【０００１】
【発明の属する技術分野】
本発明の風圧測定方法は、建物に加わる風荷重を推定するための風洞実験において、建物模型に設けられた風圧測定孔に生じる風圧の測定方法に関する。
【０００２】
【従来の技術】
建物に加わる風荷重の予測は、建物の縮尺模型を用いる風洞実験によるのが一般的である。建物に加わる風荷重は、建物全体に加わる荷重と壁面の部材に加わる風圧とに分けられる。建物全体の荷重は天秤を用いて測定され、壁面の風圧は圧力計を用いて行われる。また、壁面に加わる風圧を元に、建物全体に加わる荷重の算定を行う方法が、特許文献１に示されている。
【０００３】
壁面風圧の風洞実験は、建物の壁面に加わる風荷重を風洞実験により推定するために行われる。風洞実験によって推定された風荷重は、主に、建物に用いる部材に要求される設計強度を決定するために用いられる。
【０００４】
壁面風圧の風洞実験は、図１に示すように、建物の縮尺模型１を用い、該縮尺模型１の壁面に、風圧を測定するための風圧測定孔３を設けて行われる。風圧測定孔に生じる風圧は、プラスチック製のフレキシブルなチューブ２を介して圧力計５に導かれる。縮尺模型に設ける風圧測定孔は、建物の規模や風洞実験の規模にもよるが、数百点程度である。
【０００５】
圧力計５の性能が向上して、微圧や高周波で変動する圧力の測定が可能となり、また、小型で高性能のコンピューター７の出現により、大容量のデータ処理が行えるようになった。
【０００６】
このため、風洞実験において、風圧の変動が精度よく測定されるようになり、測定された風圧は、平均風圧と変動値に分けて解析され、風圧の変動に対する建物や外装材の応答が検討されるようになった。
【０００７】
風洞実験において、風圧測定孔３に加わる風圧を正確に測定するには、圧力計５を風圧測定孔３に直接設けるのが最も好ましいが、ほとんどの風洞実験において、風圧測定孔３の間隔は狭く、圧力計５を風圧測定孔５に直接設置することは困難である。このため、風圧測定孔３と圧力計５をフレキシブルなチューブ２で繋ぎ、風圧測定孔３に加わる風圧を該チューブで圧力計５に伝達する。
【０００８】
さらに、数百点もある風圧測定孔３の全てに圧力計５を繋ぐことは、一定の測定時間を必要とする変動風圧の測定において、圧力計５のドリフトの校正が大変であり、また測定システムが高価なものとなるので、図２に示すように風圧測定孔３と圧力計５を繋ぐチューブの間に測定孔切り替え器４を設け、測定する風圧測定孔を順次切り替えして、１台の圧力計で多数の風圧測定孔３の圧力を測定できるようにし、数台乃至数十台の圧力計で数百点以上の多数の風圧測定孔の風圧を測定する方法がある。
【０００９】
このような風圧測定孔と圧力計とをチューブと測定孔切り替え器で繋いで行う風圧の測定において、チューブや測定孔切り替え器は圧力変動の高周波成分を減衰し、位相のズレ（位相差）を生じさせる。そのため、風圧の変動を正しく評価するためには、減衰や位相差を補正する必要がある。
【００１０】
減衰および位相差の補正値は、図３に示す測定により求められている。信号発生器９でホワイトノイズの信号を発生させ、ホワイトノイズの信号を遮音箱１１の中に置かれたスピーカー１０を用いて圧力に変える。ホワイトノイズの信号は、広範囲の周波数域での圧力変動となる。圧力測定孔１２、１２’が設けられている平板１３は、遮音箱１１の中を仕切るように設置され、圧力測定孔１２’には、平板１３に直付けされている圧力計５’で圧力変動を測定し、測定値Ａを得る。圧力測定孔１２には、風洞実験で用いるチューブと測定孔切り替え器を繋ぎ、圧力変動を圧力計５で測定し、測定値Ｂを得る。
【００１１】
測定値Ａと測定値Ｂの測定は同時に行い、測定結果をそれぞれフーリエ変換し、圧力変動の周波数毎の圧力の大きさと位相とを求める。周波数毎の圧力の大きさと位相を測定値Ａと測定値Ｂとで比較し、圧力の大きさの比を減衰、位相のズレを位相差とする。
