MEASUREMENTS OF THE TEMPERATURE FIELD IN AN AXISYMMETRIC THERMAL PURE PLUME

Abstract

An experimental study of the temperature field of a thermal pure plume rising from a heated disk immersed in an air-filled enclosure is presented. The measurements were carried out with a fine thermocouple. The centerline temperature distribution verifies the law —5/3 corresponding to a zone of self-similarity. The profiles of temperature, which follow Gaussian behavior, allow one to define two zones. The half-width of temperature b_T and the spread rate are determined and compared with those of other authors. The centerline temperature distribution, according to the dimensionless form proposed by Bill and Gebhart [122], defines the limit of the two zones around Gr_z = 2.7 × 10⁷ and places the beginning of transition at Gr_z = 4.7 X 10⁷, following a law Gr_z ^−1.14. The flow does not reach a fully developed turbulent regime.