How to do pics of tuft testing

[M_a_t_t]

Originally Posted by JulianEdgar

Not sure I've mentioned this here:



They are commercially available.

How important do you think the plate/puck part thickness and shape is? I used 4.75mm (3/16") flat stock. I think I was successful this time.

[JulianEdgar]

Originally Posted by M_a_t_t

How important do you think the plate/puck part thickness and shape is? I used 4.75mm (3/16") flat stock. I think I was successful this time.

That's a good question - and I don't know the answer. The professional Scanivalve one is 1.27mm thick, and mine is 4.4mm thick. I think yours will be fine. Round the upper edges.

[JulianEdgar]

In fact, I have often thought this would be a very valid criticism of my pressure measuring techniques with the puck: How thick is the boundary layer where you are measuring, and does the puck disturb that?

And the answer is: I just don't know.

Of course, flush holes in the car's body surface would be best, but that's a bit hard in your daily driver.

When developing the measuring puck, I went through a whole bunch of techniques, with Dick Barnard commenting, and this was the best I could come up with. (I'd not seen the Scanivalve one at that time.)

And, when my on-road measurements matched Jaguar's CFD, I became pretty confident.

And Cr45's suggestion (here) of using the pitot static port as the pressure reference (instead of a sealed vessel) was revolutionary. (I have, via PM, asked him for his real name so I can publicly thank him in my books and Youtube videos, but he is shy.) His suggestion took my pressure measurements to another level - indeed, a radical improvement, and a major reason for my doing the update book.

So I am now pretty confident that these aero pressure measurements reflect reality, but with the caveat that the further you are towards the front of the car (and so the thinner the boundary layer), the less valid may be the pressures.

[Vman455]

Originally Posted by JulianEdgar

Thanks for finding this; I just emailed them to see if I can buy some.

[freebeard]

...and does the puck disturb that?

And the answer is: I just don't know.

As a first approximation, the Scanivalve has a 45° chamfer.

And Cr45's suggestion (here) of using the pitot static port as the pressure reference (instead of a sealed vessel) was revolutionary.

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[JulianEdgar]

Originally Posted by freebeard

As a first approximation, the Scanivalve has a 45° chamfer.

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Yes, my puck has rounded top edges.

I can't remember when Cr45 made his/her suggestion - months ago.

[freebeard]

You could look here: https://ecomodder.com/forum/search.p...nduser&u=15140

[JulianEdgar]

Originally Posted by freebeard

You could look here: https://ecomodder.com/forum/search.p...nduser&u=15140

This was the post: https://ecomodder.com/forum/showthre...tml#post625892

A really great idea - so obvious in retrospect (but I'd not thought of it!).

[JulianEdgar]

Originally Posted by Vman455

Thanks for finding this; I just emailed them to see if I can buy some.

Here in Australia I had to go through the Scanivalve local agent. That all went well, and I placed my order (and paid for it) only to then be told there was a minimum order amount (ie $ amount) - and I'd have to double my order. I declined, so I never got any of them.

[Vman455]

Scanivalve sales got back to me this morning; in the US we can order direct from the company. The patches are $9.40 each, and there is a $75 minimum order. So, I'll have extras if anyone wants to try one.