Maybe testing back cuts and/or turbulence flow over the valve head.
I would guess you are right, Frank. I just don't know how much I would be able to tell by the smoke pattern. That is, how would you interpret it, since it is visual? Would Smokey just be looking for the smoothest flow and assume that is best? Or something else? I don't know.
paulie
I think the way Smokey approached things, he tried to leave no stone, unturned and my only guess, as I stated, was he was looking for clues, in how the back cut and valve head worked, if it was me, I would also have been testing different margin shapes, too and I doubt that he would over look that either.
Whether or not, it would be directly applicable to a port, I can't say as port velocity is much higher and differently shaped than his a open tunnel. That said, aero flow has been well documented, since the '30's and most aero flow has the same basics. We wouldn't still be using poppet valves if, there was a more reliable way to open and close the opening.
Between '78 & '80, I worked at ELLCO Engineering (AKA Experimental Engineering), in Irvine, CA. In those years, we worked on the stealth and cruise missile R&D programs. I wasn't a Model Maker but, work directly with them, doing the machining needed. I made supersonic wind tunnel models, out of solid PH17-4 SS for the Tennessee wind tunnel and templates, used in "splining" the subsonic models. It was extremely interesting stuff and I went on to study aerodynamics, while I work there and to make the plug, mold and the finished rear wing, on my race car below.
Two of the things that I learned, that apply to porting, is that all transitions need to follow a radius and when transitions exceed 12 deg, stall will kick in at that point or shorty after, w/o something else to control it. In wings, that would be a slot or slat. Another thing that impressed me, is the difference between subsonic and super sonic flow. They need COMPLETELY different designs and I assume, what you hear in a port, when it gets "noisy" is the turbulence of transonic flow, if it's approaching that speed or just turbulence, if not. As I understand it, good port flow, is <300 fps and transonic is around 8-900 fps. I'm not a porter and have never ran a flow bench, maybe Joe could speak more to that.
