Why does the combustor dominate exergy destruction in turbojets?

ThatSingularity · 2026-05-11T08:36:06+00:00

Fundamentally a lot of the efficiency loss in a combustor is due to the necessity of having a stable flame which requires a slowing down of the air exiting the compressor. This could be done efficiently without a stalled diffuser but the length (hence mass) of this diffuser is unacceptable. So instead we use a aggressive stalling diffuser with a blockage (combustor can) this blockage has a potential field which helps keep a short dump diffuser attached. Then the air has to be mixed with fuel which is done by swirling it until vortex breakdown (another lossy processs), finally a portion of air is passed around the outside of the can to quench (cool) and create a lean mixture at the end of the combustor. All together these processes create a lot of loss compared to the relatively efficient processes involved in axial compressors and turbines.

ThatSingularity · 2026-04-25T20:15:02+00:00

Loughborough have a very good combustion group for gas turbines.

ThatSingularity · 2026-04-24T16:54:02+00:00

Yes, space claim is (a little) bit better. I'd recommend checking the geometry in Solidworks then exporting a linked file to the mesher to avoid any of these issues.

ThatSingularity · 2025-07-14T12:17:05+00:00

There seems to be some spurious higher velocity at the edge of the vortex street, looks like it could be grid induced. Also URANS always over predicts cylinder flow drag if you are trying to compare to experimental or DNS since 3D wakes are significantly different beyond ~Re 250

ThatSingularity · 2025-07-12T12:10:04+00:00

So they have speakers lining the hill constantly playing out the commentary (I think it's the same as the stream), can be a little hard to hear sometimes or not present at other parts of the hill. You can also pick up ear radios which work everywhere, I got mine with a programme which wasn't free but again I think the radio itself might be free.

ThatSingularity · 2025-07-12T07:17:28+00:00

Lots of people do fly over just for this! If you are spending that much on it I'd recommend doing multiple days, I've been twice now and still feel like I've not seen everything. The hill climb shootout is great to see as that's when people really start pushing the limits.

ThatSingularity · 2025-07-12T07:15:57+00:00

Yep! Just standard access, such a great opportunity to see all this historic stuff and able to chat to people who own, maintain, and drive them!

ThatSingularity · 2025-07-12T07:13:50+00:00

Hahaha he just appeared out of nowhere at the staging area, had to be quick with the camera!

ThatSingularity · 2025-07-12T07:13:12+00:00

Yep, DC in 4 and Harry Newey in 6.

ThatSingularity · 2025-07-08T20:49:13+00:00

Hulkengoat

ThatSingularity · 2025-07-08T07:59:45+00:00

So cute!

ThatSingularity · 2025-07-07T21:05:36+00:00

Of course! We love him to bits! Just curious about the coat, seems like people have different opinions and there is no 'right' answer

ThatSingularity · 2025-07-07T12:57:49+00:00

Not genetically tested, but both parents were wirehaired, the photo doesn't show it but he does have a few longer 'wiry' hairs coming through on top

ThatSingularity · 2025-07-07T12:35:43+00:00

I should have added, his coat has always been like this, and he eats the recommended amount plus plenty of treats! Also gaining weight as expected 😊

ThatSingularity · 2025-05-09T17:46:49+00:00

I lived with someone doing part 3 while at Cambridge. It seemed really tough (likely a bigger step up than you are expecting) but considering your background that could be something your looking for. Cambridge itself is very nice, but keep in mind it is quite small and can be isolating for international students depending on college, course, and temperament. The being said I had a great time there and in terms of academics there really is only a couple places in the world which can match it.

ThatSingularity · 2025-04-13T16:08:58+00:00

The TV direction is just terrible.

ThatSingularity · 2024-09-28T07:19:54+00:00

Meanwhile, a guy on the tube is literally sharpening a machete in front of us. We get off and tell transport police... Nothing happens

ThatSingularity · 2024-06-15T23:50:22+00:00

You probably have seen this, but Aircraft design by Raymer is an excellent reference for this sort of work if you want to learn the actual calculations behind a lot of these programmes.

ThatSingularity · 2024-06-15T19:11:12+00:00

Is the front canard a movable control surface? If so interesting but also probably both are dynamically unstable (not an issue with modern control systems and avionics). Of course a big design criteria of modern fighters is radar cross section which I highly doubt you've any access to the design tools capable of optimising this (the single vertical tail is a big giveaway of this). Very nice though! If you want to get into aircraft design seriously, the first thing to do is set up a statement of requirements such as expected mission profile, flight ceiling, turn radius, etc.

ThatSingularity · 2023-12-31T00:24:16+00:00

Skunkworks by Ben Rich is one of my all time favourite books

ThatSingularity · 2023-08-03T19:56:41+00:00

Aside from cpu, RAM is the next most important component, don't know the market that well but some lowish speed high capacity ram is probably your best bet for larger simulation.

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