Use of CFD Analysis in Designing a Channel Mixing Structure

摘要

Design of wastewater treatment facilities often entails mixing of various flow streams and chemicals. Adequate mixing can be a critical component of the overall treatment plant performance. The required mixing can be accomplished with mechanical mixers but mechanical mixers can be expensive to install and operate. An alternative to mechanical mixers is to install structural features that create turbulence and promote the mixing of flow streams and chemicals. However, it can be very difficult to evaluate the effectiveness of this type of passive mixing to achieve the desired goal. In addition, these structural features will create headloss which may increase the plant power requirements. Therefore, it is important to evaluate the complex hydraulics around these structural features to develop a cost effective design.This paper presents a case study to illustrate how CFD analysis can be used to assist with the evaluation and design of channel mixing features. It will illustrate the flow characteristics of several mixing structures and compare their mixing and headloss characteristics. It will demonstrate how the insights gained from CFD analysis can be useful in the practical design of a wastewater treatment plant mixing channel.