Re: air flow #s ?
 

Absolutely the weather correction is key. But correcting simply for density will get you 97% there. Yes, there are small differences. But there should not ever be large differences if both flowbenches are quality pieces, calibrated and properly operated. Of course you will see small variations... But a while ago, there was a dicussion that so and so's flowbench reads 275 CFM, while some other guy's reads 250 Cfm, both at 28"... THat is just plain garbage data there... One of them (or both, with one higg and one low) is clearly WAY off.......

And Yes, NASA, Boeing, Airbus, and any steam turbine/gas turbine manfuacturer gets it, and does it right, thats for sure.

And regardless of the density, the square law is... well a LAW :D (sorry, had to get that in one last time ;) )

Good conversation, gents.

PS: Adger, I have the same sort of books on my nightsand too... My wife thinks Im nuts... She says "nothing like a little "light" reading before bed, huh hon ?? " ....


Kevin

Re: air flow #s ?
 

Funny how so many of us are cut from the same Cloth. & yes my wife will be reading her favorite paperbacks when I'm into the "HD" reading!! LOL!

Re: air flow #s ?
 

Going from memory here, but the 25, 28, 35, etc debate is related mean inlet Mach number. Higher test pressures I think will be more realistic to real world conditions, especially at high rpm/flow numbers or low lift flow.

Re: air flow #s ?
 

Chris,
You are correct in your statement.

Re: air flow #s ?
 

In my case, I am sent to sleep in the guest room. :)

Re: air flow #s ?
 

great discussion. let me throw this ? out. if you had a port flowed at 25" and let's say it flowed X.CFM, then changed to 28" [all else remaining equal] and checked the port, would it flow more or less?
thanks Rod in AZ

Re: air flow #s ?
 

Sure, it would flow more, and to be precise, it would flow the square root of (28/25) times the original X cfm..

And that right there is what started this thread off in the first place !:D The square law of compressible airflow !!! ;)

Kevin

Re: air flow #s ?
 

Kevin,
Using math to extrapolate from 25 to 28 is correct. The laws of Physics allow us to do that, but you assumed there was nothing wrong (called a Problem) with the port that the increase in air speed didn't magnify or make show up.
There, that is the Real World problem with extrapolation and with assumptions.
As I've said or aluded to.... That is one of the reasons why there is a lot of salesmanship in below 28 numbers. There is no way in He** I would buy a head that was flowed @ 10 or 25 or anywhere in between and the numbers extropolated up to another flow number. That is IF I was buying based solely on flow numbers (which I wouldn't do, not a good idea!)

Re: air flow #s ?
 

It's kind of like using barometric pressure, humidity and temperature to predict ET without taking into account oxygen content in the air.

Re: air flow #s ?
 

x10!!!