Airflow volume question...

We had dual 2" eyeball air vents in my instrument panel, on the left and lower right side. They were fed a supply of outside air, ducted in from a belly scoop using a single common 2" flex tube. They were then split, using a "Y" fitting.

One eyeball had to be removed to make room for the prop control and throttle linkage going forward.

Here is the question: with only one eyeball outlet, will the discharge volume drop by 50%, or will the total volume be the same but the velocity sped up two times in order to escape through a single outlet?

A little bit of both depending on where the Y splits the flow. The further the Y is from the intake the less total volume change you will see.
I think the bigger issue will be the distribution of that air in the cabin.

pa38112 said:

A little bit of both depending on where the Y splits the flow. The further the Y is from the intake the less total volume change you will see.
I think the bigger issue will be the distribution of that air in the cabin.

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The Y was between the two eyeball vents, very far downstream from the intake.

TXFlyGuy said:

...Or will the total volume be the same but the velocity sped up two times in order to escape through a single outlet?

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I believe this statement to be the most accurate, although I believe both would be reduced slightly due to the higher resistance of the single tube and outlet.


Best regards,

Tommycat said:

I believe this statement to be the most accurate, although I believe both would be reduced slightly due to the higher resistance of the single tube and outlet.


Best regards,

Click to expand...

Thanks. That makes sense.

The total flow will be reduced. The velocity will less than double to match the total reduced flow.

If you knew the lengths then you can get a more accurate answer. The resistance goes up by the square of the velocity (pressure drop per unit length). Removal of a y leg increased the velocity in the remaining leg and there fore the resistance.