Air Velocity vs generated Pressure

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Discussion Overview

The discussion revolves around calculating the pressure exerted on a plate by wind blowing at a specific velocity. Participants explore the application of Bernoulli's equation and the relationship between pressure, force, and area in this context.

Discussion Character

  • Homework-related, Technical explanation, Conceptual clarification

Main Points Raised

  • Farid asks how to calculate the pressure on a plate from wind velocity, initially proposing a simple area for the plate.
  • Some participants suggest that the inquiry resembles a homework question and inquire about Farid's understanding of the problem.
  • Farid clarifies that the question is related to a work project and mentions using Bernoulli's equation to find dynamic pressure.
  • CS corrects Farid's initial misunderstanding about the relationship between force, pressure, and area, stating that force equals pressure times area.
  • Farid acknowledges the correction regarding the formula for force.

Areas of Agreement / Disagreement

Participants generally agree on the use of Bernoulli's equation for calculating pressure, but there is a correction regarding the relationship between force, pressure, and area that was initially misunderstood by Farid.

Contextual Notes

Farid's initial assumption about the area of the plate is noted as more complex than initially proposed, which may affect the calculations. The discussion does not resolve how to apply the equations to the actual area once determined.

Farid
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I have a simple question, can anyone please help. It goes something like this:
if wind is blowing at a velocity of 80 mph against a 2" X 2" plate, how much pressure (or force) is brought upon the plate?
would appreciate the formula, if any.
Thank you.


Farid
 
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Sounds like homework. Do you have any idea how you might find the answer?
 
Hi Russ,
No, it is not really homework. It is my project at work. However, the surface is area is more complex than I proposed above (2"x2"). Once I know, what method to use, then I can plug in the real "area".
I was going to find Pressure from the Bernoulie Eq. :
dynamic pressure = q= (roh*V^2)/2 or, q=.000256*V^2 [psf]
Once I know the pressure, then I can find the F=p/a, that my surface will be subjected to.
Right?


Farid
 
You are correct. A flat plate in a uniform airstream essentially converts all velocity pressure to static pressure via Bernoulli's eq.
 
Thank you.

Farid
 
Once I know the pressure, then I can find the F=p/a, that my surface will be subjected to.
Right?

NO, Force does not equal Pressure divided by Area. Force is equal to Pressure times Area.

P = F/A which gives F = P*A

CS
 

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