Flow Properties of Surfactant Aqueous Solutions in Pipe Junction

This article describes the flow properties of surfactant aqueous solutions in a pipe junction with branching angle of 90 degree. The effects of concentrations and temperatures on junction loss coefficients were investigated. The surfactant used is Ethoquad O/12 (C18H35N(C2H4OH)2CH3Cl). The surfactant and equimolar amounts of NaSal (HOC6H4COONa) were dissolved in tap water. The concentrations of surfactant aqueous solution were ranged from 100 to 1000 ppm. The experiments were carried out at 15, 20, 30 and 50°C. Pressure losses due to branching and wall pressure distributions were measured. Pipe friction losses before and behind the junction were also measured. The pipe friction factors before and behind the branch differed from each other. The critical Reynolds number, at which drag reduction is lost and the friction factor agrees with the Blasius's equation, decreased with increasing concentration of surfactant and increasing temperature. Those solutions showed overshooting phenomenon that the recovery pressures of main flow became higher than the pressure at a starting point, which was not observed in tap water. Dividing loss coefficients were higher than those for Newtonian fluid below the critical Reynolds number and were identical with each other above it. The dividing loss coefficients increased with increasing concentration of the surfactant as well as with decreasing temperature.