Pingu's Next Project - A Flowbench

[Mignon]

If you'd bothered to look and see what it did instead of just assuming a circ message meant an error you'd have seen it updated the Reynolds number to the last value calculated every time you pressed calc until it stopped changing and was hence the correct value. It was a clever bit of programming which you've just replaced with the time consuming manual procedure it was specifically designed to avoid. But you assumed instead of checking which makes you sloppy and careless and even worse was your first assumption was that I must have made a mistake. OK so there was once that time many years ago I panicked briefly that I'd made a mistake but luckily it turned out I was wrong.

[GreenV8S]

Mignon said:

OK so there was once that time many years ago I panicked briefly that I'd made a mistake but luckily it turned out I was wrong.

[AW111]

There is a "goal seek" iterative function in excel, designed for exactly that purpose, but it's a while since I've used it.

[Mignon]

I'm a dinosaur. I still use the DOS based spreadsheet I learned on 30 years ago.

[AW111]

Mignon said:

I'm a dinosaur. I still use the DOS based spreadsheet I learned on 30 years ago.

There are plenty of workshops still using DOS software I wrote 25 years ago...




Cheap bds

[pingu393]

AW111 said:

There is a "goal seek" iterative function in excel, designed for exactly that purpose, but it's a while since I've used it.

I'm not sure what program Mignon used to write the program. Excel will allow you to load it, but it won't allow you to write it without warning you that you are creating a circular reference.

I've just amended the program to use goal seek and it works.

Mignon's sheet has two Reynold's Number cells, REYNOLDS NUMBER START POINT and REYNOLDS NUMBER CALCULATED.
I've deleted the formula in REYNOLDS NUMBER START POINT. It is now just a value.
I've created a new cell that subtracts REYNOLDS NUMBER START POINT from REYNOLDS NUMBER CALCULATED.
I've used "goal seek" to change the value of REYNOLDS NUMBER START POINT until the value of the new cell equal ZERO.

[Mignon]

I wrote it in about 1991 in Borland Quattro dos spreadsheet.

https://en.wikipedia.org/wiki/Quattro_Pro

This would run on every operating system I've had up to Windows XP but had finally met its match in Windows 7 on my current pc so I now have to use DosBox 0.74 to emulate dos to run it. I'm therefore trying to convert to using Quattro X7 for windows but I think old dog and new tricks I really don't get on with windows spreadsheets.

[pingu393]

The flow bench...

https://youtu.be/5G-cnCadl5c

It gives consistent results. I need to shorten the upstream pipe and I have a straightener at the ready.

[Gtxxjon]

Well done Pingu!

There is some pretty scary mathematics going on here in this ‘old’ thread lol.

I suppose it goes back to the David Vizard ‘cheap as chips bench’?
He used a few parts that he had laying around and worked out ‘what to do’.

So fifty years on he still says his £50 mini engine engine bench is still valid...

I am gonna try the same experiment in the next few days on a Big block Mopar engine.
If it’s a complete flop, I will endeavour to build a bench lol.

If all this fails a pro-bench will be sort after, but in 50 years of engineering, I have never seen one for sale?

John

[pingu393]

It only gets difficult if you want to build a bench that produces ABSOLUTE results that can be compared to other benches.

It's very easy to build a bench that compares RELATIVE results.

Vizard's bench is a RELATIVE test bench. He only compared his own modifications. Nothing wrong with that at all, and it's where I started - and probably should have stopped . I just found myself going down the rabbit hole of trying to make something that could produce results in SI units, rather than Pingus of pressure

Good luck with your project.