【００１２】
減衰と位相の遅れは、風圧変動の周波数範囲として知られている１０Ｈｚ〜２００Ｈｚの範囲で求めておく。
【００１３】
さらに、減衰と位相の遅れは、風洞実験で測定される圧力の時系列のデータを、フーリエ変換し、周波数毎の圧力の大きさを求め、前述の減衰と位相差を用いて補正を行い、風洞実験の風圧測定結果とする。
【００１４】
補正を正しく行うために、風壁面風圧の測定は、信号発生器とスピーカーを用いて減衰と位相差を求めたのと同じ性能の圧力計、測定孔切り替え器を用い、さらに、同じ材質、同じ長さ、同じ太さのチューブを用いて行われる。
【００１５】
【特許文献１】
特開平６−５０８３９号公報
【００１６】
【発明が解決しようとする課題】
測定孔切り替え器を用いて風圧を測定する場合、２５０Ｈｚ以上の変動圧力は減衰が８５％以上であり、従来の補正では誤差が大きく、信頼できる測定結果を得ることが困難であった。また、１ｋＨｚ以上の高周波領域でも応答可能な圧力計を用いると、安定性が悪く長時間の測定が困難であった。
【００１７】
【課題を解決するための手段】
本発明の風圧測定方法は、風洞内に風圧測定孔が設けてある建物模型を設置し、該風圧測定孔に加わる風圧をチューブと測定孔切り替え器で圧力計に導き、建物模型に加わる風圧を測定する風圧測定方法において、最大応答周波数ｆｐが３００Ｈｚ〜５００Ｈｚの圧力計を用い、信号発生器とスピーカーとを用いてホワイトノイズの信号による圧力変動を発生させ、該圧力変動を該圧力計で１／（２ｆｐ）の時間間隔で測定し、チューブと測定港切り替え器とによって生じる風圧の振幅および位相の補正値を求め、該補正値を建物模型の風圧測定孔に加わる風圧の補正に用いることを特徴とする風圧測定方法である。
【００１８】
【発明の実施の形態】
壁面風圧の測定に用いられる模型に設けられている風圧測定孔と圧力切替器とを繋ぐチューブの長さは、チューブの長さによって変動成分の減衰する大きさが異なるため、全ての圧力測定孔に一定の長さに揃えたチューブを用いることが望ましい。
【００１９】
チューブは長いほど圧力の減衰が大きいので、できる限り短くすることが好ましいが、建物模型の形により、一定の長さに揃えられないときは、チューブの長さ毎の補正値を求めておけばよい。
【００２０】
風洞実験において、変動成分を評価するのは、２００Ｈｚ以下なので、圧力計の最大応答周波数ｆｐは、２００Ｈｚ以上とすることが好ましい。より好ましくは、高周波成分の精度を十分に確保するため、最大応答周波数ｆｐは、３００Ｈｚ以上とすることが望ましい。
【００２１】
また、最大応答周波数ｆｐが高くなると、ゼロドリフトのため長時間の安定した測定が困難となるので、ｆｐは５００Ｈｚ以下とすることが好ましい。
【００２２】
減衰および位相差の補正値は、図３に示す装置を用いて求める。信号発生器９でホワイトノイズの信号を発生させ、ホワイトノイズの信号を遮音箱１１の中に置かれたスピーカー１０を用いて圧力に変える。ホワイトノイズの信号は、１０００Ｈｚまでの周波数域の信号とすることが好ましい。
【００２３】
圧力測定孔１２、１２’が設けられている平板１３は、遮音箱１１の中を仕切るように設置され、圧力測定孔１２’には、平板１３に直付けされている圧力計５’で圧力変動を測定し、測定値Ａを得る。圧力測定孔１２には、風洞実験で用いるチューブと測定孔切り替え器を繋ぎ、圧力変動を圧力計５で測定し、測定値Ｂを得る。測定する時間間隔は圧力計の最大応答周波数ｆｐに対した１／（２ｆｐ）とすることが、２００Ｈｚ付近の高周波成分を精度良く補正できるので、望ましい。
【００２４】
測定値Ａと測定値Ｂの測定は同時に行い、測定結果をそれぞれフーリエ変換し、圧力変動の周波数毎の圧力の大きさと位相とを求める。周波数毎の圧力の大きさと位相を測定値Ａと測定値Ｂとで比較し、圧力の大きさの比を減衰に対する補正値、位相のズレを位相に対する補正値とする。
