Densities & volumes
Join Date: Feb 2007
Location: Bournemouth
Age: 77
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OK Pigdog.
You have rumbled me as a "stirrer".
I just like to see what happens with spoofs.
I watch the "parrots" bit with interest and will submit the answer when there have been more replies.
In the meantime, here's another:
The equation of continuity and Bernoullis' Theorem tell us that in incompressible fluid flow an increase in velocity results in a decrease in pressure and vice versa.
Consider a windsock where the entrance is of larger area than the exit.
This represents a convergent duct. In a convergent duct (such as the first part of a carburettor venturi) there is an increase in velocity and a drop in pressure.
Question:
Why therefore does the windsock not collapse.....?
JP
You have rumbled me as a "stirrer".
I just like to see what happens with spoofs.
I watch the "parrots" bit with interest and will submit the answer when there have been more replies.
In the meantime, here's another:
The equation of continuity and Bernoullis' Theorem tell us that in incompressible fluid flow an increase in velocity results in a decrease in pressure and vice versa.
Consider a windsock where the entrance is of larger area than the exit.
This represents a convergent duct. In a convergent duct (such as the first part of a carburettor venturi) there is an increase in velocity and a drop in pressure.
Question:
Why therefore does the windsock not collapse.....?
JP
Join Date: Apr 2005
Location: Ireland
Age: 43
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Ok, I'll have a go, but I'm not 100% sure.
I would guess that the dynamic pressure of the wind hitting the inside of the sock is greater than the drop in static pressure.
Like when an aircraft flies upside down. The increase in pressure would still be produced on the underside of the wing, and the decrease would be on the topside. The only way level flight can be maintained is with a greater angle of attack. (By this I mean the pilot would push the control column forward.) The greater AoA uses dynamic pressure to produce lift.
Does that pass your test Mr. Jaguar? As I said, I'm not 100% sure, but...
I would guess that the dynamic pressure of the wind hitting the inside of the sock is greater than the drop in static pressure.
Like when an aircraft flies upside down. The increase in pressure would still be produced on the underside of the wing, and the decrease would be on the topside. The only way level flight can be maintained is with a greater angle of attack. (By this I mean the pilot would push the control column forward.) The greater AoA uses dynamic pressure to produce lift.
Does that pass your test Mr. Jaguar? As I said, I'm not 100% sure, but...
Join Date: Feb 2007
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Not a bad effort Pigdog.
Most people are wrong-footed by the word "venturi".
A venturi can only be formed by a tube with rigid construction.
A windsock is not rigid and therefore the pressure inside is higher than the static outside, so it is inflated.
JP
Most people are wrong-footed by the word "venturi".
A venturi can only be formed by a tube with rigid construction.
A windsock is not rigid and therefore the pressure inside is higher than the static outside, so it is inflated.
JP
Join Date: Apr 2005
Location: Ireland
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I see you're an ATPL lecturer. You must really enjoy your job since you're happy to teach on bank holidays.
Good for you.
Forgive me if I'm a little bit happy with myself... I haven't even started my ATPLs yet, and probably won't for another six months.
Our paths may yet cross on this holiest of Forums.
Good for you.Forgive me if I'm a little bit happy with myself... I haven't even started my ATPLs yet, and probably won't for another six months.
Our paths may yet cross on this holiest of Forums.
Join Date: Feb 2007
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Pigdog:
I do not teach on bank holidays - I just sometimes get bored.
I have in the past also worked for the CAA on the question database.
Our paths will undoubtedly cross again on this forum, and if you go to the right school they will cross in a classroom.
By the way, my specialist subject is Principles of Flight, but at RAF Central Flying School it was more aerodynamics. The two subjects are not the same.
Best of luck with your studies - it's a worthy profession.
JP
I do not teach on bank holidays - I just sometimes get bored.
I have in the past also worked for the CAA on the question database.
Our paths will undoubtedly cross again on this forum, and if you go to the right school they will cross in a classroom.
By the way, my specialist subject is Principles of Flight, but at RAF Central Flying School it was more aerodynamics. The two subjects are not the same.
Best of luck with your studies - it's a worthy profession.
JP
