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7/31/2019 Propeller Design Drawing PARTB
http://slidepdf.com/reader/full/propeller-design-drawing-partb 1/13
METHODICAL SERIES PROPELLER DESIGN PROCEDURE
1.
INPUT DATA(a) curve ( to include all allowances)V P E − E P
(b) S Rt w η η ,,, (Thrust identify assumed)
(c) ( de-rated to Continuous service rating)nP B , BP
(d) Propeller type, number of blades
(e) (101.327 ), (1.724 ), ρ ) AP 2 / mkn V p 2 / mkn
3 / 1025( mkg
(f) Immersion of propeller axis h.
2. DESIGN : OPTIMUM DIAMETER AND PITCH RATIO
S B DPP η .= V wV A )1( −=
525 Dn
Q
J
K openQ
ρ = =5
55
AV Dn 522
.
Dnn
P R D
ρ π
η
=5
55
AV Dn 5
2
2 A
R D
V Pnπρ
η
For two or more values of , carry out the calculations indicated in the following table:O E A A /
V AV 5
/ J K Q ( ) 4 / 15 / J K Q
J Oη H RO DP η η η
1 2 3 4 5 6 7
Columns 5 and 6 are obtained from the “optimum efficiency” line in the design chart.
Plot the curve andV P E − V P H RO D −η η η curves:
E P
E P
R H OOnnnP
for[ ]O E A A / 1
R H O D nnnP
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Determine the speeds for each at whichO E A A / H RO D E
PP η η η = , and by interpolation or
by adding another row for the speed determined from the plot, find and J Oη , and the
corresponding values of from the design chart. DP /
( )n J
V w
n J
V D A −
==1
Thus the optimum D and and the corresponding speed for each is determined. DP / O E
A A /
3. BLADE AREA
For the different values of carry out the calculations in the following table:O E A A /
Initial O E A A /
D
DP /
Oη
AV
From earlier calculations
RV 7.02 22
7.02 )7.0( DnV V
A R π +=
RV 7.025.0 ρ
2
7.0
7.05.0 R
V A R
V
gh pP
ρ
ρ σ
+−=
C τ from chart Burrill’s chart
T
A
H RO D
V
PT
η η η
=
P A
C R
PV
T A
τ ρ
1
5.02
7.0
⋅=
RequiredOE
A A / RequiredOE
A A /
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Plot AV DP D ,, / , 0η and requested to a base initial and determine all the
quantities for Required
O E A A / O E A A /
=O
E
A
AInitial
O
E
A
A
Initial AE /AO
VA
P/D
Reqd AE /AO
ηO
D
450
The propeller is designed:
Optimum DP D / ,
Required O E A A /
Speed attained have been determined.)1 /( wV V A −=
4. BLADE STRENGTH CALCULATIONS
Check for blade strength using classification society rules. Also determine shaft diameter etc.
5. PERFORMANCE ESTIMATION
By interpolation between the different standard values determine for the design
and the values of and
O E A A /
O E A A / DP / 2
/ J K T Oη for different values of : J
5
2
222
12
J
K J
J J
K
J
K Q
O
OQT η π
η π =⋅=
This involves filling up the following tables for each OE AA /
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After interpolation, plot and J Oη as a function of (it may be necessary to multiply
by 10 to get convenient numbers).
2 / J K r
2 / J K T
On
J
On
J
2 / J K T
322222222
22
422 )1)(1()1)(1(
1
V wt D
P
V wt D
V
P
V D
t
R
V
Dn
Dn
T
J
K E
E
A A
T
−−=
−−=−==
ρ ρ ρ ρ
Carry out the calculations in the following table:
V E P 2
/ J K T J Oη n
BP Col. Notes
1,2 From input data
3 From formula above
4,5 From plot above
6 ( ) D J
V wn
−=
1
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= 0.55 -0.2 for twin-screw ships.
Plot the results in the form of and V to a base of . On this superpose the engine BP n nP B −
curve (assuming ∝ ). BP n
)(Empirical Estimation for wake fraction
ω thrust deduction fraction (t).
Taylor’s
05.0− B5.0= C ω for single-screw ships
BC
Schoenherr’s
ω k t =7.05. to
for single screw ships
0k =
P
V
B
for streamlined rudder.
V
PB = k n (engine curve)
S H RO
E B
PP
η η η η =
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