It's a bird! It's a plane!

Brent Cullimore

This is a story of how one bird drains while another bird drinks.

The bird that drains is a commercial airliner.

The bird that drinks is a toy. Though I really wish it had been this chirpy chap:


(photo source)

The bird that drains came first. Satisfying safety regulations requires the prediction of fuel and ullage temperatures in commercial aircraft. Not just steady states. Not just a transient or two. Tens of thousands of transient flight scenarios must be simulated.

This type of simulation is way beyond the reach of 3D CFD, and it requires a lot more than flow network solvers could do, even with the ability to link to detailed thermal geometry like FloCAD. Here at CRTech, we also were facing many other requirements for detailed but fast-solving applications such as liquefied natural gas (LNG) tanks, MRI magnet-cooling helium dewars, boilers and steam drums, immersion-cooled electronics, and so forth. It seemed like “partially filled and complexly shaped vessels” were everywhere, and no one was addressing their special needs.

So with a little help from our customers, we spent a few years developing Compartments and their associated fluid Ports.

How do we explain what a “partially filled vessel” even means, or why this so different from either CFD or a piping code? We came up with some wild examples, including a boat fuel tank sloshing around (see side viewbow view, aft view), and a wrench quench. But I was still left with the feeling that we hadn’t really shown why Compartments were so unusual.

Then, while trying to come up with ways to explain why Curved Thermal Elements were also so unusual, Tim Panczak asks, “Why don’t we do a drinking bird?” He was referring of course the famous thirsty toy that has probably mesmerized every kid ... even those who didn’t go on to become engineers much less thermal/fluid engineers. He was referring to the glass bulbs at either end, and not to all the scrumptious phase change going on inside. To each his own.

I can’t explain to friends and family why mathematical modeling can be so addictive. (I was going to name this post “I came, I saw, I modeled.” But that emphasizes the victory and not the downside of addictive engineering behavior.)

If you’re reading this, you probably get it but can’t explain it to your friends or family. So maybe you’ll appreciate a story of obsession. If not, at least have fun with the video: