First off, this is not a newbie question. I understand fully about timing, overlap, reversion, pressure and sound wave tuning etc. And how to port a rotary.

What I have noticed and have only seen is were the port opening in the side housing inside the engine (port face or opening, not were it bolts to the manifold but what controls timing) always seem to be ported with somewhat sharp edges. Has anyone tried to add a small radius around the entire port opening (say .125 around open and closing, but smaller like .08 near oil ring side? It would be equivalent to a multi angle valve job common to piston motor heads. There are no draw backs in a piston motor with multi angle valve job, you gain efficiency, power, cleaner burn, more evenly homogeneous mixtures etc. due to a better cylinder fill using the Coanda Effect. The Coanda Effect is when air travels over a rounded surface, it tends to follow that surface rather then traveling in a straight line. (see pic). Has anyone tried this on a port? if so, what were the results like? I am hoping I won't be the guinea pig for this....lol. It just makes sense, it should fill the combustion chamber better and more homogeneously. Input anyone?

~Mike................

 

hmmmm the more i think about it......

Maybe the sharper edged common port is to keep the air/fuel mixture from contacting the side walls were the fuel will stick ( as in some two cycle motors, the intake ports are designed to "shoot" the air fuel mixture into the combustion chamber, but away from the opened exhaust port). Maybe the port is designed to keep the fuel rich pocket centered in the compression stroke near the rotor face tub? I'm just thinking aloud. Perhaps with the radius port a lot of the fuel won't burn due to being to close or sticking to the somewhat cold side housings and / or not burn complete near either end of the rotor tips.

~Mike.........

 

NO ONE?!?! Did I stumble on a porting secret you don't want to share?

~Mike...............

 

It depends if we're dealing with laminar flow or turbulent flow.
That "Coanda Effect" sounds like something only applicable to laminar flow.

Why don't you try and it report back with reults?



-Ted

 

Actually, turbulent flow is less prone to boundry layer separation than laminar flow, hence the disruptors near the leading edges of modern aircraft lift surfaces. This can also be seen on the bodywork of some recent racecars.

-ch

 

elaborate please

 

Who, me? Or the guy with the port idea?

-ch

 

Yes, turbulent flow is less prone to boundry layer separation than laminar flow, at the expense of drag. Better to fly slow like a bird than fast like a rock. Anyways thats aerospace side of me talking.

QUOTE RETed: "Why don't you try and it report back with reults?



-Ted"

LOL.... I find it really hard to believe no one has done this. I guess if its a great practice to do to rotary engines people consider it their secret and aren't posting. I really thought this would generate good discussion with some hardcore engine builders.

I just might be the "Guinee Pig" then........or rather my engine will be.

~Mike........

 

double post