Simulysis Blog

Engineering challenge:

For control of pollutants and particulate flow into the atmosphere require continuous monitoring of gases in discharge chimneys. Among other requirements, the gas velocity must be measured in a plane at a specified distance from the discharge outlet. The flow in this plane must be as uniform as possible and the stream lines must be vertical, or inclined by no more than a few degrees. A common problem is the occurrence of cyclonic flow. The strong rotational velocity component makes the streamlines helical, invalidating conventional speed measurements with pitot tubes or other methods which can be sensitive to sensor misalignment with the flow.

A flow straightener, sometimes called a honeycomb, is a device used to straighten the air flow in a wind tunnel. It is a passage of ducts, laid along the axis of main air stream to minimize the lateral velocity components caused by swirling motion in the air flow during entry. The cross-section shapes of these "honeycombs" may be of square, circular and regular hexagonal cells.

The objective is to study the flow within and outside a chimney of low length/diameter ratio with a lateral inlet for combustion gases. The computational domain included the inlet chamber, the chimney and the atmosphere. The wide external domain allows more realistic results than those obtained by simply imposing a pressure condition at the chimney outlet, and it also allows to analyze the influence of wind in the chimney operation and the plume dispersion. The required fluid domain was modeled and meshed (Pre-Processing). The mesh file is then imported to a solver and different material property required for solving has to be specified. The necessary boundary conditions should also be given. The solving is then carried out and different results are then viewed in a Post-Processor. 
Result:
Velocity Contour:


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