Observations relating to the efficiency of mixing in rapid reaction flow devices.

The principle of dimensional analysis of liquid flow has been applied to the problem of rapid mixing in flow apparatus. A model of the Hartridge-Roughton mixing chamber and observation tube has been scaled approximately 1/1.000 so that the times after mixing are approximately 6 s, the flow velocities are the order of 2 cm/s, and the distance from mixing to observation is 120 mm. Visual observation is employed to observe the end point of the mixing of acid-base with a color indicator, thymol blue. Quantitative estimates of the effect of the number of jets, the effect of screens placed in the flow stream, and the angle of jets, one with respect to another, lead to quantitative evaluations of these parameters for the scale model. The extent to which these parameters apply to the full-scale apparatus at faster flow velocities suggest that the general principles employed in the scale model are valid, although more emphasis is placed upon turbulence generation at the low flow velocities employed in this experiment than at the faster flow velocities employed in the full-scale apparatus.