Distinctive features of the heat propagation from a localized source under the high-frequency vibration conditions

The results of studying the propagation time of thermal disturbance in a cylindrical fluid layer caused by a localized heating from below are obtained. The temperature of the fluid near the upper isothermal boundary is measured. By recording the temperature above the heater, the heat propagation time is measured from the moment the heater is turned on till the temperature sensor comes into action both in the static case and under conditions of high-frequency longitudinal and transverse vibrations (the frequency is equal to 6 Hz, the amplitude is equal to 4 mm). For the same conditions, a comparison of the temperature drop inside the column of heated fluid at a steady-state flow is carried out. The assessment of heat loss inside the heated fluid column is performed on the basis of temperature measurements for a steady-state jet. Although the paper emphasized the need to take into account the delay associated with the finite time of heat transfer from the heat source to the fluid, it was not possible to comprehend the development of the flow immediately after the heating was turned on due to the absence of visualizing particles or dye in the fluid.