【００２５】
減衰と位相に対する補正値は、風圧変動の周波数範囲として知られている１０Ｈｚ〜２００Ｈｚの範囲で求めておくことが好ましい。
【００２６】
さらに、減衰と位相の補正は、風洞実験で測定される風圧の時系列のデータをフーリエ変換し、周波数毎の風圧の大きさを求め、補正を行い、風洞実験の風圧測定結果とする。
【００２７】
補正を正しく行うために、図２にに示す風壁面風圧の測定において、図３の信号発生器とスピーカーを用いて減衰と位相差を求めたのと同じ性能の圧力計、測定孔切り替え器を用い、さらに、同じ材質、同じ長さ、同じ太さのチューブを用いて行うことが望ましい。
【００２８】
【実施例】
実施例１
図３におけるチューブ２に外径２ｍｍ、内径１ｍｍ長さ７００ｍｍのビニールチューブを用い、圧力計５、５′には応答周波数が３８０Ｈｚのものを用い、さらに測定孔切り替え器４にはスキャニングバルブを用いた。
【００２９】
信号発生器９でホワイトノイズの信号を発生させ、該信号をスピーカ１０で音圧にし、圧力計５、５′で、共にサンプリング時間を１．３ｍｓｅｃとし、４０９６個のデータを同時に測定した。圧力計５、５′で測定した結果をそれぞれフーリエ変換し、パワースペクトルとクロススペクトルを求めて、圧力計５の測定における振幅と位相に対する補正値を求めた。
【００３０】
求めた補正値を用いて、圧力計５で測定された波形を補正したところ、図４に示す結果が得られ、圧力計５′で測定された波形とよく一致し、精度良く補正されていることが確認された。
【００３１】
比較例１
サンプリング時間を２ｍｓｅｃとした他は全て実施例１と同様にして、波形の振幅と位相を補正するための補正値を求めた。
【００３２】
圧力計５で測定した波形を補正した結果は図５のようになり、周期性はほぼ一致し、位相の補正は良かったが、振幅は全く一致せず、補正ができなかった。
【００３３】
【発明の効果】
本発明の風洞実験方法は、安価で正確な風圧測定を行うための実験手段を提供する。
【図面の簡単な説明】
【図１】模型に加わる風圧をビニールチューブで圧力計に導き測定する、風圧の測定方法を模式的に示す図。
【図２】模型に加わる風圧をビニールチューブで圧力切り替え器に導き、圧力切り替え器から圧力計に導かれた風圧を測定する、風圧の測定方法を模式的に示す図。
【図３】圧力切り替え器を用いる風圧測定の、補正値を求めるための測定を模式的に示す図。
【図４】実施例１で測定した圧力切り替え器を用いて測定した圧力変動の、補正前、補正後および、圧力計で直接測定した圧力変動を比較するグラフ。
【図５】比較例１で測定した圧力切り替え器を用いて測定した圧力変動の、補正前、補正後および、圧力計で直接測定した圧力変動を比較するグラフ。
【符号の説明】
１ 模型
２ チューブ
３ 測定孔
４ 測定孔切り替え器
５、５′ 圧力計
６ Ａ／Ｄコンバーター
７ パーソナルコンピュータ
８ 地面盤
９ 信号発生器
１０ スピーカー
１１ 遮音箱
１２、１２′ 測定孔
１３ 遮音板[0001]
TECHNICAL FIELD OF THE INVENTION
The wind pressure measuring method according to the present invention relates to a method for measuring a wind pressure generated in a wind pressure measuring hole provided in a building model in a wind tunnel experiment for estimating a wind load applied to a building.
