ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Operation of Functional Fluid by Local Wall Heating in a Drag-Reducing Surfactant Solution Flow
Sinopsis
In this study, we experimentally investigated the behaviors of wall friction and heat transfer coefficients in drag-reducing turbulent flow depending on the temperature of the solution, with change of the wall heat flux. Measurements were performed under conditions of wall heat flux ranging from 2.3 to 9.0 kW/m2, different concentrations of 25 and 40 ppm, and solution temperatures of 298.2 and 308.2 K. We used a PIV system to measure the instantaneous velocity in the x-y plane downstream from the point of onset of heating and at Reynolds numbers of 1.4×104 and 2.4×104. We found that, by increasing wall temperature, the mixing of fluid became active and the velocity gradient of the shear layer developed the same appearance as for water flow, in drag-reducing turbulent flow. Hence, the coefficients of heat transfer and wall friction of the drag-reducing flow were much lower than those of water flow at the same Reynolds numbers. Moreover, we found the dependence of drag reduction on the reciprocal of Karman constant and examined the concept of the micelle-association-length.