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Scale Effects on Ducted Propellers
Pages 744-759

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From page 744... ... That may be an explanation for often observed too light loaded propellers in fullscale which were designed on the basis of test results in model scale. INTRODUCTION In fact, long experience and well established methods are available for considering the scale effect on the characteristic of free running propellers, e.g. Read the entire page →
From page 745... ... Therefore many investigations have been carried out to study the effect of different boundary conditions, the size of the calculation domain and the topology of the numerical grid on the numerical results. NUMERICAL CALCULATION The calculation of the viscous flow on a ducted propeller is more complicated than that on a free running propeller. Read the entire page →
From page 746... ... The applied code is able to handle non-overlapping nonmatching grid interfaces. EXAMINATION OF THE BOUNDARY CONDITIONS turbulence models and/or dimensions of the calculation domain for the thrust loading coefficient CTh = 1 COO of the ducted propeller system are shown in Table 1. Read the entire page →
From page 747... ... The influence of the thrust loading coefficients on the propeller torque and thrust coefficients is limited in the range of 4.25 < CTh < 850. The- decrease of the propeller thrust and torque coefficients is effected by the increase of the flow velocity through the nozzle due to the higher efficiency of the nozzle at full-scale Reynolds numbers. Read the entire page →
From page 748... ... The Reynolds number effect on the characteristic of ducted propellers can be sumrnarised as follows: - high reduction of the propeller torque coefficient, reduction of the propeller thrust coefficient, increase of the nozzle thrust coefficient, nearly unchanged total thrust coefficient. Although the calculated results for full-scale agree with the observed tendencies in full-scale tests, more research work is needed to validate it. Read the entire page →
From page 749... ... thrust of the propeller Table 1: Influence of the applied boundary conditions on the . Test case Propeller thrust coefficient KTP Torque coefficient 10KQ Nozzle thrust coefficient ~ TV Totalthrust coefficient Ken Ratio KTP/KQ Ratio K~KQ Ratio KTN/KTP Thrust loading coefficient C77, Diameter of the grid Dca/c/D Location of inflow plane x/D . Read the entire page →
From page 750... ... OCFDcalculabon I E I polynomial coefficients 1 PSP Version 1.02 O CFD calculation propeller KA 5-75 Q polynorial coefficients PSP Version 1.02 propeller KA 4-70 DP 215-1345 J = 0.2242, C7N = 27, PID = 1.1867 10KQ KTN 10KQ DP 215-1345 J = 0.05, C7N = -420 (baCkWard) , P/D = 1.1867 Figure 3: Comparison of the coefficients for the ducted propeller DP 215-1345 (propeller KA 5-75, nozzle Wag. Read the entire page →
From page 751... ... i. .4 ., ~ ~ ~ :,,~, ^.~W I , ~ ~ ~ ~ //~, ,, ~ ~ hi' Figure 5: Velocity vectors on the nozzle leading edge, CTh = 4.25 8 Ds= 4.02 m Rn = 3.53X107 Read the entire page →
From page 752... ... 1~_ 1 1 � ~I j D5=2.01 m ~ ~ I ~ I l DS=4.02 m _~ Rn = l 25x107 ~ ~ ! � ~ Rn = 353x107 Figure 7: Velocity vectors on the propeller blade tip, CTh= 4.25 9 Read the entire page →
From page 753... ... ~ Z it, a N ,,, _ ~ I'- LIN ,. ~~,~w ~ <1 ~ ~ , ~~ ~~/ ', ~ Figure 9: Velocity vectors on the nozzle leading edge, CTh= 8.5 10 D5= 1.005 m Rn = 4.37x106 Ds=4.02 m R-= 3.50xlO' Read the entire page →
From page 754... ... . ___ _ _ ___._.__ _ _ Figure 11: Velocity vectors on the propeller blade hp. Read the entire page →
From page 755... ... ~ ~ l-~s:Ei01 ~ ~^~ ~ ~' ~,, _~_4_~[ I, ~ DM= 0.201 m ~, ! ', ff , / ~ Ds= 1.005 m ,~,xf'~/Ji' ' ~ I ~ ~ ~ ~ ~ \4~7~4~` 1 ~ t2i,3~-Q4~ ~ '' z ~^~N~,, ~-^;31iS}l ~ ~ s \| s , 1 ~ s ~ ~ R.,: Figure 13: Velocity vectors on the nozzle leading edge, CTh= 85 12 Read the entire page →
From page 756... ... ~ ~ DM= 0.201 m Rn = 3.87xlOs 4~ Figure 14 Velocity vectors on the nozzle trailing edge, CTh = 85 DS = 1.005 m Rn = 4~32X106 Figure 15: Velocity vectors on the propeller blade tip, CTh= 85 13 i Ds=4.02m I l Rn = 346x107 ~ _ I _ ~ ~ . Read the entire page →
From page 757... ... if; Rn=~' ~ Rn=3~-~ ~ <~' Figure 17: Velocity vectors on the nozzle leading edge, CTh= 850 14 Read the entire page →
From page 758... ... ! 1 Ds=leoo5m _ ~ R ~ = 4.31~106 l Figure 19: Velocity vectors on the propeller blade tip, CTh= 850 15 i_ ~ _ _ ~ _ t . Read the entire page →
From page 759... ... 1~1~ Propeller torque coefficients DP 215-1345 r1 100 1000 � 1 1 1 1 Nozzle thrust coefficients DP 215-1345 1 ~ 1000 Nozzle thrust coefficients DP 215-1345 10 Ds/D`~r -- ~ ] Read the entire page →

From page 744...

... That may be an explanation for often observed too light loaded propellers in fullscale which were designed on the basis of test results in model scale. INTRODUCTION In fact, long experience and well established methods are available for considering the scale effect on the characteristic of free running propellers, e.g.

Scale Effects on Ducted Propellers Pages 744-759

Scale Effects on Ducted Propellers
Pages 744-759