Statistical Analysis of Wind Tunnel and Atmospheric Boundary Layer Turbulent Flows

Abstract

Adrián Rober"o Wi""wer, G"ilherme Sa"sen Wel"er and Acir M. Loredo-So"za Addi"ional informa"ion is available a" "he end of "he chap"er h""p://dx.doi.org/10.5772/54088 . IntroductionMany studies on wind engineering require the use of different types of statistical analysis associated to the phenomenology of boundary layer flows. Reduced Scale Models RSM obtained in laboratory, for example, attempt to reproduce real atmosphere phenomena like wind loads on buildings and bridges and the transportation of gases and airborne particulates by the mean flow and turbulent mixing. Therefore, the quality of the RSM depends on the proper selection of statistical parameters and in the similarity between the laboratory generated flow and the atmospheric flow.The turbulence spectrum is the main physical parameter used to compare the velocity fluctuation characteristics of atmospheric and laboratory flows in Wind Load Modeling WLM . This is accomplished by fitting experimental spectra to some functional form, e.g., von Kár-mán, Harris or "atchelor-Kaimal formula, and then creating dimensionless turbulence spectra in accordance with a similarity theory [ , , ]. The objective behind the use of a similarity theory is that the dimensionless spectra of atmospheric and laboratory flows collapse, if the dimensionless spectra were constructed by appropriate parameters [ ].This classical spectral comparison is commonly used in WLM [ ]. However, some difficulties, related to the determination of the inertial range extent, choice of characteristic velocity and length scale parameters and possible effects due to the finiteness of the Reynolds number arise in wind tunnel studies, specially, when simulations are performed at low velocities [ ].Considering this scenario, a complementary study taking into account the use of local scale based Reynolds number, inertial and dissipation range characteristic scales, control of sampling frequency and post-processing filtering is proposed. Selected data sets obtained under © 2013 Wi""wer e" al.; licensee InTech. This is an open access ar"icle dis"rib""ed "nder "he "erms of "he Crea"ive Commons A""rib""ion License (h""p://crea"ivecommons.org/licenses/by/3.0), which permi"s "nres"ric"ed "se, dis"rib""ion, and reprod"c"ion in any medi"m, provided "he original work is properly ci"ed.

Experimental Investigation of a Prandtl Probe Fabricated Using Desktop Stereolithography Technology

“…This presents a challenge whereby institutions opt either to design or buy new wind tunnels with bigger test sections or carry out their experiments at the exit end of these open jet subsonic wind tunnels. The latter being a cheaper option, a need to explore the quality of the exit flow such as the mean flow and velocity profile arises [8]. This is done using specialized wind speed measuring instruments such as the Prandtl probe.…”

“…This presents a challenge whereby institutions opt either to design/buy new wind tunnels with bigger test sections or carry out their experiments at the exit end of these open jet subsonic wind tunnels. For the newly designed wind tunnels (being a cheaper option) and the option of carrying out experiments at the exit end of the existing open circuit wind tunnels, there is need to perform a number of flow characterization in order to explore the quality of the flow such as the mean flow, velocity profile, and turbulence /spectral intensity [8].…”

Characterization of a new open jet wind tunnel to optimize and test vertical axis wind turbines

“…A number of analyses deal with exploring the quality of the flow (mean flow, velocity profile, and turbulence/spectral representation). [10][11][12] An important incitement is made by the wind power industry, supporting actions in investigating the appropriateness of wind tunnels for calibration of cup anemometers, as defined, for example, by the Measuring Network of Wind Energy Institutes (MEASNET) and wind turbine power performance measurement standards (see, for example, the standard IEC61400-12-1/2005 by the International Electrotechnical Commission). The cup anemometer is presently the accepted wind sensor to be used in wind turbine power performance accredited measurements.…”