K coefecient of nozzles 1

[mechanicaldup]

Hi

do anyone know what is the K value of discharge nozzles of wash down lines and fire hose reels?

 

[JimCasey]

According to the Crane "Flow of fluids" book,
K2=(1-beta^2)*0.8* sin (theta/2)/(Beta^4)

Beta = area of outlet /Area of inlet
Theta is the cone angle as the nozzle reduces.

in my 1988 version of the book it is on page 52.

 

[mechanicaldup]

thks JimCasey

what velocity is used to detemine the pressure loss; inlet or outlet velocity?

 

[abeltio]

JimCasey,
Note that CRANE defines
beta = d1/d2
d1 = smaller diameter
d2 = larger diameter

beta is defined in page 2-11 Title: contraction and enlargement

mechanicaldup... in the Flow of Fluids Technical paper subindex 1 always refers to the smaller diameter and subindex 2 to the larger diameter...

so, K2 is referring to the larger diameter.
In case of a tapered contraction (your discharge nozzle), K2 refers then to the INLET (larger diameter).

the relationship between K1 and K2 is:
K2 = K1/beta^4





saludos.
a.