con-trails...at 118" WC

[airflowdevelop]

Earlier today, at 63% relative humidty. I was calibrating a pitot-array. At approx 118" WC I started to see con-trails start about .500 away from the orfice plate. What was interesting...is how much flow dropped when this happened!

I currently have engines that see over 120" over the valve seat..and am re-thinking how these motors react in humid conditions. Has anyone else seen this happen? any data that exist?

this was tested with a 2" lab SEO. Will be ordering another box of the 115923's and see what occurs beyond this point.

I also will be installing a dial indictator to measure vibration in the orfice thinking possibly this could be the problem. I am sure there are F-1 guys around that have already dealt with this problem, and would like some input.

Dennis

[airflowdevelop]

ok...scratch the previous part, concerning the 115923's.

IMO even with the volume of motors, I have exceeded the max depression of these units. I added all in 100% duty and can not pickup addition depression. Any ideas on what motors in volume will exceed this depression? I know the 23's are rated at something like 101"? But they out-perform in quantity. Is their something that is rated at 120", that should be fine for what I am doing.

[bruce]

Man thats some flowbench if you can pull 118", I'd like to stop over and see it sometime? I'm just down the road from you in Lancaster County . . .

[airflowdevelop]

You oughta see what 100" does on 4 square foot of 3/4" MDF...DUST EVERYWHERE!

no longer have those problems. Structuraly reinforced! Although need motors that pull above 120" 's

I know where there is a 12:71, may give a shot.

Bruce,
I am the dumb slope that asked you for the help assembling the bench (remember)?
I'm not that good when it comes to wood...if you know what I mean! Currently we are working on some SCCA projects that restrict people from entering the shop (I know, but I don't make the rules!) by next month they willl be gone, let me know and we will get together! Would be my pleasure, I will bring the steaks and beer.

Dennis

[gofaster]

[airflowdevelop]

Jim,
Thanks for catching the typo...should be 102 not 120.

I have found the problem. It seems that the SEO is vibrating that bad that it is erroding (sp?) the plastic sleeve I have it fitted into. Even though I can't measure the vibration, If I touch the plate with a screw driver it sounds like a dentist's drill..Plus now the plate is distorted!

Looks like I broke my air handler again, so back to the drawing board!

Dennis

[Jesse Lackman]

So you think the flow drop is being caused by the vortex, or the orifice plate problem?

Was the orifice plate buzzing at other depressions and humidity levels?

I wonder if it is a visual of the air forming a tornado or whirlpool of sorts, like water going down a drain.

The humid air just made the tornado or whirlpool visable.

Contrails (a vortex) can form at jet engine intakes, that is not so unusual, it probably has more to do with what the air is doing outside the inlet, I'm kind of skeptical the orifice vibration has anything to do with it.

If you want more depression I would look into gas ring compressors, sometimes called regenerative blowers, if I ever build another bench that is what I will use.

[bruce]

[airflowdevelop]

Jesse,
You know, I am not sure. When I touched the inside of the SEO, the flow would go up. It is a 1 square inch (dang, I wish these forums worked like word!) SEO so it does not take much until you are becoming a restriction, but even with a #2 phillips screw driver on the inside, the flow went from 74 cfm without back up to 113 with it not vibrating. after 3 tests the plate worked itself loose by atleast an 1/8th". After tightening everything back up, the issue went away (but the orfice is still screwed up.)

Dennis

[Mouse]