Page 168 - Mechanical Engineer's Data Handbook

FLUID MECHANICS 157

4.4.4 Flow through annulus (small gap) Q
Mean velocity V=
z(R2 -r2)

0

Use formula for flat plates but with B = zD,, where D, 0
is the mean diameter.

Flow through annulus (exact formula)

?K (R2 -r2)
Flow Q =- (PI -p2) (R2 -r2) (R2 + r2)-- 1
8uL R
In -

4.5 Fluid jets

If the velocity or direction of a jet of fluid is changed, is proportional to the mass flow rate. Examples are of
there is a force on the device causing the change which jets striking both fixed and moving plates.

Change of momentum of aJIuid stream For flow in one direction, the force on a plate, etc.,
causing a velocity change is
Let :
m=mass flow rate=pAV F=h( VI - V2)
VI =initial velocity
Vz =final velocity 4.5. I Jet on stationary plates
p =fluid density
It1
A=flow area Jet on upat plate

I' il In this case V2 =0, and if VI = V
F=mV=
A II I

Flat plate, e = Boc
Angled plate, 8c90"