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evolcire
01-20-2006, 12:49 PM
Just trying to learn here, so excuse the ignorance...you'd think I'd know something like this after 2+ years in undergraduate Mechanical Engineering...

What exactly is a turbine housing? Am I right to assume that it directs the exhaust flow into the turbine...

Then, what is the function of the flapper? And how does a single flapper perform better than a twin flapper design?

turbolarry
01-20-2006, 01:31 PM
What exactly is a turbine housing? Am I right to assume that it directs the exhaust flow into the turbine...

Yes it's the side that handles the exhaust and spins the turbine;
http://linux.forcedperformance.net/merchant2/graphics/00000001/full/NTEVO8001_full.jpg
http://linux.forcedperformance.net/merchant2/graphics/00000001/full/THEVOMR105001_full.jpg



Then, what is the function of the flapper?

The flapper opens and diverts exhaust around the turbine once desired boost pressure has been reached (internal wastegate).



And how does a single flapper perform better than a twin flapper design?

I wonder the same thing.* Is there a significant difference?* 10.5cm/sq. is still 10.5cm/sq.* Is there really going to be boost creep with the dual flapper vs. the single.

trinydex
03-21-2006, 06:38 AM
it's not about boost creep but about more smooth flow, less turbulence.

altho this is a typical regurgitated answer i have to ask myself if the turbulent flow is a bad thing. mech es should know that turbulent flow usually gives rise to very fast and relatively uniform velocity profile due to the mixing of the fluid. this should technically make things more uniform as the boundary layer doesn't interfere with viscous losses as much. however i'm sure there's a part of the discussion that i'm missing as turbulent flow probably has it's own inate viscous losses and the mixing especially when joining other flows is probably very disruptive.

back the to subject at hand though, the flappers of either design have no problem getting rid of enough exhaust, but it seems to reduce backpressure slightly to run the single flapper.