Abstract
This objective of this thesis is to investigate the aphics. mixing offered by turbulent jets. This study focuses on the specific application of low viscosity jets (1-30 cP) introduced for the purpose of mixing non-stratifying, miscible fluids in vertical cylindrical vessels. The primary goals of the testing were: to determine the primary variables affecting mixing time in jet-mixed vessels; to develop correlations for mixing time based upon these variables for single and multiple jet systems, and; to compare the mixing induced by jet mixers to that produced by traditional mechanical agitation systems. The results are thus meant to serve as a basis for comparison of alternative mixers in the scoping and design of process agitation. Testing was performed in two cylindrical, acrylic vessels (17.5'5 and 45.5'5 diameter) using various mixer designs including: single side-entering jet mixers; multiple side-entering jet mixers; pipe and ring sparkers; radial- and axial-flow impellers. This research, for the most part, confirms many of the findings of previous studies of jet mixing. First, mixing time in jet-mixed systems depends primarily upon the mass of the fluid in a tank and the amount of addition, to maximize the efficient transfer of momentum, the distance that the jet can travel prior to impingement on a wall should be maximized. This impingement at the wall may hamper mixing if significant velocities still exist at impingement. Lastly, kinematic viscosity has a significant effect on mixing time. Unfortunately, due to limited testing on the effects of viscosity, this correlation is tenuous. Comparison of different mixers revealed that impeller systems remain significantly more efficient than their jet counterparts on the basis of energy input to the tank fluid required to achieve a given mixing time. Despite attempts to design efficient multiple jet systems, the reduction of jet path in these systems reduced their efficient use of momentum. As result, single jet systems with equivalent momentum rates achieved a degree of mixing more rapidly than any of their multiple jet counterparts.
Schulte, Casey M (1998). Characterization of turbulent jet mixing in cylindrical tanks. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1998 -THESIS -S364.