Technical Ice In Venturi Of Weber 3032/dmte

[uno_jens.]

I still don´t think you can comapare the both. untill I get some real facts.

The "windchill" factor is that you transport energy faster away from your body to the sorroundings..compared to 0 velocity.
If you stay naked outside in the storm at 10 degree Celsius you wont frooze to ice.. You only think that it is coolder than what it is.. There is still 10 degree C and this is called the windchill factor.

The venturi works in a different way.. 10 deegre air entering the venturi at a certain velocity.. in the middle the velocity is very high. The energy principle say or bernoulli equation: "The sum of the pressure, kinetic and potential energies of fluid particle alon a streamline is constant."

So If the velocity is very high, the pressure must be very low..
high --> low pressur --> lower temperature..

 

[Chas Uno]

I still don´t think you can comapare the both. untill I get some real facts.

The "windchill" factor is that you transport energy faster away from your body to the sorroundings..compared to 0 velocity.
If you stay naked outside in the storm at 10 degree Celsius you wont frooze to ice.. You only think that it is coolder than what it is.. There is still 10 degree C and this is called the windchill factor.

The venturi works in a different way.. 10 deegre air entering the venturi at a certain velocity.. in the middle the velocity is very high. The energy principle say or bernoulli equation: "The sum of the pressure, kinetic and potential energies of fluid particle alon a streamline is constant."

So If the velocity is very high, the pressure must be very low..
high --> low pressur --> lower temperature..

Again, I'm no physicist so don't quote me, but maybe it's a combination of the two things mentioned?

Just like standing in a breeze, a person will feel colder and the skin temperature will fall compared with standing in the same place but with no breeze. The persons skin will have an ambient temperature, but the skin temperature will fall as the breeze passes over the skin because of the windchill. The breeze passing over the skin surface is actually REMOVING heat, and by doing so causes the actual temperature of the skin to fall. This can be measured scientifically with a thermometer!

This is the same way a carburetor has an ambient surface temperature inside, but when the air travels through it (wind chill) the ambient inner surface temperature will fall below that of the static temperature. This cooling of the inner surface will then allow any moisture in the air to freeze upon contact if the surface drops below freezing, and it is this very factor that causes 'icing to occur'.

That's my understanding on the subject, though as mentioned it needs a real physicist to explain it fully/ correctly! Then again, I am not clued up on how air pressure can affect temperature, so I'd better say nothing more!

Saying that, 'low pressure' in winter normally means it is warmer than when 'high pressure' occurs But it could also be due to air density as well as velocity, as for instance, if you travel up a mountain the air is less dense therefore the pressure is also lower. And the further up a mountain you go the cooler it gets.

However, I'm TOTALLY out of my league here so I'd better stop as my field of specialism is bio-science not thermodynamics or meteorology. Where's Paul the Negotiator when you need him?!!!

 

[jaba]

I have finnaly found some time to dismounth airbox to check trapboard and bi-metal, and my verdict is that bi-metal is not working properly and since this trapboard is lifted by vacuum from carb which opens when bi-metal opens hole between airfilter and carb. So if bi-metal doesn`t work no vacuum to lift the trapboard. Thanks for advice.

I agree with uno_jens. Pressure in Venturi is very low but speed is near speed of sound (800 km/h), so according to Bernouli equiation air is very fast and temperature is low, so it is needed to be warmed by air from exhaust manifold.