Determination of the integral characteristics of an asymmetrical thermal plume from air speed/velocity and temperature measurements

Abstract

A method, named the Approximate Distributions Integration Method (ADI-method), is proposed for calculation of parameters of the asymmetrical thermal plume above a heat source, such as maximum air temperature excess and velocity, their position in the plume cross-section, the widths of the temperature and velocity profiles, asymmetry parameters of the plume cross-section, and the integral characteristics. The method is based on an approximation of the measured profiles of air velocity and air temperature excess in the plume cross-section. A procedure for conversion of the air speed measured by omnidirectional sensors into air velocity is incorporated with the ADI-method. Experiments were performed in a climate chamber with air temperature of 23 °C, radiant temperature equal to the air temperature and upward airflow with velocity of less than 0.05 m/s. Air speed and temperature in a thermal plume, generated by a thermal manikin resembling the complex body shape and heat generated by a sitting person, were measured. Using the measured data, the integral characteristics of the generated asymmetrical thermal plume were calculated by the ADI-method, and the uncertainty in determination of the characteristics was identified. At a height of 0.7 m above the manikin head, the mean integral characteristics of the plume and their 95% certainty range (in parentheses) were: volume flux 258 m 3/h (1.8%), momentum flux 0.0087 N (2.0%), buoyancy force density 0.0038 kg/s 2 (3.8%) and enthalpy flux 16 W (2.8%).