start at edge
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I address this question especially (but not exclusively) to someone who has access to a small scale wind tunnel for aerodynamic testing, maybe even his (her) self built version in his (her) own basement or workshop.
An airfoil in a wind tunnel is usually depicted as in the image below:
… where we have a transparent tunnel (to be able to observe the smoke trails), an airfoil (wing) in the middle, a thin pipe for smoke injection through tiny nozzles (in this case 8 nozzles), with airflow from end “A” of the tunnel to end “B” of the tunnel.
This depiction is a generic one, but my question is about a more specific situation, where a second thin pipe is placed behind the airfoil (wing) and having not only the airflow direction (from A to B) but also the placement of the air pressure source (air pump / propeller / turbine …).
In scenario 1, the air pressure source is placed at end “A”, actually pushing (pressuring) the air into the tunnel, as seen in the image below:
In scenario 2, the air pressure source is placed at end “B”, actually sucking (vacuuming) the air out of the tunnel, as seen in the image below:
My question is:
How would the smoke trails (shape) after pipe nr. 2 look like in scenario 1 and how would they look like in scenario 2 ???
A reasonable assumption is that in both scenarios the smoke trails (shape) between end “A” and pipe nr. 1 would be the same, also between pipe nr.1 and pipe nr. 2.
Anyway, logic suggests that between pipe nr.2 and end “B”, the shape of smoke trails should be different, depending on the placement of the air pressure source (scenario 1 or scenario 2).
Any answer will be welcome and appreciated, thank you.
An airfoil in a wind tunnel is usually depicted as in the image below:
… where we have a transparent tunnel (to be able to observe the smoke trails), an airfoil (wing) in the middle, a thin pipe for smoke injection through tiny nozzles (in this case 8 nozzles), with airflow from end “A” of the tunnel to end “B” of the tunnel.
This depiction is a generic one, but my question is about a more specific situation, where a second thin pipe is placed behind the airfoil (wing) and having not only the airflow direction (from A to B) but also the placement of the air pressure source (air pump / propeller / turbine …).
In scenario 1, the air pressure source is placed at end “A”, actually pushing (pressuring) the air into the tunnel, as seen in the image below:
In scenario 2, the air pressure source is placed at end “B”, actually sucking (vacuuming) the air out of the tunnel, as seen in the image below:
My question is:
How would the smoke trails (shape) after pipe nr. 2 look like in scenario 1 and how would they look like in scenario 2 ???
A reasonable assumption is that in both scenarios the smoke trails (shape) between end “A” and pipe nr. 1 would be the same, also between pipe nr.1 and pipe nr. 2.
Anyway, logic suggests that between pipe nr.2 and end “B”, the shape of smoke trails should be different, depending on the placement of the air pressure source (scenario 1 or scenario 2).
Any answer will be welcome and appreciated, thank you.
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