AU593670B2 - A screw propeller boss cap with fins - Google Patents
A screw propeller boss cap with fins Download PDFInfo
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- AU593670B2 AU593670B2 AU76301/87A AU7630187A AU593670B2 AU 593670 B2 AU593670 B2 AU 593670B2 AU 76301/87 A AU76301/87 A AU 76301/87A AU 7630187 A AU7630187 A AU 7630187A AU 593670 B2 AU593670 B2 AU 593670B2
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- Australia
- Prior art keywords
- propeller
- fins
- cap
- boss
- fin
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H1/00—Propulsive elements directly acting on water
- B63H1/02—Propulsive elements directly acting on water of rotary type
- B63H1/12—Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction
- B63H1/14—Propellers
- B63H1/28—Other means for improving propeller efficiency
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H1/00—Propulsive elements directly acting on water
- B63H1/02—Propulsive elements directly acting on water of rotary type
- B63H1/12—Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction
- B63H1/14—Propellers
- B63H1/28—Other means for improving propeller efficiency
- B63H2001/283—Propeller hub caps with fins having a pitch different from pitch of propeller blades, or a helix hand opposed to the propellers' helix hand
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- Mixers Of The Rotary Stirring Type (AREA)
Description
r 1 FORM 10 593670 SPRUSON FE GUSON COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION
(ORIGINAL)
FOR OFFICE USE: Class Int, Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: Name and Address of Applicant: I 1 t i II o I t I 1 t ti Address for Service:
II
Mitsui O. S. K. Lines, Ltd.
6-32, Nakanoshima 3-chome Kita-Ku Osaka
JAPAN
West Japan Fluid Engineering Laboratory Co., Ltd.
283, Tanagato-cho Sasebo-City Nagasaki-Prefecture
JAPAN
Mikado Propeller. Co., Ltd.
1300-2, Aza Kuchi-irino Yabata, Nabari-City Mie-Prefecture
JAPAN
Spruson Ferguson, Patent Attorneys, Level 33 St Martins Tower, 31 Market Street, Sydney, New South Wales, 2000, Australia i.
i ?1 Complete Specification for the invention entitled: A Screw Propeller Boss Cap With Fins The following statement is a full description of this invention, including the best method of performing it known to me/us -2 BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a boss cap of a screw propeller, particularly to a screw propeller boss cap with fins.
Description of the prior art In order to improve the characteristics of a screw o propeller, particularly the propeller efficiency, extensive o and intensive researches have already been made by engineers So'O with respect to the technical design of number, shape, 06 developed area, pitch, etc. of blades and now their fruits materially have been brought forth to a nearly maximum extent. Thus it is extremely difficult to expect any future drastic improvement of the propeller characteristics through researches on these items.
4i On the other hand, it has been known that the propeller efficiency of a screw propeller is low in the proximity of its boss. For this reason, it has been proposed for several times to provide a small diameter So propeller at the rear stream side of the main propeller so that the propeller efficiency in the proximity of its boss
I
I
_I
00 0 o 0O 0 9 4,, 4 -3may be raised, for example, in the Japanese Utility Model Laid-opens Nos. 30,195/81 and 139,500/82. It seems however that such idea in fact was not successful, probably for the reason that the thrust does not so much increase as the torque increases and thus the propeller efficiency is not so improved as expected.
SUMMARY OF THE INVENTION An object of the present invention therefore is to provide a new technique which enables to improve the propeller characteristics particularly the propeller efficiency to a considerably high extent through addition of a boss cap with fins to a propeller.
As shown in the attached drawing of Fig. 3 (prior art technique), an ordinary screw propeller 31 comprises a plurality of blades 33 provided in a equidistance around the periphery of a boss 32 and is connected through the boss 32 to a rotational drive shaft 34. On an end opposite to the drive shaft 34 of the boss 32, a conical boss cap 35 is mounted in order to reduce vortices generated downstream of the boss 32 as much as possible.
The present inventors have focused their attention on the fact that even in the rear stream of such propeller ~~rcl- -4boss cop, a considerably hub vortex 36 Is generated and, in the thought that the prior art small diameter additional propeller would have Increased such hub vortex, have made Intensive researches seeking to find any other means for reducing such hub vortex. Finally It has been found that the addition of a boss cap with fins to a propeller can reduce such hub vortex and in effect can increase the propeller efficiency.
