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 bT 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 [22], defines the limit of the two zones around Grz = 2.7 × 10exp7 and places the beginning of transition at Grz = 4.7 X 10exp7, following a law Grz exp −1.14. The flow does not reach a fully developed turbulent regime.