@db

Adding ribs for extra heat transfer surface makes perfect sense. Odds are that they would work just as well (or better) if they were straight vertical ribs.

But once you put the thing in a CNC machine, you can just as well make a fancy shape

@db

See this for example:

@db

The glitchy shape is genuinely how the impeller of a turbocompressor looks like. I cant judge if the shape is accurate, but it is drawn by someone who has at least a basic idea.

Technically that doesn't make much sense - that turbo shape is designed with a surrounding housing in mind. And its aim is to generate forces and reduce losses, neither of which are relevant here.

At a guess, the effective part is just adding surface area and the complicated turbo shape is for show?

@pluralistic
Grandma

♨️ Researchers at EPFL School of Engineering have shown theoretically that, in highly ordered materials, heat can flow toward warmer regions without violating the laws of thermodynamics. Their work could help design electronics that minimize heat loss.

Read more: https://go.epfl.ch/c7fd48

#EPFL #Thermodynamics #Electronics

@littlealex @toxomat
That's far from obvious! The FCAS project is collapsing, which seems driven by the belief of Dassault and the French government that working with Airbus is only delaying the project. The German government is buying additional F35s (and rumours about joining gcap) suggesting that they are not convinced either.

Note that Airbus-the-aircraft-manufacturer is not involved much. They got burned on the a400m and dont want more. Its their missile subsidiary mostly

@littlealex @toxomat
Yes, I know. But there is no more experience, neither personal or institutional, in running an entire project. That comes with a great risk that a project spins out of control, unable to meet the exlected capabilities, costs and timelines
until it gets cancelled.

Imagine the F35 project with its setbacks, but now run by people who never did that before, and the costs divided among multiple distrusting governments, who also have no experience managing such a project...

@littlealex @toxomat

I dont know that we could do the basics tough? The last European jet fighter development projects were in the 1980s. Eurofighter, Rafale, Grippen.

Basically, if you worked on the development of those planes as a first job out of school, you're now pushing retirement age.

Okay so an interesting quirk of my #3dprinter (if you can call it that) is that the fans are adjustable up and down. Since I have no way to CFD the design quickly, I've never really known where they should point or be installed to. I have just guessed and tried locations.

Are they too high (ineffectual and cools the heat block/nozzle)? Too low (cools the part, at risk of snagging or dragging on the print)? Tough to say!

And an idea just hit me. I have a thermal camera! It's not perfect but I can crank everything up to temp and dial in the range of the thermal camera to see the effects of cooling on the block/nozzle. And it should be way way faster than modeling and doing #cfd on this design.

I don't know if the active heater will be a problem but I think it SHOULD work! Right?

#nerd #someLikeItHot #noNoTooHot

@mkb @futurebird @Lana

My grandparents were born in the 1920s ,and the world changed enormously from their youth to that of their children. The changes from my youth to that of my children are very, very minor by comparison.

I keep coming back to that, whenever people talk about supposedly accelerating technological change.

@TimWardCam
There must be a myriad answers to that, right? True accounting is always some specialised software package, with or without customizations and links to other systems. The spreadsheet area is more in forecasting and budgetting.

Forecasting tends to be a dangerous area for excel errors . It has fully automated parts (these fixed cost will continue) but also adhoc inputs and assumptions that need personal excel tweaks. Then the tweaks harm the automated part that no one verifies

@TimWardCam

The great things about spreadsheets, is that people can do their own, mildly complex programming in it.

A nice, even superior alternative would be that some expert makes a dedicated program in some other system, and that expert also sticks around for maintenance and mods.

That alternative is rarely on the table! And even those rare occurrences already eat up a good chunk of all software dev, as the OP notes.

Someone else mentioned "bank python" a solution to this problem...

@TimWardCam

The theory is that the ERP or accounting system gets additional features that provide the required insight, all properly engineered.

But that's a Project, even for the tiniest change . It needs budget, oversight, a contractor, some internal and external meetings, etc. For most useful features, this wont happen. Its in the core system, or you wont get it.

So people claw to their spreadsheets. If you hand control to the IT people, you're done. Black box, no touching, get a ticket.

@TimWardCam @david_chisnall

I have seen these spreadsheets and often heard the (very valid) problems that professional software people have with them.

The serious problem with getting it engineered properly, is that your critical tool is now maintained by some outsider. Another department or an outside firm, often with vendor lockin. Every modification that was 2 lines in excel is now a budget request, some meetings to explain, a waiting period, tests.

@woo @kibcol1049

It depends a lot on scope. Its quite common to need some work to make space (indoors out outdoors), or modifications to the heating system to allow lower temperature water, or some extra isolation works.

It's pretty easy to add some thousands that way.

And most people won't get the sharpest price possible. They go with a trusted local supplier who is more expensive, or they get a bit ripped off, or even both.

@TwoClownsEating @blueorangeblue

Thats a fair price, a scale model citygo is about the same size as a real one.

@EricChrSmit @albertmantingh

Tuurlijk, maar is dat zo erg? Dit soort gladde lui kunnen handig zijn, als ze ruwweg aan dezelfde kant staan.

@exador23

Vague theory on 'low resistance': a fan in free air (no outside resistances) still has o accelerate air through its own disk, plus some associated losses and swirls.
This is (very roughly) like a pressure loss of v^2, where v is the average velocity through the disk.

So even a low-pressure fan is designed to deliver that kind of total pressure, or it would deliver no flow at all.

If you add resistances of that order, the fan stays close to its no-resistance working point

@exador23

Keep the exhaust opening ( fan or not) above the heat source. Exhaust air must be the warmest in the box, for max effect.

Low inlet is best, but cold air will circulate internally to the bottom anyway. As long as you avoid a short circuit where cold air mixes with heated air on its way to the exhaust.

What about 0 fans? If equipment can run in free air, it can run with large enough openings. Slots can be easier to add than square fan openings

@exador23

For a 'low resistance' situation, a single fan (in inlet or outlet) will move almost the same air volume as a push-pull system (fan in inlet and outlet). 2 fans in parallel will move much more.

Rough estimate: your system is 'low resistance' if the opening without fans has at least the same area as the fans, and the flow path in between is never smaller than twice that area (preferably more)

If you use a dust filter, 'push' is beneficial. Otherwise, push or pull are fairly similar