[0002]
[Prior art]
The prediction of the wind load applied to a building is generally based on a wind tunnel experiment using a scale model of the building. The wind load applied to the building is divided into a load applied to the entire building and a wind pressure applied to the wall member. The load on the entire building is measured using a balance, and the wind pressure on the wall is measured using a pressure gauge. Patent Document 1 discloses a method for calculating a load applied to the entire building based on a wind pressure applied to a wall surface.
[0003]
The wind tunnel test of the wall wind pressure is performed to estimate the wind load applied to the wall surface of the building by the wind tunnel test. The wind load estimated by the wind tunnel experiment is mainly used for determining the design strength required for the members used for the building.
[0004]
As shown in FIG. 1, the wind tunnel test of the wall wind pressure is performed by using a scale model 1 of a building and providing a wind pressure measurement hole 3 for measuring a wind pressure on a wall surface of the scale model 1. The wind pressure generated in the wind pressure measurement hole is guided to the pressure gauge 5 through the flexible tube 2 made of plastic. The number of wind pressure measurement holes provided on the scale model is about several hundreds, depending on the size of the building and the scale of the wind tunnel experiment.
[0005]
The performance of the pressure gauge 5 has been improved, so that it is possible to measure a small pressure or a pressure fluctuating at a high frequency. Further, with the advent of a small and high-performance computer 7, a large amount of data processing can be performed.
[0006]
For this reason, in wind tunnel experiments, fluctuations in wind pressure can be measured accurately, and the measured wind pressure is analyzed separately for average wind pressure and fluctuation values, and the response of buildings and exterior materials to fluctuations in wind pressure is examined. It became so.
[0007]
In the wind tunnel experiment, in order to accurately measure the wind pressure applied to the wind pressure measurement hole 3, it is most preferable to provide the pressure gauge 5 directly in the wind pressure measurement hole 3. However, in most wind tunnel experiments, the interval between the wind pressure measurement holes 3 is narrow. It is difficult to directly install the pressure gauge 5 in the wind pressure measurement hole 5. Therefore, the wind pressure measurement hole 3 and the pressure gauge 5 are connected by the flexible tube 2, and the wind pressure applied to the wind pressure measurement hole 3 is transmitted to the pressure gauge 5 by the tube.
[0008]
Furthermore, connecting the pressure gauge 5 to all of the several hundred points of the wind pressure measurement holes 3 makes it difficult to calibrate the drift of the pressure gauge 5 in the measurement of a fluctuating wind pressure that requires a certain measurement time. Since the system becomes expensive, a measurement hole switch 4 is provided between the tube connecting the wind pressure measurement hole 3 and the pressure gauge 5 as shown in FIG. There is a method in which the pressure of many wind pressure measurement holes 3 can be measured by the pressure gauge of the above, and the wind pressure of many wind pressure measurement holes of several hundreds or more is measured by several to several tens of pressure gauges.
[0009]
In the wind pressure measurement performed by connecting such a wind pressure measurement hole and a pressure gauge with a tube and a measurement hole switch, the tube and the measurement hole switch attenuate the high-frequency component of the pressure fluctuation and reduce the phase shift (phase difference). Cause. Therefore, in order to correctly evaluate the fluctuation of the wind pressure, it is necessary to correct the attenuation and the phase difference.
[0010]
The correction values of the attenuation and the phase difference are obtained by the measurement shown in FIG. A white noise signal is generated by a signal generator 9, and the white noise signal is converted into pressure using a speaker 10 placed in a sound insulation box 11. The white noise signal has pressure fluctuations in a wide frequency range. The flat plate 13 provided with the pressure measurement holes 12 and 12 ′ is installed so as to partition the inside of the sound insulation box 11, and the pressure measurement hole 12 ′ is provided with a pressure gauge 5 ′ directly attached to the flat plate 13. The fluctuation is measured to obtain a measured value A. A tube used in a wind tunnel experiment and a measurement hole switch are connected to the pressure measurement hole 12, and the pressure fluctuation is measured by the pressure gauge 5 to obtain a measured value B.
