A STUDY ON HEAT TRANSPORT PHENOMENA IN A DEVELOPED THERMAL BOUNDARY LAYER OF DRAG REDUCING CHANNEL FLOW

摘要

The heat transport phenomena in a developed thermal boundary layer of surfactant solution flow were investigated experimentally. The experiment was conducted under different surfactant additive concentrations. The temperature fluctuations in a thermal boundary layer in a smooth channel flow were measured by fine-wire thermocouple probe. Heat transfer reducing rate and temperature fluctuation characteristics including mean temperature distribution, intensity, wave form, spectral density function, and skewness factor were studied. The results showed that the turbulent transport is obstructed by additives, and the temperature field shows dramatic changes. High frequency component of temperature fluctuation of surfactant solution flow was decreased due to suppression of turbulence and viscoelasticity. Large temperature fluctuations occur in the thermal boundary layer because the development of the thermal boundary layer is obstructed, and large temperature fluctuations appear to concentrate the temperature gradient in the near-wall region (10