Low Air Compressor CFM Still Works?

[yangshi]

Halfway through my thesis on a mach 2 ramjet, and I unfortunately realize that I need 50-72 CFM to test it. The only ACs I have are 2 CFM portable pancakes. Is it possible to run say a 25 CFM AC at 50 CFM for a short period of 10-60 seconds? Is there a quantitative way to find how long the AC will last above the required CFM?

I used isentropic equations to find that the required tank pressure is ~115 psi for mach 2 outlet, if that helps...

 

[Stephen Tashi]

Are you using "CFM" as a measure of volume flow or mass flow? According to http://www.truetex.com/aircompressors.htm the CFM rating of an air compressor is a measure of mass flow.

I don't know how you can run a typical air compressor at a variable CFM. I suppose the flow rate varies as you make it work against more and more pressure, but haven't seen any compressors where you can set the CFM to a specific value.

Can you get a large reservoir tank and slowly fill it with compressed air, then release the air suddenly?