Study On Turbulence Integral Scale Of Landfalling Typhoon Based On Field Measurements

In the modern engineering structural design, owing to sensitivity of thestructure to the turbulence integral scale, the turbulence integral scale in theproject has become an important indicator to the measured wind characteristics.There are a large difference between typhoon and normal wind. Publishedresearch results on the turbulence integral scale mostly refer to normal wind orthe strong wind in the outer area away from typhoon. The strong wind area inthe typhoon eye wall has more complicated turbulence characteristics and moredestructive than the normal wind. As a result the turbulence integral scale of thestrong wind area in front of the typhoon eye wall become the focus of thisarticle. The existing methods to calculate the turbulence integral scale have alot, but owing to differences in assumptions, the turbulenc e integral scale incalculation are quite different. This article will select the appropriatecalculating method of the turbulence integral scale, and do a analysis of theturbulence integral scale of the strong wind area in front of the typhoon eyewall on the basis of exploring the turbulence integral scale of the fluctuatingwind. The main content of this paper is as follows:(1) Through selecting and pretreating the measured sample data of thenormal wind, we compared the10min’s average wind characteristics betweentwo groups of data referring to normal wind. Then as for the Karman spectrumfitting, the spectrum should be fitted with the measured fluctuating wind speedspectrum and the mean variance method was used to carry out error analysis. Atlast, on the basis of their own assumptions and other restrictions, this articlegiven a comparison between the direct integration method mentioned in thisarticle of the autocorrelation function and Karman spectrum fitting method tocalculate turbulence integral scale and analyze their stability.(2) We analysed the average wind characteristics for the strongtyphoon-Hagupit. According to the different position of typhoon wind, typhoonis divided into the strong wind area in front of typhoon eye wall, the strongwind area behind typhoon eye wall and the outer area away from typhoon. Wecalculated the turbulence integral scale in the strong typhoon Hagupit’s differentpositions by using the direct integration method of the autocorrelation functionand Karman spectrum fitting method, and besides, we make a comparationbetween two methods in computing the turbulence integral scale. We discussedthe relationship between the average wind speed and turbulence integral scale,the relationship between atmospheric stability and turbulence integral scale. At last, in this paper, the turbulence integral scale of typhoon-Hagupit wascontrasted with other Typhoon processes, as well as the exratropical cyclone.