longitudinally ventilated road tunnel Kastelec, which is exposed to various severe wind conditions that significantly influence its fire safety. The possibility of using CFD simulations in the analysis of the tunnel placement in space terms negative effect of wind influence on the tunnel ventilation is clearly indicated.

Application of CFD to Design Atmospheric Boundary Layer Wind Tunnel (지상 경계층 풍동 설계를 위한 CFD의 적용)

  • Chang Byeong-Hee
    • 한국전산유체공학회:학술대회논문집
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    • pp.37-43
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    • 2001
  • The methods of atmospheric boundary layer generation in test section were reviewed. To utilize conventional aerodynamic wind tunnels as atmospheric wind tunnels, boundary layer growth should be accelerated. To achieve this, improvement of boundary layer generation devices is required and it might be done by CFD. In this respect, CFD application cases in boundary generation devices were reviewed and potential areas were considered. Some cases are tried by Fluent 5 code.

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A comprehensive high Reynolds number effects simulation method for wind pressures on cooling tower models

  • Cheng, X.X.;Zhao, L.;Ge, Y.J.;Dong, J.;Demartino, C.
    • Wind and Structures
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    • v.24 no.2
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    • pp.119-144
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    • 2017
  • The traditional method for the simulation of high Reynolds number (Re) effects on wind loads on cooling tower models in wind tunnels focuses only on the mean wind pressure distribution. Based on observed effects of some key factors on static/dynamic flow characteristics around cooling towers, the study reported in this paper describes a comprehensive simulation method using both mean and fluctuating wind pressure distributions at high Re as simulation targets, which is indispensable for obtaining the complete full-scale wind effects in wind tunnels. After being presented in this paper using a case study, the proposed method is examined by comparing the full covariance matrices and the cross-spectral densities of the simulated cases with those of the full-scale case. Besides, the cooling tower's dynamic structural responses obtained using the simulated wind pressure fields are compared with those obtained by using the full-scale one. Through these works, the applicability and superiority of the proposed method is validated.

Low Speed Wind Tunnel Testing to Measure Drag with Velocity Variation on a Cube Body

  • Rahmanto, R. Hengki;Choe, Gwang-Hwan;Go, Dong-Gyun
    • 한국태양에너지학회:학술대회논문집
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    • pp.96-102
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    • 2008
  • For centuries now, wind tunnels have been a key element in scientific research in a number of fields. Experimenting with racecars, airplanes, weather patterns, birds, and various other areas has been made much easier because of its development. In the racing field, for example, the information gathered from this testing can mean the difference between winning and losing a race. Weather simulations can also provide valuable information regarding building stability and safety. This has become very important when designing buildings today. Valuable information concerning bird flight has also been collected based on wind tunnel testing. Wind tunnels have a variety of important uses in the world today. Wind tunnel that used here is an open loop low speed wind tunnel. The fundamental principles of this tunnel is moving the air using exhaust fan In the rear side, and placing the cube in the external balance system which used to measure the working force. This experiment is using 50mm cube of finished wood. From this experiment we can get Drag Force (FD), The Reynolds Number (Re) and The Coefficient of Brae (CD).

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Time-Dependent Characteristics of the Nonequilibrium Condensation in Subsonic Flows

  • Baek, Seung-Cheol;Kwon, Soon-Bum;Toshiaki Setoguchi;Kim, Heuy-Dong
    • Journal of Mechanical Science and Technology
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    • v.16 no.11
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    • pp.1511-1521
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    • 2002
  • High-speed moist air or steam flow has long been of important subject in engineering and industrial applications. Of many complicated gas dynamics problems involved in moist air flows, the most challenging task is to understand the nonequilibrium condensation phenomenon when the moist air rapidly expands through a flow device. Many theoretical and experimental studies using supersonic wind tunnels have devoted to the understanding of the nonequilibrium condensation flow physics so far. However, the nonequilibrium condensation can be also generated in the subsonic flows induced by the unsteady expansion waves in shock tube. The major flow physics of the nonequilibrium condensation in this application may be different from those obtained in the supersonic wind tunnels. In the current study, the nonequilibrium condensation phenomenon caused by the unsteady expansion waves in a shock tube is analyzed by using the two-dimensional, unsteady, Navier-Stokes equations, which are fully coupled with a droplet growth equation. The third-order TVD MUSCL scheme is applied to solve the governing equation systems. The computational results are compared with the previous experimental data. The time-dependent behavior of nonequilibrium condensation of moist air in shock tube is investigated in details. The results show that the major characteristics of the nonequilibrium condensation phenomenon in shock tube are very different from those in the supersonic wind tunnels.

