The shape of the port job in the Rick Engman's threat got me thinking. The rotary offers the benefit of continous exhaust flow from one chamber to the next. Granted it isn't steady in terms of intensity but continous. I remember some earlier threat were the importants of an abrupt port opening was mentioned as a benefit to really excel the gas flow. Proberly tuned that might help scavenge the exhaust port but wouldn't a continous flow be more beneficial (especially to spool a big turbine wheel.) Also it might eliminate some of the reversion problems.



What I am trying to describe is that a curved exhaust port opening might keep the exhaust flow more continous and will equalize the pressure somewhat. While the exhaust stroke comes to an end the exhaust gases left in the chamber will be pushed out by the rotor where exhaust flow will have slowed down. When the next apex seal crosses the opening line of the exhaust port it will speed up exhaust flow in the port tremendously. Crossing a straight line will introduce a very abrupt and immediate increase in flow and pressure while a rounded exhaust opening will introduce the next exhaust cycle more gradually.



Any thoughts or theories?



CW

thanks for starting a new thread so others can enjoy https://www.nopistons.com/forums/pub...IR#>/smile.png



i think there is a lot to be learned from simply looking at rick's work, i'm all about a discussion on this https://www.nopistons.com/forums/pub...IR#>/smile.png

That's altready wrong...





-Ted

Ted

I shared my thinking would you care to share how you arrived at that conclusion?

Everyone always talks about round. How about more of a ramp with a straight opening and closing. It does the same thing but without adding so much timing. https://www.nopistons.com/forums/pub...DIR#>/cool.png



GregW

I believe the stock ports are like this. Straight line with a bevel.

This is so typical of his replies. It makes me feel like I'm on the other forum.

i second that.

even if it's not intended, it feels like cynism.

not helpful at all.

since noone really dares to think out loudly, i'll try...

let me swing my magic stick and write something that contains 100% pure fantasie and 0% hard data or anything real-world related.



my guess is, that a round opening-line helps to distribute the exhaust more evenly over the exhaust-phase, thus getting a more harmonic exhaust cycle with less reflections.



lets describe two scenarios



abrupt opening:

the exhaust gases are under enormous pressure. the sudden opening lets the gases shoot out of the chamber through the port at once. the exhaust-pulse hits restrictions (exhaust manifold, turbo.) and gets reflected towards the chamber, while the rotor wants to push out the rest of the gases. seems unharmonical to me, and a lot of energy (velocity) is wasted wehn it fully reaches the turbine.



"soft" opening:

the chamber gets purged gently, thus the exhaust gases are forced to remain a tad longer in the chamber. the first small dose of exhaust reaches the turbine, and THEN the big rest follows which doesn't colide with a hard, previously reflected exhaust pulse.



bascily i second z8cw's theory. it's about getting continous exhaust flow, like a compressor, not pulsed.



flamesuit on https://www.nopistons.com/forums/pub...>/rolleyes.gif

I am so intriged by Rick Engman's exhaust port shape. I have never seen it before. I think it is worth to theories and maybe come up with something that makes sense.



Below is Rick,s exhaust port.