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Volume 1997 (1997)
- Issue 73 Pages 3-
- Issue 72 Pages 1-
- Issue 71 Pages 1-
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Volume 1997, Issue 72
Displaying 1-8 of 8 articles from this issue
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Masashi HARADA, Yoshinori OKUNO1997 Volume 1997 Issue 72 Pages 1-9
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSFlight simulation tests of a fire helicopter for high buildings are conducted under the cooperative research between the National Aerospace Laboratory and the Tokyo Fire Department. One of the most important factors to realize a fire helicopter is the heavily turbulent wind around buildings which may adversely affect the safety and efficiency during fire fighting. In simulating the mission of the fire helicopter, it is required to generate the wind in real time depending on both time and location of the measuring point. When the height of the building is assumed to be infinite, it is feasible to make such wind by using two dimensional discrete vortex method. It is also shown that this method is applicable to the building whose height is not so longer than its width.View full abstractDownload PDF (2344K) -
Part 2 Statistical Properties of Fluctuating PressuresYasushi UEMATSU, Nicholas ISYUMOV1997 Volume 1997 Issue 72 Pages 11-19
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSThe characteristics and structures of the pressure fields on the roof and wall edges of a low-rise building with a 4: 12-pitched roof have been investigated by using a data-base, which was constructed at BLWTL, The University of Western Ontario. Detailed analyses of the data are made for one specific wind direction, i.e. the worst wind direction, for each surface of the building. This paper presents the results on the statistical properties of the fluctuating pressures; that is, the probability density function, level-crossing rate, peak factor etc. The time-space correlation of the pressure fluctuations is discussed based on the spectral analysis. Quantitative descriptions for various aerodynamic parameters are provided.View full abstractDownload PDF (2109K) -
Yan MENG, Kazuki HIBI1997 Volume 1997 Issue 72 Pages 21-34
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSA wind tunnel experiment has been performed to investigate turbulence characteristics and organized motions on the flat roof of a high-rise building. Three velocity components were measured with split- fiber probes designed for measuring flows with a high turbulence intensity and separation. Flow patterns on the roof were also studied by means of flow visualization technique with a laser sheet. In the race of flow normal to a face (α=0°), vortices shed at the windward edge generate a low mean velocity and high turbulence near the roof. The longitudinal distance between the vortices is estimated to be 0.6b and their frequency is about Uoh/b, where Uoh is the approaching velocity at the roof height and b is the width of the building. In the case α=45° conical vortices on the roof cause a low mean velocity and high turbulence near the axes of vortices, and a high mean velocity between them. The spectra of three velocity components suggest that high turbulence energies on the roof are not only generated by a high frequency motion corresponding to the vortex shedding at windward edges of the roof, but also by a low frequency motion, which has a period as same as that of Kerman type vortex in the building wake. Vertical profiles of mean and standard deviation of the three velocity components, as well as spectra of them, are presented and compared with those of approaching flow for the two cases.View full abstractDownload PDF (3359K) -
Minoru MAKINO1997 Volume 1997 Issue 72 Pages 35-45
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSStrong winds due to typhoons are dominant for building design in the Japanese Isles. Basic design wind speeds for typhoon winds are given as a map over the Japanese Isles in friction free gradient wind. The map is prepared by indirect probabilistic procedure based on statistical properties of typhoons which struck the Japanese Isles for 20 years from 1950. This period was the most active in recent years.
Estimated wind speeds from observed annual maximum typhoon wind speeds at 10m above the ground are compared to those of this analysis at 140 weather stations for the same period. The conversion factors from the friction free winds to the surface ones are seemed to be natural than the factors depending on the surface roughness around the weather stations.View full abstractDownload PDF (2485K) -
Part 1 Mean and Fluctuating Pressure CoefficientYoshinobu KUBO, Yuji NIIHARA, Ryuji NAKANO, Koji HAYASHIDA1997 Volume 1997 Issue 72 Pages 47-58
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSThough concrete cable-stayed bridges have been accepted to have an aerodynamic advantage, the recent remarkable development of concrete cable- stayed bridges requires wind tunnel tests to investigate the aerodynamic stability. However, there are few studies that compare the phenomenon observed by wind tunnel tests and by full scale measurements, especially wind pressure.
In this study, the wind pressure acting on a deck of a concrete cable-stayed bridge measured by full scale measurement and wind tunnel test is investigated . The bridge described here is IKARA Bridge that is the longest concrete cable-stayed bridge in Japan . First the angle of attack of an approaching wind at the bridge is compensated by a wind tunnel test . Then it was shown that the measured mean and fluctuating pressure are largely effected by the angle of attack and the turbulent intensity, respectively. Finally the flow pattern around the actual deck of the concrete cable stayed bridge was presumed.View full abstractDownload PDF (3175K) -
Three Dimensional Simulation Model of Atmosphere and Ocean Part 1Kenji TAKAGI, Motohiko YAMADA, Yasushi UEMATSU1997 Volume 1997 Issue 72 Pages 59-72
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSWe provide three tests analytically and numerically in terms of the 3- dimensional simulation model of local wind. These tests are to examine a) two differential methods for linear terms. b) four differential methods and two time marching methods for the advection term and c) five turbulent models for the vertical transportation in the basic equations of atmosphere motion. From these testa we conclude that a) the 4th order central difference method can be the most suitable for calculating linear terms, b) the Matsuno scheme, which is a kind of implicit method, and the 4th order central differential method can be the most suitable for calculating the advection term and c) the level 2.5 model combined with the transfer equation of the q2l can be the most suitable for the meso γA scale problem under consideration.View full abstractDownload PDF (3451K) -
Yasushi MITSUTA, Takeshi FUJII1997 Volume 1997 Issue 72 Pages 73-91
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSA scheme for the prediction of typhoon wind damages is proposed. A typhoonpressure profile model was reduced from the objective analysis of the past severe typhoons hitting Japanese Islands. Simple formula to compute the gradient wind speed distribution of the moving typhoon and the method for the reduction of the gradient wind into the basic surface wind are proposed. Combining the above knowledges with the experienced wind damages to wind speed relationship during Typhoon 9119 Mireille passage. a new scheme predicting typhoon wind damages has been established.View full abstractDownload PDF (4731K) -
Kazuo TAMURA1997 Volume 1997 Issue 72 Pages 93-98
Published: July 31, 1997
Released on J-STAGE: September 28, 2010
JOURNAL FREE ACCESSDownload PDF (1848K)
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