Intake runner sizing..
Bruce Bowling
bowling at cebaf.gov
Thu Feb 22 19:44:16 GMT 1996
~ Looked up the basic equation, and it should work for Rotary engines. One
~ question, however. I've heard mentioned that the airflow through a
~ rotary is essentially twice its "displacement". I've pretty much ignored
~ rotaries, so I'm not sure how technically sound this is...
~
~ Anyways, here is the equation:
~
~ _c_ {_(ab+a+1)+-(((ab+a+1)^2 - 4ab))^.5_}
~ f= 2pi { 2ab(L/A)sub 1 * V sub 1 }
~
~ where: a=(L sub 2 A sub 1)/(L sub 1 A sub 2)
~ b=(V sub 2)/(V sub 1)
~ V sub 1= Vswept/2*((CR + 1)/(CR - 1))
~ c=speed of sound
~
~ CR: Volumetric Compression Ratio
~ L sub 1: Inlet pipe length
~ A sub 1: Inlet pipe area (cross sectional)
~ L sub 2: Air duct length
~ A sub 2: Air duct area (cross sectional)
~
~
I have been lurking for this for some time (I have a WWW page
just licking its chops for this info).....
A few questions:
The equation appears to be a solution for a quadratic. Is the sign
of the numerator term (ab+a+1), (the term before the +-), really
positive?
The denominator term of 2ab(L/A)sub 1, I do not see the definition
of this (to reference the "sub 1"). Or is this just 2ab(L/A)?
Is Vswept the volume swept by the piston?
Are the units self-consistant (i.e. use feet in speed of
sound and cubic feet for Vswept, and feet for lengths and
cross-sections.
Very nice info - Bruce
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Bruce A. Bowling
Staff Scientist - Instrumentation and Controls
The Continuous Electron Beam Accelerator Facility
12000 Jefferson Ave - Newport News, VA 23602
(804) 249-7240
bowling at cebaf.gov
http://devserve.cebaf.gov/~bowling
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