Development of Tunnel-Environment Monitoring System and Its Installation I -Monitoring System and Measurement in Subway Tunnel- (터널 환경측정 시스템 개발 및 측정 I -개발 시스템 및 지하철터널 측정-)

  • Park, Won-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.12
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    • pp.8608-8615
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    • 2015
  • We developed a system that can collect and transmit real-time environmental data such as temperature, humidity, wind direction, and wind speed, and equipment performing aging tests on fire detectors. This system was installed in three representative sites of railway tunnels in South Korea such as Gumjung, Solan, Seoul Subway Line 4 tunnels. The systems showed a stable performance and collected environmental data for over a year. We analyzed environmental data collected by two of our developed systems installed in the running tunnels of Gwacheon Line of Seoul Subway Line 4. The developed system was capable of safely analyzing tunnel environments for 24 h straight using a wireless communication network, and has potential for use in a variety of fields other than tunnels.

UNSTEADY WALL INTERFERENCE EFFECT ON FLOWS AROUND AN OSCILLATING AIRFOIL IN CLOSED TEST-SECTION WIND TUNNELS (폐쇄형 풍동 시험부내의 진동하는 익형 주위 유동에 대한 비정상 벽면효과 연구)

  • Kang Seung-Hee;Kwon Oh Joon;Hong Seung-Kyu
    • Journal of computational fluids engineering
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    • v.10 no.2
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    • pp.60-68
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    • 2005
  • For study on the unsteady wall interference effect, flows around a forced oscillating airfoil in closed test-section wind tunnels have been numerically investigated by solving compressible Navier-Stokes equations. The numerical scheme is based on a node-based finite-volume method with the Roe's flux-difference splitting and an implicit time-integration method coupled with dual time-step sub-iteration. The Spalart-Allmaras one-equation model is employed for the turbulence effect. The computed results of the oscillating airfoil having a thin wake showed that the lift curve slope is increased and the magnitude of hysteresis loop is reduced by the interference effects. Since the vortex around the airfoil is generated and convected downstream faster than the free-air condition, the phase of lift, drag and pitching moment coefficients was shifted. The pressure on the test section wall shows harmonic terms having the oscillating frequency contained in the wail effect.

A Study on PM10 Control in Subway Tunnels Using Natural Polysaccharide Dust Collecting Agent (천연 다당류 먼지포집제를 이용한 지하철 터널 내 PM10 제어에 대한 연구)

  • Lee, Han-Seob;Hwang, Su-Jin;Hwang, Hyun-Seok
    • Journal of Environmental Health Sciences
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    • v.43 no.2
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    • pp.122-129
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    • 2017
  • Objectives: Most of the $PM_{10}$ in subway stations is spread by the train-induced wind from the tunnels. Therefore, in order to improve air quality in subway stations, it is important to remove the $PM_{10}$ from the tunnels. After the installation of PSD (platform screen doors), the influence of train-induced wind and $PM_{10}$ at the platform has decreased, but is estimated to have increased in subway tunnels. This study was conducted to investigate the control of $PM_{10}$ in subway tunnels by applying a 500-fold diluted solution mixed with a humectant using a natural polymer. Methods: For this purpose, we tested the dust reduction effect in a laboratory and corrosion test and water pollution using fish and aquatic plants for the natural dust collecting agent. In the tunnel of a subway station, we used the natural dust collecting agent over 15 days. The study was carried out on $PM_{10}$ control during operation, which accounts for more than 70% of subway dust. Results: As results, the natural dust collecting agent exhibited an excellent dust control effect, and it was safe for water quality and soil. It showed the effect of controlling $PM_{10}$ in the subway tunnel by 49.5- 64.7% over 15 days. The use of the dust collecting agent for the control of $PM_{10}$ could be confirmed in the subway. Conclusion: It is necessary to clearly explain the major portions of chemical components contained in $PM_{10}$ to figure out the characteristics of $PM_{10}$ and to develop effective reduction measures to decrease the adverse effects of $PM_{10}$ in the subway.

A Study on the Reduction of Pulsations in a 3/4 Open Jet Wind Tunnel (3/4 Open Jet 실차풍동에서의 Pulsation 감소에 관한 연구)

  • Kim Moo-Sang;Kee Jung-Do;Lee Jung-Ho;Jang Jin-Hyuk
    • Proceedings of the KSME Conference
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    • pp.839-842
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    • 2002
  • Some open jet wind tunnels have been operating under limitations due to large pressure fluctuations at some wind tunnel speeds. The Hyundai Aero-acoustic full scale Wind Tunnel (HAWT), which was completed in 1999, shows that most of the specifications were fulfilled but wind tunnel pulsations at some wind speeds were observed. Hyundai Motor Company started the wind tunnel modification in order to solve this problem in 2001. After the modification work the amplitude of pressure fluctuation was reduced and below required level over full wind speed range. Aero-acoustic performance, e.g. background noise, as well as aerodynamic performance were improved after this work.

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