Solve Airfoil Pressure at 1100m Altitude

[hallo]

Hi,

velocity of air=0, an airfoil or wing with is moving forwards with a velocity of 40m/s at an altitude of 1100m. At a certain point close to the wing (which is a point on top of the wing) ,the air speed relative to the wing is 50m/s.Find the pressure at that point.

Somebody pls help me...

I trz to use the formula of 1/2*(density)*(velocity)^2 + pressure + (density)*g*z which is bernoulli"s equation and is wrong...

thanx

 

[chaoseverlasting]

1/2d*40*40 +p1=1/2d*50*50 +p2. I think this should be it. Is this what you did?

 

[hallo]

yes,but how to get p1 and p2 ??

 

[Astronuc]

yes,but how to get p1 and p2 ??

Well with two unknowns, one would need to independent equations.

However, if p1 is taken as the pressure in air (i.e. far field or upstream of foil), then what is static air pressure at 1100m?

This might be of use -
http://www.grc.nasa.gov/WWW/K-12/airplane/dynpress.html

http://www.grc.nasa.gov/WWW/K-12/airplane/atmos.html

Intro to aerodynamics -
http://www.grc.nasa.gov/WWW/K-12/airplane/bga.html

 

[hallo]

static air pressure equals to 1.23 * 9.81 * 1100m . Am I rite?? but the answer is wrong if I use this value...

 

[Astronuc]

static air pressure equals to 1.23 * 9.81 * 1100m . Am I rite?? but the answer is wrong if I use this value...

Please provide the units!

It would appear that one is using $\rho{gh}$, and therefore one is finding the pressure at the bottom of a column of air of 1100 m height. Of course, one can subtract that value from 1 atm and obtain an reasonable approximation of the air pressure at 1100m above sea level.