[0011]
The measurement of the measurement value A and the measurement value B are performed simultaneously, and the measurement results are respectively subjected to Fourier transform to determine the magnitude and phase of the pressure at each frequency of the pressure fluctuation. The magnitude and phase of the pressure for each frequency are compared between the measured value A and the measured value B, and the ratio between the magnitudes of the pressure is attenuated, and the phase difference is defined as the phase difference.
[0012]
The attenuation and the phase delay are obtained in a range of 10 Hz to 200 Hz, which is known as a frequency range of the wind pressure fluctuation.
[0013]
Furthermore, the delay of the attenuation and the phase, the time series data of the pressure measured in the wind tunnel experiment, Fourier transform, find the magnitude of the pressure for each frequency, and perform correction using the aforementioned attenuation and phase difference, This is the result of wind pressure measurement in a wind tunnel experiment.
[0014]
In order to perform the correction correctly, the measurement of the wind wall pressure should be performed using a pressure gauge and a measurement hole switch with the same performance as the attenuation and phase difference obtained by using a signal generator and a speaker. This is done using tubes of the same length and length.
[0015]
[Patent Document 1]
JP-A-6-50839
[Problems to be solved by the invention]
When the wind pressure is measured using a measurement hole switch, the fluctuation pressure of 250 Hz or more has an attenuation of 85% or more, and the conventional correction has a large error and it is difficult to obtain a reliable measurement result. In addition, if a pressure gauge capable of responding even in a high frequency range of 1 kHz or more is used, stability is poor and measurement for a long time is difficult.
[0017]
[Means for Solving the Problems]
The wind pressure measuring method of the present invention is to install a building model provided with a wind pressure measuring hole in a wind tunnel, guide a wind pressure applied to the wind pressure measuring hole to a pressure gauge with a tube and a measuring hole switch, and determine a wind pressure applied to the building model. In the wind pressure measurement method to be measured, a pressure gauge having a maximum response frequency fp of 300 Hz to 500 Hz is used to generate a pressure fluctuation due to a white noise signal using a signal generator and a speaker. / (2 fp), measuring the amplitude and phase of the wind pressure generated by the tube and the measurement port switch, and using the corrected values to correct the wind pressure applied to the wind pressure measurement hole of the building model. This is a characteristic wind pressure measurement method.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
The length of the tube that connects the wind pressure measurement hole provided on the model used for measuring the wall wind pressure and the pressure switch has a variable component that attenuates depending on the length of the tube. It is desirable to use a tube of a fixed length.
[0019]
The longer the tube, the greater the pressure attenuation, so it is preferable to keep it as short as possible.However, if the length of the tube cannot be adjusted to a certain length due to the shape of the building model, a correction value for each tube length should be obtained. Good.
[0020]
In the wind tunnel experiment, since the fluctuation component is evaluated at 200 Hz or less, it is preferable that the maximum response frequency fp of the pressure gauge be 200 Hz or more. More preferably, the maximum response frequency fp is desirably 300 Hz or more in order to sufficiently secure the accuracy of the high frequency component.
[0021]
Further, if the maximum response frequency fp becomes high, it is difficult to perform stable measurement for a long time due to zero drift, so that fp is preferably 500 Hz or less.
[0022]
The correction values of the attenuation and the phase difference are obtained by using the device shown in FIG. A white noise signal is generated by a signal generator 9, and the white noise signal is converted into pressure using a speaker 10 placed in a sound insulation box 11. The white noise signal is preferably a signal in a frequency range up to 1000 Hz.
[0023]
The flat plate 13 provided with the pressure measurement holes 12 and 12 ′ is installed so as to partition the inside of the sound insulation box 11, and the pressure measurement hole 12 ′ is provided with a pressure gauge 5 ′ directly attached to the flat plate 13. The fluctuation is measured to obtain a measured value A. A tube used in a wind tunnel experiment and a measurement hole switch are connected to the pressure measurement hole 12, and the pressure fluctuation is measured by the pressure gauge 5 to obtain a measured value B. It is desirable that the time interval for measurement is set to 1 / (2 fp) of the maximum response frequency fp of the pressure gauge because high-frequency components around 200 Hz can be accurately corrected.
