Abstract/Summary

Indoor velocity measurement techniques are categorized into point-wise and global-wise measurement techniques. Currently, measurements are either intrusive or restricted to the measurement area. This study presents a thermal image velocimetry (TIV)-based flow measurement method that is suitable for visualizing indoor two-dimensional velocity fields near indoor heated surfaces. The proposed technique uses only an infrared camera for mapping the surface temperature fluctuations. Image processing steps that are used to recover the velocity distribution include the decomposition of the video files into individual frames, the application of filtering to remove background noise, cross-calculation to estimate the velocity, and a final velocity correction based on the continuity equation. To investigate the feasibility of this method, natural convection was studied close to a heated vertical surface in a rectangular cavity. Thermal image velocimetry and particle image velocimetry (PIV) were used to visualize the flow field above a heating unit. The results indicate that the airflow field can be visualized by TIV, and the results measured by TIV are shown to be similar to those for the surface of 6 mm away from the heated surface measured by PIV. A linear correlation is established between TIV and PIV.