In one broad form the present invention provides a cap for mounting on a boss of a screw propeller, said propeller having at least one propeller blade extending radially outwards from said boss with the propeller blade root having a geometric pitch angle "epsalon"; wherein said cap comprises: at least one fin for e?"h propeller blade; said fin or fins having an Inclination "alpha" whereby the angular difference between the pitch angle "epsalon" and the fin Inclination "alpha" being in the range -200 to wherein the leading edge of each fin is located between adjacent propeller blade roots; e* .and wherein the fins have a maximum diameter which is larger than the diameter of an end portion of the boss to which the cap is to be 20 mounted, and not larger than 33% of the maximum diameter of the propellers.
The fins provided according to the present invention are not necessarily for generating a thrust by themselves, but for generally guiding the water stream rearward of the boss cap to a direction to reduce the generation of the hub vortex.
Owing to such guide effect, the hub vortex in the rearward of the boss cap can be diffused whereby the drag force induced by the vortex on a propeller blade plane is reduced and as a result the propeller characteristics, and particularly the propeller efficiency, may be greatly improved without a substantial increase in the required torque.
Accordingly, the present invention may give a particularly beneficial effect to a propeller having a higher pitch ratio which generates a stronger hub vortex. As shown in the preferred embodiments of the present invention hereinafter, the fins may have a rake angle or a positive or negative camber against the boss cap.
Preferred forms of the present invention will now be described by way f example with reference to the accompanying drawings, wherein: S/L Fig. 1 is a front view of a propeller on which an
I
r s ix.l i i d i ii ,0o 00 0 *0 0 000 *0I 0 0 4t~ embodiment of the propeller boss cap with fins of the present invention is mounted, and Fig. 2 is a side view of the Fig. 1.
Fig. 3 is a side view similar to the Fig. 2, but shows a propeller and a boss cap of prior art technique without fins together with a hub vortex generated rearward of the boss cap.
Fig. 4 is a side view partly shown in the section of a propeller characteristics measurement apparatus used in the experiments.
Fig. 5 is a plan view showing plane shape of the fins used in the experiments and Fig. 6 is a side view showing the mounting positions of the fins to the propeller boss cap.
Fig. 7 shows the propeller characteristics curves obtained in the Experiment No. 1 and Figs. 8-10 show the schematic illustrations representative of the relative positions of the propeller blades roots and the fins in the Experiments Nos. 2-4, respectively.
Fig. 11 Is a side view to show the rake angle of the fins in the Experiment No. 5 and Fig. 12 is an A-A line i i lit a.
j sectional view of the Fig. 11.
Fig. 13 is a schematic illustration similar to the Figs. 8-10, but showing the relative positions of the propeller blades roots and the fins in the Experiment No. 6.
Fig. 14 is a diagram showing the results of the Experiment No. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be 0a So* explained in detail with reference to the attached drawings.
i oto Tests are made in a water tank, using models of propellers having the data as shown in the following table 1. The water tank is of a circular stream type and has an observational part of scales 5.0 m (length) X 2.0 m (width) Y, m (depth). The maximum flow rate is 2.0 m/sec and the uniformity of the flow rate is within Table 1 Type CP24 CP26 Diameter (mm) 220.0 220.0 Pitch ratio 0.8 1.2 U3 r4-~ 7 Developed blade area ratio Boss ratio Blade thikness ratio Blade cross section shape Blade number 0.55 0.18 0.05
MAU
4 0.55 0.18 0.05
MAU
4 o o o 04 4 4 In Fig. 4, a side view of a propeller characteristics measurement apparatus is shown partly by a section. This apparatus is located in the observational part of said water tank by securing its propeller open boat 41 to a rigid carrier (not shown) placed above the water tank. The boat 41 has a drive mechanism 43 to rotate a propeller 42 which may detachably be attached to its tip end, a thrust detector 44 and a torque detector
I.
Although not shown in the Fig. 4, a propeller rotating speed is measured by a digital counter TM-225 (product of Ono Measurement Instruments company, Japan) and a flow rate by a combination of a JIS type Pitot tube and a differential pressure converter DLPU-0.02 (product of Toyo Boldwin company, Japan). The analogue signals of such Qo thrust, torque and flow rate represented by the differential pressure, etc. are converted to digital signals through an A/D converter provided in a microprocessor located in a separate controller and processed into physical data which AL,, then are printed by a pinter or plotted by a plotter. r i r i
IV
A thrust coefficient (KT) and a torque coefficient (KQ) are measured under different advance coefficients (J) adjusted by changing the flow rate while keeping the propeller rotating speed approprimately constant within the range of 7.5-9.0 The depth in water of the propeller center is 300 mm and the direction of water flow is as shown by an arrow in the Fig. 4.
