Studies on mechanism of outbreak and disappear of drag reduction by temperature change

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17560180
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Gifu University
• Principal Investigator: KUMADA Masaya Gifu University, Environmental and Renewable Energy Systems division, Professor, 大学院工学研究科, 教授 (30021603)
• Co-Investigator(Kenkyū-buntansha): IKEDA Masahiro Gifu University, Environmental and Renewable Energy Systems division, Assistant, 大学院工学研究科, 助手 (10397317)
• Project Period (FY): 2005 – 2006
• Keywords: Drag Reduction / Non-isothermal heating / Cationic Surfactant / cetyltrimethyl ammonium chloride / sodium salicylate / Temperature profile

Research Abstract

The purpose is to find the practicable control method of the outbreak and disappear of drag reduction by the addition of small amount of surfactant.
Control of the reduction in turbulent friction drag of water flow by the addition of small amount of surfactant has been done by three parameter, 1. the concentration of additional surfactant, 2. temperature of the solution, and 3. velocity of the solution. In practical applications to heat exchanger, however, it is difficult to change the concentration of surfactant and velocity of the solution in operation. Change of temperature of duct wall by heating and cooling locally has the only possibility.
The outbreak and disappear of drag reduction phenomenon are observed on the condition that temperature of the solution near the wall go over or go down the critical value. These critical values depend on the concentration of additional surfactant and velocity of the solution. Furthermore, the place of critical temperature is about 0.1mm from the wall and within this range, temperature is almost constant.
The extent of temperature from the outbreak to the disappear of drag reduction phenomenon depend on the concentration of additional surfactant, temperature of the solution, and shear velocity of the solution. The change process from the outbreak to disappear of drag reduction phenomenon due to temperature is not sharp and the hysteresis was observed.
Specially, in the case of concentration of additional surfactant over about 1000ppm, change of viscosity depend on temperature. In this case, reduce of drag and change of Reynolds number occur at the same time. But, we need an in-depth survey and data.
Possibility of control of the reduction in turbulent friction drag of water flow by the addition of small amount of surfactant made clear in this experiment using a closed loop flow channel and the cationic surfactant used was cetyltrimethyl ammonium chloride(CTAC),which was added with the same weight of sodium salicylate as the counter ion.