air flow rate???
04-12-05, 07:43 PM
#1
air flow rate???
Can someone tell me the air flow rate for a 13b in cubic FT./sec. for a given rpm? & what about pressure? assume 0-14 psi. variable. NE1 got a formula? I'm working on an induction system. I have seen that the wankel breathes about double what a normal piston motor does for a given displacement.
Thanx.
Ramses666
Thanx.
Ramses666
04-12-05, 11:54 PM
#2
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For rotary engines and 2-stroke piston engines:
Airflow Rate cubic feet/min = (displacement cubic inches * engine rpm * volumetric efficiency) / 1728
Divide the above answer by 60 to get cubic feet/sec
The flow rate is not significantly affected by the pressure. However, if you are trying to calculate the airflow rate through the induction system that is upstream of the supercharger (such as the air filter), then you need to multiply the previous answer by the pressure ratio (shown below) to get an approximation of the airflow rate through the low pressure portion of the intake system.
Pressure Ratio = (ambient pressure + boost gauge pressure) / ambient pressure
If you find this confusing, see link below, or one of Corky Bell's books, "Maximum Boost" or "Supercharged!". Just note that nearly every source is going to use the 4-stroke piston engine airflow rate formula that has a 0.5 or a 1/2 factor that you need to take out of the formula, or else you need to double the displacement of the rotary engine when entering the information into the 4-stroke piston engine formula.
http://www.gnttype.org/techarea/turbo/turboflow.html
Airflow Rate cubic feet/min = (displacement cubic inches * engine rpm * volumetric efficiency) / 1728
Divide the above answer by 60 to get cubic feet/sec
The flow rate is not significantly affected by the pressure. However, if you are trying to calculate the airflow rate through the induction system that is upstream of the supercharger (such as the air filter), then you need to multiply the previous answer by the pressure ratio (shown below) to get an approximation of the airflow rate through the low pressure portion of the intake system.
Pressure Ratio = (ambient pressure + boost gauge pressure) / ambient pressure
If you find this confusing, see link below, or one of Corky Bell's books, "Maximum Boost" or "Supercharged!". Just note that nearly every source is going to use the 4-stroke piston engine airflow rate formula that has a 0.5 or a 1/2 factor that you need to take out of the formula, or else you need to double the displacement of the rotary engine when entering the information into the 4-stroke piston engine formula.
http://www.gnttype.org/techarea/turbo/turboflow.html
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