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Post by bigshingle on Dec 1, 2008 10:26:51 GMT -5
Now you've made it more complicated, Stew.
I like the idea of attaching the crankcase breather that way, but what happens to the turbulence when you put a hole in the side of the pipe and inject oil fumes?
Still, I predict the flow of air to my lungs through my nasal passages will be improved and my clothes won't smell as strongly of oil smoke after a lot of stop-and-go riding.
I'm going to try it.
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Post by StewRoss on Dec 1, 2008 14:41:30 GMT -5
Heh, heh...so long as it doesn't protrude much into the duct it shouldn't make much difference really...look at pic 9 as well. That one is made of alloy and it fits between the carb and the fliter. You could make that so it had basically no effect, or negligible, by welding the breather spigot tube onto the outside and having it flush on the inside. Don't forget that there is a ledge on a normal carby where the filter clamps up to the end of the carb anyway...unless the carb's inbuilt bellmouth rounds right to the end, like in a TZ carb I have on the Black Cafe Racer... SR  |
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dutchcool
Full Member
-1981 SR500-
Posts: 104
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Post by dutchcool on Dec 1, 2008 16:38:08 GMT -5
Thanks PC! Try my best. Realized after reading through the posts that I hadn't addressed the Coanda effect. bI dont think Coanda really applies here. The Coanda effect is a very subtle thing in the field of fluid mechanics and can be very contentious ( I am setting myslef up here I think !!) . I think Dutchcool is referring to the tendency for concentrated jets to stick to convex surfaces. This is exactly what Coanda observed as he lit his plane on fire with a turbojet exhaust of some sort I elieve. Basically, a jet will "attach" itself to a surface and follow the contour of the surface instead of staying directed in a straight line. This effect arises because of the interaction on the jet with the surface. The jet will scrub off momentum at the surface. If you look deeply into the governing equations you find that the momentum loss will result in a loss in pressure also -- makes sense, the flow looses some energy. So, there will be a pressure gradient driving the jet towards the surface -- the jet stays attached to the surface. However, in the SR carb inlet case, the incoming flow is not a jet (see my post above) and enters substantially laminar. An entrance flow such as this can stays attached to severely contracting geometries. There is no Coanda effect here. On an exit flow (downstream of the carb for example), we are limited to just less than about 10 degrees of divergence before the flow will separate from the wall and cause all sorts of trouble. Note that this is different than Coanda since there is no real concentrated highly energetic jet seeking to attach itself to a surface. Bill-- reading more about the subject learned me that the Coanda effect is taking place behind the venturi ( see bottom lines ) : 74.125.77.132/search?q=cache:xjPAklwHXGsJ:www.aeronautics.ws/blunder5.html+coanda+effect+in+carburator&hl=nl&ct=clnk&cd=3&gl=nl&client=firefox-aSome entertainment on this subject ! : nl.youtube.com/watch?v=ggUIJDgkSSs |
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