As a boss cap to be mounted on the propeller models, a cap of a rounded conical shape having a base diameter of 35 mm and a height of 25.6 mm is prepared. The ooe cap may be mounted on the propeller by any known means and 0 0* in these experiments a bolt-nut securing is employed.
oa 4 SAs fins to be provided on the boss cap, those having six different triangular shapes shown by a plan view in Fig. 5 are prepared from flat plates of 1 mm thickness to have the dimensions as shown in the following table 2.
I Table 2 Fin shape Width Height o (X-axis direction) (Y-axis direction) 20 mm 20 mm 26 mm 16.5 mm
A'
m
'V-
B J3 r i~l 26 mm 21 mm 26 mm 28.5 mm 26 mm 34 mm 26 mm 39.5 mm Fig. 6 shows the relative positions of the fins and the boss cap. In this Fig. 6, a rear end 0 of a root 62 of a propeller blade 61 is set on the propeller axis 63 as a reference point. In this specification, a peripheral distance from the front end of a fin 64 to the plane tO including the reference point O and the propeller axis 63 is called (positive in the direction of propeller rotation S shown by an arrow). A surface distance from the front end at., of the fin 64 to a periphery including the reference point O is called The angle of the fin 64 against plane normal to the propeller axis is called "Alpha". The geometric pitch angle of the propeller blade root 62 is called "Epsilon".
In this specification, the geometric pitch angle "Epsilon" of a propeller blade root is one based upon a i o nose-tail line of the propeller blade root. More precisely, two surfaces of a cylindrical surface having an axis on the propeller axis and a radius equal to the boss radius and a propeller blade surface or its extension as a suspected surface are considered. A cylindrical surface intercepted
CO
N~
Fi \o, i by a crossing line between these two surfaces, that is, a cylindrical section, is developed on a plane. In the developed view, an angle between a nose-tail line of the blade section defined by the developed cylindrical section and a line normal to a generatrix of the cylindrical surface corresponds to the "Epsilon".
The fin 64 is mounted on the boss cap in the direction perpendicular to the sheet of the Fig. 6, when no rake angle is given. The mounting is made, in these O experiments, by cutting a groove on the boss cap, inserting the lower portion of the fin into the groove and fixing by means of an adhesive, but it is of course possible and in actual cases it is preferred to form the boss cap and the fins integrally as one body. The broken lines shown in the lower portions of fins in the Fig. 5 indicate crossing lines between the fin surface and the boss cap surface after mounting of the former on the latter.
Experiment 1 Water tank tests have been made by using the ao propeller of the type CP26 (Epsilon=67.4 0 and the fins of Fig. The fins of total number 4, one for each ~ALILq propeller blade, are mounted on the boss cap in positions of mm, b=5 mm and Alpha=66 0 In this instance, the maximum diameter of the fins, that is, a doubled distance (2r) between the radially remotest end of a fin (from the propeller axis) and the propeller axis (after mounting of the fins on the boss cap) and a propeller diameter (2R) stand in a ratio r/R=0.23. Fig. 1 shows a front view of thus composed propeller 1, boss 2, propeller blades 3, shaft 4, boss cap 5 and fins 6; and Fig. 2 shows a side view (0 thereof. For comparison, tests have been made also as to cases without fins. The thrust coefficient (KT) and the torque coefficient (KQ) have been measured under various advance cuefficients of 0.0-1.1 and the propeller efficiency (Eta= J'KT/2PiKQ) has been calculated. Then an increase ratio (dEta) of the propeller efficiency increased from the cases without fins to the cases with fins has been calculated by percents. The results are shown in the following tables 3 and 4.
CV I 1 *nt i Y-l )1II. Table 3 (cases without fins) (0 090040
S
It No.
