Turbulance good or bad

[obi_waynne]

When thinking about the air intake into an engine is turbulance a good or bad thing?

I've always thought that you want the air to get in as quickly and smoothly as possible.

Now I'm starting to think that turbulance aids the vapourisation of the fuel.

Both can't be true unless there are points of the intake where turbulance can be introduced and then it can be smoothed out again.

 

[HDi fun]

Good and bad turbulence I suppose.

 

[Ronbros]

my take on the ques, as little turbulence in the inlet ports as possible , smooth flow, but when air flow gets into the chamber, past the valve,
( of interest,the valve is the most restriction in the whole flow path).

and this old english guy said to me, the bowl/pocket shape can really help get flow into the chamber!

yes
you do need good turbulence in the chamber,so as to mix the air and fuel homogeniously,squish and quench help the process, that way the flame front can move evenly!!

BUT all that goes out the window with petrol Direct injection engines(DI), most seem to operate with two areas of combustion, one in center of piston,light throttle, and using complete chamber at hi-output.
some serious engineering going on there ,READ diesel theory!

i'm starting to get carried away with this,, over&out.

 

[Ronbros]

waynne, the fuel as a liquid cant burn well, but when the fuel droplets get hot they turn from atomized liquid to a vapor ,now they can light off.

that is precisely why DI was finally put into use,on petrol engines,
altho Germany had it in 1930s.

DI uses very hi pressures, just to reduce the size of a fuel droplet, that way it goes from atomize to vaporize faster!
as you raise the injection pressure, the size of the fuel sphere gets smaller,(there are formulas for it).

there are many good books on the subject available