Assessment Of A Confined Thermal Plume By Piv Combined With Pod Analysis

A comprehensive understanding of the flow characteristics of thermal plumes during cooking is an essential prerequisite for designing high-performance cooker hoods. A cooking-related thermal plume under the confinement effect of a wall-mounted range hood in a real-sized kitchen is investigated utilizing particle image velocimetry. The experiment was conducted at Froude numbers ranging from 0.26 to 0.41 with different mounting heights (600 and 750 mm) and heating temperatures (100 and 260 degrees C). The plume behavior in the confined environment is described in the first section. The velocity profiles followed Gaussian functions well except at the impingement zone. In comparison with a thermal plume in a large space, the growth and decay rates of the velocity along the centerline were enhanced under a confined environment. The normalized velocity and temperature profiles along the centerline presented a clear confined height dependency and heating-temperature dependency. The turbulent intensity was relatively high in the zone near the heat source ((h(0)/h) z/D < 0.6) and impingement zone ((h(0)/h)z/D > 2.7). In addition, the distribution of skewness and kurtosis of the velocity fluctuations showed a Gaussian distributions in the zone of 0.4 < (h(0)/h)z/D < 2.7. Then, vortex and turbulence structures were examined utilizing vortex identification method and proper orthogonal decomposition (POD). The POD analysis visualization showed that the fluctuating energy for the development of plumes was dominated by the vertical velocity fluctuation. Finally, it was found that airflow rate profile of thermal plume follows a logarithmic function with height in the entrainment zone ((h(0)/h)z/D < 2.7).