It's a bit OT, but it IS related to model making (I'm making a new burner for my foundry).
Air flow through pipework when pipe size is reduced.
I have a centrifugal blower which outputs a large volume of air at a relatively low speed + pressure.
The output on the blower is 4" diameter. I need to reduce that diameter to around 2".
Before I get the tin snips to make the reducer, I could do with some advice, I don't know enough about fluid dynamics or whatever it's called to do a google search!
1st. I'm guessing that the smoother the transition from 4" to 2", the better? I'm thinking of a cone around 12" long, rather than one of 6"?2nd. What will happen to the airflow? I'm guessing that I'll get a faster airflow, but lower volume? (like putting my finger over the end of a hosepipe)?
3rd. The pipe size reduction notwithstanding, if I want to reduce the amount of air flowing, should I throttle the input? the output? or would a rheostat to vary the motor speed be best? The blower has a seperate cooling fan, and does not depend on airflow through the blower to cool the motor, if that is relevant.Any help would be appreciated - thanks!