Wind Engineers, JAWE
Online ISSN : 1883-8413
Print ISSN : 0912-1935
ISSN-L : 0912-1935
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Volume 1998, Issue 74
Displaying 1-7 of 7 articles from this issue
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  • Fuzzy Prediction System for Wind Speed and Wind Direction in Typhoon Area using Real-time Data
    Kiyoshi SANO, Takuya KAMANO, Takashi YASUNO, Takayuki SUZUKI, Takayuki ...
    1998 Volume 1998 Issue 74 Pages 5-14
    Published: January 31, 1998
    Released on J-STAGE: September 28, 2010
    DOIhttps://doi.org/10.5359/jawe.1998.5
    JOURNAL FREE ACCESS
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    This paper describes the use of a self-tuning fuzzy prediction algorithm for wind speed and wind direction in typhoon area. The wind speed and wind direction have been measured by an anemovane on the top of a power-transmission tower. First, the fuzzy prediction rules are adjusted by a tuning algorithm so that the estimated data agree with the measured data for the past typhoon. After tuning process is completed, the wind speed and wind direction for a different typhoon are predicted by using the tuned fuzzy rules and the current data. Simulation results demonstrate the effectiveness of the proposed system.
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  • The characteristics of wind forces acting on an equilateral triangular prism
    Hiroaki NISHIMURA
    1998 Volume 1998 Issue 74 Pages 15-24
    Published: January 31, 1998
    Released on J-STAGE: September 28, 2010
    DOIhttps://doi.org/10.5359/jawe.1998.15
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    A triangular prism has a particular cross-sectional shape in the point of view of the aerodynamic lift force which acts on it in winds; in case that one face of a triangular prism is normal to the approaching flow direction, if the face is facing leeward, the lift force on the prism is not affected by Kerman vortices, but on the contrary, if the face is facing windward, the lift force on the prism is strongly affected by Karmen vortices.
    These phenomena are related to the “after-body” in the wake region: in the former case, the prism has no after-body, and in the latter case, the prism has a volume of after-body in the wake region. The aerodynamic fortes acting on the after-body contribute to the galloping phenomenon, too.
    In this paper, effects of the after-body on the characteristics of lift force fluctuation and aerodynamic transverse oscillation are described, based on a series of wind tunnel experiments on a three- dimensional triangular prism.
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  • Development of Traversing System for Anemometer Using Parallel Type Wire Driven Mechanism
    Won CHOE, Yoshikage UCHIKURA, Sadao KAWAMURA, Hiroshi KOBAYASHI
    1998 Volume 1998 Issue 74 Pages 25-33
    Published: January 31, 1998
    Released on J-STAGE: September 28, 2010
    DOIhttps://doi.org/10.5359/jawe.1998.25
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    For anemometers in wind tunnels, high speed and high precision motions are strongly required. In this view point, we develop a new type of effective traversing system for anemometer by using parallel wire driven mechanism. In the developed system, several wires are utilized to move an anemometer instead of serial link structure. Since the mass of wire is very small, relatively small actuators can be used. Moreover, an influence on the wind flow from the measurement system is able to be reduced because the diameter of wires is very small (1 [mm]). However, the vibration will occur due to the low stiffness of wires. To evaluate the performance of the developed system, positioning tests are performed without wind blowing by using proto type of anemometer system. Moreover, some experiments are also performed in the boundary layer of a wind tunnel in order to measure the real wind velocity. Through experimental results, effectiveness of this system is demonstrated.
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  • Influence of Turbulence Characteristics on Statistical Quantities at an Inlet Boundary for LES of a Turbulent Boundary Layer
    Takashi MARUYAMA
    1998 Volume 1998 Issue 74 Pages 35-45
    Published: January 31, 1998
    Released on J-STAGE: September 28, 2010
    DOIhttps://doi.org/10.5359/jawe.1998.35
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    A method of numerical generation of wind fluctuations was reviewed. According to its procedure a series of inflow wind fluctuations were artificially generated as inlet boundary conditions. Using these signals a turbulent boundary layer at high Reynolds number developed over a rough surface was calculated by Large Eddy Simulation. Numerical simulations were carried out using some inflows which had different characteristics on statistical quantities and the influence of turbulence characteristics were examined. In order to reproduce appropriate mean flow field, the generated and the experimental wind fluctuations should be equivalent in statistical property, i.e. the mean value, the variance and the power spectrum density. The realization of spatially correlated fluctuation of three wind components will lead the simulation to more realistic results.
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  • The mechanism of the occurrence for the fluctuating force on a stationary two-dimensional circular cylinder
    Hiroaki NISHIMURA, Yoshihito TANIIKE
    1998 Volume 1998 Issue 74 Pages 47-57
    Published: January 31, 1998
    Released on J-STAGE: September 28, 2010
    DOIhttps://doi.org/10.5359/jawe.1998.47
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    It is well known that the fluctuating pressures induced by the shedding of the Karman vortex on a stationary circular cylinder yield the periodic lift force, especially in a sub-critical Reynolds number. The Karmen vortex is formed away from the cylinder, so that the Karman vortex dose not seem to have direct effects upon the fluctuating pressures on the side surfaces of the cylinder.
    In this study, we investigated the mechanism of the occurrence for the periodic force on a circular cylinder in a range of the sub-critical Reynolds number, by using the simultaneous multi-pressure measuring system and the flow visualization technique. It is found that not the shed Karman vortex itself but the movement of separated shear layers, which are formed nearby side surfaces of the cylinder and affected by the Karman vortex shedding, directly contribute to the fluctuating pressures on the cylinder. It is found that the fluctuations of the stagnation point and the separation point on the cylinder are synchronized with the lift fluctuation, both of which have the same frequency as the Strouhal number. We also clarified the relationship between the shedding of the Karman vortex, the movement of the separated shear layer and the occurrence of the fluctuating pressures on the circular cylinder.
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  • Damages by a high wind in the northern and central Kyushu on October 14, 1997
    Taiichi HAYASHI, Takashi MARUYAMA, Yoshihito TANIIKE, Hiroaki NISHIMUR ...
    1998 Volume 1998 Issue 74 Pages 59-64
    Published: January 31, 1998
    Released on J-STAGE: September 28, 2010
    DOIhttps://doi.org/10.5359/jawe.1998.59
    JOURNAL FREE ACCESS
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  • Wind Generation in the World
    Hikaru Matsumiya
    1998 Volume 1998 Issue 74 Pages 69-74
    Published: January 31, 1998
    Released on J-STAGE: September 28, 2010
    DOIhttps://doi.org/10.5359/jawe.1998.69
    JOURNAL FREE ACCESS
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