1.
A survey vessel has a 10 ft diameter, B 590 propeller with a pitch of 10 ft.
The
propeller speed is 200 rpm, the boat speed is 20 knots, and the thrust reduction factor
(t) is 0.12, wake fraction (w) is 0.18, and the relative rotational efficiency
η
R
is 1.0.
The propeller operates as indicated by the Wageningen (Troost) Series B propeller
charts.
Determine:
a.
Thrust
b.
Shaft torque
c.
EHP of the boat
d.
The propeller shaft power (delivered power) P
D
e.
The (Quasi) PC or
η
D
The propeller is also tested at zero ship speed (bollard pull) and it is found that the
engine limits the torque to 50,000 lbf ft.
Determine:
f.
the propeller rpm and thrust at this condition
a. Prop. Thrust
.
p_over_d
p
d
:=
Given variables
V
s
20knot
:=
d1
0
f
t
:=
f
:=
p1
0
t
n_rpm
200
:=
ρ
1.9905lb
sec
2
ft
4
⋅
:=
η
R
1
:=
t.
1
2
:=
w.
1
8
:=
V
A
V
s
1w
−
()
⋅
:=
V
A
8.437
m
s
=
Velocity of Approach
J
1
V
A
nd
⋅
:=
n
n_rpm
60 sec
⋅
:=
n
3.333
1
s
=
Advance Ratio
J
1
0.83
=
Use the B 590 prop curve to determine K
T
and K
Q
K
T
.12
:=
K
Q
.023
:=
Thrust
K
T
ρ
⋅
n
2
⋅
d
4
⋅
:=
Thrust
2.654
10
4
×
lb
=
b. Shaft Torque
Torque
K
Q
ρ
⋅
n
2
⋅
d
5
⋅
:=
Torque
5.087
10
4
×
lb ft
⋅
=
PD
2
π
⋅
n
⋅
Torque
550
lb
ft
sec
⋅
hp
⋅
⋅
:=
c. Shaft powerr delivered
PD
1.937
10
3
×
hp
=
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 Fall '06
 DavidBurke
 Propeller, ft lb sec, lb ft sec

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