THE USE OF SURFACE HOT-FILM SENSORS IN DILUTE POLYMER FLOWS
GOFORTH, MONTGOMERY BAILEY
Master of Science
The purpose of this study was to assess the feasibility of using flush-mounted surface hot-film sensors in dilute polymer solutions to measure mean wall shear stress. Experiments were conducted using hot-film sensors mounted on the surface of a rotating disk. It is shown that a sensor calibration obtained in a pure water flow cannot be used directly to provide accurate skin friction measurements in a dilute polymer flow. However, the repeatability of the results suggests that a functional relation may exist between a sensor's calibration in water and in dilute polymer, thereby permitting precalibration of the sensor in pure water. It is also possible that reasonably consistent measurements may be obtained by precalibration of sensors in controlled polymer solutions. Experiments were also conducted by injecting concentrated polymer solution (4000 ppm) into the boundary layer of the rotating disk. Drag reduction and hot-film performance comparable to that obtained with homogeneous dilute polymer solution was demonstrated.