Pipe design for improved particle distribution and improved wear
This thesis describes the use of swirl-inducing pipes in water and water/mixture flows, with a particular emphasis on production of swirl before a bend. The author takes ideas for imparting swirling action to particle laden liquids which have occurred in one form or another throughout the 20th Century. The aim of the project was to reduce wear and produce better particle distribution throughout a bend. In the present investigation two methods were used in the examination of swirl-inducing pipes, namely experimental and numerical. The experimental method made use of a Swirly-flo pipe, which is normally found in marine boilers and is used to improve heat exchanger efficiency. The Swirly-flo was then placed onto an experimental test rig, which was specifically designed to provide insight into the use of swirl-inducing pipes. The numerical method came from a commercial Computational Fluid Dynamics (C.F.D.) package which allowed the author to examine various shapes for pipes and provided information on the flow fields in a swirl-inducing pipe. From the experimental results it was shown that swirling the flow before a bend produced less pressure drop across the bend than non-swirling flow. However, the Swirly-flo pipe produced a greater pressure loss across its length than the standard pipe. By swirling the particles before the bend the particles were more evenly distributed throughout the bend, which has the potential to remove the characteristic wear zones. Computational Fluid Dynamics was used to investigate various Swirly-flo designs. These studies indicated that the optimum pitch to diameter ratio was shown to be 8 for a constant pitch Swirly-flo pipe, which was consistent with previous work.