Conference Presentations by Chelakara Subramanian
American Assoication of Wind Engineering, 2018
This work deals with statistical analysis of LIDAR or Laser based Radar system wind speed data, m... more This work deals with statistical analysis of LIDAR or Laser based Radar system wind speed data, measured at 10 different user defined heights. Wind profiles of near surface with different roughness values are analyzed. The two commonly cited classical approaches; power law (with an exponent of 1/7) and logarithmic law (with a reference roughness length of 0.01m) are used to extrapolate the upper level wind speed to the surface by knowing speed at a reference height (usually 10 m, the standardized anemometer height). In this research, a deviation from this expected "log law" or "power law" velocity profiles is observed for different surface conditions. So here, a universal non-dimensional velocity vs height profile is developed to account for a specific "Equivalent Surface Roughness Factor" which incorporates appropriate momentum and energy losses due to vortex formation and decay for different roughness values The experimental data sets contained wind direction, horizontal and vertical velocity component values. Velocity profiles for various region were plotted and the consequent free stream velocity and roughness factor were calculated using probabilistic approach. Log Normal curve seems to fit the distribution of roughness factor for various regions. Turbulence intensity data was analyzed to determine multiple spatial and temporal scales. All these results can be used to precisely model wind fields for wind turbine design, design of buildings and bridges etc.
American Association of Wind Engineering, 2018
This work presents the results of wind pressure and velocity fields measured on the roof of a Sat... more This work presents the results of wind pressure and velocity fields measured on the roof of a Satellite Beach, Florida residence (longitude and latitude: 28.175944,-80.592710) using the Florida Tech's Wireless Sensor Network system (WSN), during the passage of Hurricane IRMA (2017). The data was collected at a sampling rate of 10 samples per second and was continuously collected for 36 hours starting at 11:56 am on 8 September 2017. The stationarity of the flow field during the Hurricane period is studied using the variable interval time averaging (VITA) technique. The pressure data showed Gaussian behavior, however, a deviation was observed during period of maximum pressure dip. Pressure gradient effects on the boundary layer at roof edges were observed using pressure changes. Spectral analysis was performed to find the key periodicity in data. The value of Turbulence intensity (T.I.) was found to go as high as 0.5-0.8 which reflects presence of starkly varying energy exchange mechanisms. Wind velocity data was plotted to show the local mean speed variations on rooftop. Cross correlation analysis was used to describe pressure and velocity relationship.
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Conference Presentations by Chelakara Subramanian