Injection of Drag Reducing Additives into Turbulent Water Flows. Techniques for Concentration Measurements and Reynolds Number Scaling.

The basic goals of this project are to determine the mechanisms by which drag-reducing additives modify the turbulent transport near walls and to develop optimum methods for injecting these additives into flows of water. The purpose is to develop methods for controlling and manipulating turbulent wall flows. This report describes a technique for deducing both time-average and instantaneous values of local additive concentration. The technique is based on measurement of the fluoresced radiation from dye-marked additive. The flow-rate capacity of the flow loop has been increased by the addition of two pumps. One-component laser velocimeter measurements are presented that verify the standard character of the flow in the 2.5 x 25 cm, two dimensional channel at a Reynolds number of 49,300. This increase in Reynolds number capability will be used to verify scaling relationships for the time between wall-layer bursts for flows with and without additives. Author