Identifier

etd-11162005-152703

Degree

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Document Type

Thesis

Abstract

The goal of the present study is to investigate the relationship between incident wind velocity fluctuations and the surface pressure fluctuations on the roof of a low rise building. The goal was fulfilled by studying the pressure velocity correlation on 1:50 scale model of a typical low rise building, the Wind Engineering Research Field Laboratory (WERFL) building located at Texas Tech University, Lubbock. The experimental study was carried out in the LSU Wind Tunnel Laboratory by simulating the boundary layer prevalent at the full-scale site. The velocity profile in the boundary layer was measured using the TSI Hot-Wire system with an in house designed data acquisition system controlled by Labview. Due to the short length of the development section of the wind tunnel, artificial devices (spires and a castellated trip) were used to help achieve the required boundary layer depth at the center of the test section. The longitudinal mean velocity profiles matched the full scale results up to six and a half building heights following a power law profile with an á value of 6.3. The Jensen number matched with full-scale value of 285 with the modeled surface roughness length of 0.27 mm. Validation of the boundary layer simulation was carried out by measuring the point pressure coefficients (Cpmean, Cppeak and Cprms) on the surface of the model as a function of wind azimuth. This data was compared to model scale (1:50) study carried out at Colorado State University and the full-scale data. Mean point pressure coefficients were in close agreement with published wind tunnel and full-scale results. Fluctuating pressure coefficients (peak positive, peak negative, rms) exhibited a great deal of scatter. The pressure-velocity correlation experiments were carried using the data acquisition system designed to simultaneously acquire the velocity and pressure signal. The cross-correlation results between the incident wind and point pressure region on the model experiencing extreme pressure in the roof region matched qualitatively with full-scale results. The maximum pressure-velocity correlation, mean, peak negative and rms pressure coefficients contour plots on the roof region for flow perpendicular to long and short wall followed the qualitative trend.

Date

2005

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Dimitris E. Nikitopoulos

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