Problem 4.133
[Difficulty: 3]
CS
(moves
at speed U)
y
x
c
d
R
x
R
y
Given:
Water jet striking moving vane
Find:
Expressions for force and power; Show that maximum power is when U = V/3
Solution:
Basic equation: Momentum flux for inertial CV
Assumptions:
1) Steady flow
2) Incompressible flow 3) Atmospheric pressure in jet 4) Uniform flow
5) Jet relative velocity is constant
Then
R
x
u
1
ρ
−
V
1
⋅
A
1
⋅
()
⋅
u
2
ρ
V
2
⋅
A
2
⋅
⋅
+
=
VU
−
−
ρ
−
⋅
A
⋅
[]
⋅
−
(
) cos
θ
⋅
ρ
−
⋅
A
⋅
⋅
+
=
R
x
ρ
−
2
A
⋅
cos
θ
() 1
−
⋅
=
This is force on vane; Force exerted by vane is equal and opposite
F
x
ρ
−
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '07
 Lear
 Fluid Dynamics, Fluid Mechanics, Force, Special Relativity, Flux, Cos, Incompressible Flow

Click to edit the document details