Introduction

This case study presents the use of Azore® as an engineering design evaluation tool. The system being analyzed is a merging duct system where a hot gas stream is introduced through multiple feed ducts into a cold gas stream in a larger primary duct. The typical question for this situation is, what will be the temperature distribution downstream of the hot/cold merge point? Most likely the temperature distribution will be fairly stratified, and depending on the application may be unacceptably stratified. If there are temperature stratification requirements, then a flow mixing device must be designed to achieve the proper mixing.

Case Setup

Azore is a suitable tool for evaluating mixer designs for this situation. For discussion purposes two mixing scenarios have been simulated. The first scenario characterizes the temperature distribution in the duct system when no mixing device is used. The second simulation evaluates a potential mixer design.

Results

There are many different design criteria that can be used to evaluate temperature mixing:

  • the relative gas minimum/maximum temperature
  • the variation from the mean temperature
  • the percent of the cross section that falls within different temperature bands.

Any one of these methods has merit and can be used as a way for evaluating and comparing different temperature mixer designs. In the image below, the gas temperature is shown at a number of planes down stream of the merge point. Notice that when the temperature mixer is introduced, the hot gases are distributed much more evenly across the primary gas stream rather than remaining along one side of the duct.

 

Mixer temperature comparison