what is relation between air velocity(lit/s)and pressure

[soheil1979]

hi
is there any direct or indirect relation between air velocity(lit/s)and air pressure .if u know please help me and write its formula

 

[rb1957]

dynamic pressure = 1/2*rho*v^2

rho is air density = 0.002377 at sealevel
(the units are slugs/ft^3)
v is velocity in ft/sec
pressure is lbf/ft^2

 

[Feric]

Hi there:

One needs to use the Bernoulli equation.

Check out eFunda.com at:

http://www.efunda.com/formulae/fluids/bernoulli.cfm

Thanks,

Gordan

http://engware.i-dentity.com

 

[KENAT]

soheil, by lit/s you mean liters(litres) per second? This is volume flow rate not velocity. However, dividing it by the area it's flowing through will get you a velocity.

Looks like you're in SI so I'd convert the lit/s to m^3/s then go from there.

rb1957 equation is correct but in metric you'd use m/s for velocity, kg/m^3 and N/m^2 (or equivalent) for pressure.

Be aware, in a real world situation this will most likely only be an approximation.

KENAT, probably the least qualified checker you'll ever meet...

 

[rb1957]

and you've got to convert density to 1.225kg/m3 ...
but a good catch with OPs units.

and if we're in a duct, what's the pressure ?