[0024]
The measurement of the measurement value A and the measurement value B are performed simultaneously, and the measurement results are respectively subjected to Fourier transform to determine the magnitude and phase of the pressure at each frequency of the pressure fluctuation. The magnitude and phase of the pressure for each frequency are compared between the measured value A and the measured value B, and the ratio between the magnitudes of the pressure is defined as a correction value for attenuation, and the deviation in phase is defined as a correction value for phase.
[0025]
The correction values for the attenuation and the phase are preferably obtained in a range of 10 Hz to 200 Hz, which is known as a frequency range of the wind pressure fluctuation.
[0026]
Further, in the correction of the attenuation and the phase, the time series data of the wind pressure measured in the wind tunnel experiment is subjected to the Fourier transform, the magnitude of the wind pressure for each frequency is obtained and corrected, and the wind pressure measurement result of the wind tunnel experiment is obtained.
[0027]
In order to correctly perform the correction, in the measurement of the wind wall pressure shown in FIG. 2, a pressure gauge and a measurement hole switch having the same performance as those obtained by determining the attenuation and the phase difference using the signal generator and the speaker of FIG. 3 are used. It is desirable to use a tube of the same material, the same length, and the same thickness.
[0028]
【Example】
Example 1
A vinyl tube having an outer diameter of 2 mm, an inner diameter of 1 mm and a length of 700 mm is used for the tube 2 in FIG. 3, a response frequency of 380 Hz is used for the pressure gauges 5 and 5 ′, and a scanning valve is used for the measurement hole switching device 4. Was.
[0029]
A signal of a white noise was generated by the signal generator 9, the signal was converted to a sound pressure by the speaker 10, and the pressure gauges 5 and 5 ′ were simultaneously measured with a sampling time of 1.3 msec and simultaneously measured 4096 data. The results measured by the pressure gauges 5 and 5 'were Fourier-transformed to obtain a power spectrum and a cross spectrum, and correction values for the amplitude and phase in the measurement by the pressure gauge 5 were determined.
[0030]
When the waveform measured by the pressure gauge 5 was corrected using the obtained correction value, the result shown in FIG. 4 was obtained. The result was well matched with the waveform measured by the pressure gauge 5 ', and was corrected with high accuracy. It was confirmed that.
[0031]
Comparative Example 1
A correction value for correcting the amplitude and phase of the waveform was obtained in the same manner as in Example 1 except that the sampling time was set to 2 msec.
[0032]
The result of correcting the waveform measured by the pressure gauge 5 is as shown in FIG. 5, and the periodicity was almost the same, and the phase correction was good, but the amplitude did not match at all and could not be corrected.
[0033]
【The invention's effect】
The wind tunnel experiment method of the present invention provides an experimental means for performing accurate and inexpensive wind pressure measurement.
[Brief description of the drawings]
FIG. 1 is a view schematically showing a method for measuring wind pressure, in which wind pressure applied to a model is guided to a pressure gauge with a vinyl tube and measured.
FIG. 2 is a diagram schematically showing a method of measuring wind pressure, in which wind pressure applied to a model is guided to a pressure switch by a vinyl tube, and the wind pressure guided from the pressure switch to a pressure gauge is measured.
FIG. 3 is a diagram schematically showing measurement for obtaining a correction value in wind pressure measurement using a pressure switch.
FIG. 4 is a graph comparing pressure fluctuations measured using a pressure switch measured in Example 1 before and after correction and pressure fluctuations directly measured by a pressure gauge.
FIG. 5 is a graph comparing pressure fluctuations measured using a pressure switch measured in Comparative Example 1 before and after correction and pressure fluctuations directly measured by a pressure gauge.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Model 2 Tube 3 Measurement hole 4 Measurement hole switch 5, 5 'Pressure gauge 6 A / D converter 7 Personal computer 8 Ground 9 Signal generator 10 Speaker 11 Sound insulation box 12, 12' Measurement hole 13 Sound insulation plate
