Solution Naval Numerical 29
Numerical
29: A propeller 4.6m diameter has a pitch of 4.3m and boss diameter of
0.75. The real slip is 28% at 95 rev/min. Calculate the speed of
advance, thrust and thrust power.
Solution: Given diameter of propeller =4.6m
Pitch =4.3m
boss dia =0.75m
real slip =28%
RPM =95rev/min
to find Va, T and tp
Theoretical speed Vt=
Vt =
Vt=13.23knots
Real slip=
0.28=
Va=13.23(1-0.28)
Va=9.53knots
Estimated disc area A= "\small \frac{\pi}{4}x\left ( D^{2}-d^{2} \right )")
Put D=4.6 and d=0.75
=16.18m2
Thrust =
T =^{2} "\small 1.025 x16.18x0.28x4.3^{2}x\left ( \frac{95}{60} \right )^{2}")
T = 215.2kN
Thrust power = T x Va
=215.2 x 9.53 x 1852/3600
tp =1055 kW
Solution: Given diameter of propeller =4.6m
Pitch =4.3m
boss dia =0.75m
real slip =28%
RPM =95rev/min
to find Va, T and tp
Theoretical speed Vt=
Vt =
Vt=13.23knots
Real slip=
0.28=
Va=13.23(1-0.28)
Va=9.53knots
Estimated disc area A=
Put D=4.6 and d=0.75
=16.18m2
Thrust =
T =
T = 215.2kN
Thrust power = T x Va
=215.2 x 9.53 x 1852/3600
tp =1055 kW
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