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With devices involving the combustion of gas – whether that is a gas turbine combustor, a furnace burner, an industrial process heater or boiler, a burner of a stovetop appliance, or a gas-fired water heater – if your primary objective is to use simulation to “discover better designs, faster” – then I’d say that yes, CFD performed with STAR-CCM+ can be trusted to help you achieve that goal.  

“OK, then how?” you might ask. Well, let’s start with a light-hearted exercise… Quickly, which one of the two target-shooting performances shown below is better?  

Again, I would say the answer depends on your ultimate objective and requirements. On one hand, if your objective is shorter-term (i.e., only to get the highest score once), then the performance on the left is better.  On the other hand, if you are thinking longer-term and plan to repeatedly shoot additional sets of five shots, then I would say that the performance on the right is likely better. Why? Because it will be MUCH easier to make a simple adjustment to the gun-sighting and thereby move all five tightly clustered shots up-and-to-the-left (closer to the bullseye) for a much better score.  

STAR-CCM+ for combustionIn order to achieve more repeatable and better results with CFD, using that same type of methodical thinking is valuable. In fact, with any type of engineering simulation, I relentlessly advocate for use of a Crawl-Walk-Run approach. Why? Well, throughout my 25-plus years in the engineering simulation world, I have seen this type of methodical approach yield positive rewards. By contrast, the opposite approach (i.e., trying to run before crawling or walking), often leads to frustrating and unproductive simulations that are the figurative equivalent of painfully falling down and scraping hands and knees, getting up, sprinting, falling again, etc.  

So this blog post is intended for those of you who are willing to crawl and walk with your use of CFD to predict the performance of devices involving gas combustion. For those of you who want to run (for example, by performing LES simulations of a full 360-degree gas turbine combustor to study combustor acoustics), I’m sorry, but that will need to wait for another discussion, another day… not because it can’t be done today, but because I want to start with first things, first – with what I would call “low-hanging fruit.” To design better performing gas combustion devices, you can derive tremendous value, today, by using CFD with STAR-CCM+ to derive numerous performance-related insights.

For instance, as many other engineers routinely use STAR-CCM+ to do, you could identify better gas-combustor designs by:

  • Visualizing air flow patterns, especially of the cooling air – and then changing the geometric design to re-route cooling air so as to make the most effective and efficient use of it.

  • Fine-tuning fuel/air mixing to obtain a desired equivalence ratio; to enhance combustion completeness; to minimize wasteful, unburned fuel; and to minimize harmful emissions of NOx and CO.

  • Understanding fuel flexibility – by predicting the performance of the same combustor when operated with different fuels, and readily making A-to-B comparisons.

  • Avoiding hot spots on liner walls, minimizing thermal stress, and improving reliability and lifting by predicting temperatures and temperature uniformity – especially by leveraging Conjugate Heat Transfer (CHT) in STAR-CCM+ to accurately predict temperature gradients throughout solid components.  

  • Understanding flame characteristics (such as location and shape) – to know where flames may impinge on metal components, for instance.  

Now, when you are ready to Run with your gas combustion simulations with STAR-CCM+, such as with LES simulations of a full 360-degree gas turbine combustor, be sure to let us know. ☺

On that note, I encourage you to read the blog of my colleague, Karin Frojd, which is heavily focused on Reacting Flows – in particular, her recent post on related enhancements to STAR-CCM+ v12.02, such as Adaptive Combustion Table Discretization.

 

 

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