0 1 2 3 4 6 7 8 9 10 11 12 13 14 16 17 18 19 20 21 22
J
0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 1.000 1.050 1.100
KT
0.4816 0.4715 0.4606 0.4489 0.4363 0.4230 0.4088 0.3940 0.3785 0.3623 0.3454 0.3281 0.3102 0.2919 0.2731 0.2541 0.2349 0.2154 0.1959 0.1764 0.1570 0.1378 0.1189 KQ x 10 0.9376 0.9092 0.8823 0.8565 0.8316 0.8071 0.7829 0.7586 0.7342 0.7094 0.6839 0.6578 0.6309 0.6031 0.5743 0.5445 0.5138 0.4820 0.4494 0.4159 0.3817 0.3468 0.3115 Eta 0.0000 0.0413 0.0831 0.1251 0.1670 0.2085 0.2493 0.2893 0.3282 0.3657 0.4019 0.4365 0.4695 0.5007 0.5299 0.5571 0.5820 0.6046 0.6244 0.6413 0.6547 0.6639 0.6680 0bttr
I
Bt
S(
Table 4 (cases with fins) No.
0 1 2 3 4 6 7 8 9 11 12 13 14 16 17 18 19 21 22
J
0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 1.000 1.050 1.100
KT
0.4985 0.4894 0.4785 0.4660 0.4522 0.4373 0.4215 0.4050 0.3880 0.3705 0.3528 0.3349 0.3168 0.2986 0.2803 0.2617 0.2430 0.2239 0.2044 0.1843 0.1634 0.1417 0.1187 KQ x 10 0.9154 0.8914 0.8677 0.8440 0.8204 0.7965 0.7724 0.7479 0.7229 0.6973 0.6710 0.6441 0.6164 0.5879 0.5585 0.5284 0.4974 0.4655 0.4328 0.3994 0.3652 0.3303 0.2947 Eta 0.0000 0.0437 0.0878 0.1318 0.1755 0.2184 0.2605 0.3016 0.3417 0.3806 0.4184 0.4552 0.4909 0.5255 0.5590 0.5913 0.6220 0.6506 0.6762 0.6976 0.7123 0.7168 0.7053 dEta(%) 5.55 5.35 5.09 4.81 4.54 4.29 4.09 3.96 3.90 3.95 4.09 4.35 4.73 5.21 5.78 6.42 7.07 7.66 8.07 8.09 7.38 5.29
SQ
SQ
Sr S IS 1 F' ~C_*Ef_ "I "urr~ /eL Fig. 7 illustrates the results of the tables 3 and 4 showing the advance coefficient in abscissa and the thrust coefficient the torque coefficient multiplied by ten (KQ x 10) and the propeller efficiency (Eta) in ordinate. In this Fig. 7, curves T2, Q2 and P2 represents KT, KQ x 10 and Eta in the table 3 and curves T3, Q3 and P3 represents KT, KQ x 10 and Eta in the table 4. From this Fig. 7 and the table 4, it is understood that the propeller efficiency increases about 4-8% in the overall range of (o J=0.05-1.10 and particularly 7.66% at the usually employed J=0.9.
Further, in these tests, a needle pipe is manually put into the water from above the water tank to the close proximity of the rear end of the boss cap to supply air bubbles. I L has been found that in the cases without fins, a large number of air bubbles align along the propeller axis, but in the cases with fins, air bubbles are diffused to disappear. It is considered that a hub vortex is greatly reduced by the merit of the fins.
Sreduced by the merit of the fins.
0 00 0 *r or eM 0I 9 0 1 r~ r ao Experiment 2 441' Tests similar to those shown in the Experiment 1 have been made, but using different positions of fins, that is, different a, h and Alpha. The propeller efficiency 4 increase ratio obtained under the usually employed advance coefficient is shown in the following table Table No. a b Alpha Alpha- r/R dEta (mm) (mm) Epsilon( 0 1 10 0 64 -3.4 0.25 5.49 2 15 0 61 -6.4 0.25 7.32 3* 10 5 66 -1.4 0.23 7.66 4 14 5 59 -8.4 0.23 6.39 from the data in the Experiment 1 The relative positions of fins and the propeller blade roots are illustrated in Fig. 8, wherein the rear end 0 of one propeller blade root shown in the Fig. 6 is placed on the base line X, and the blade position is shown as a line segment starting from the base line X with an angle Epsilon and having a length corresponding to the length of the nose-tail line of the propeller blade root. Another propeller blade root adjacent to said one also is shown is a similar manner, but at a peripheral distance between the ;ao rear ends of them taken in the, direction of the base line X.
The positions of the fins are shown by taking of the Fig. 6 in the direction of the base line X and of the ~ALq -1l at i i r v /4 rt- Fig. 6 in the direction of a base line Y which passes through the reference point 0 normally to the base line X.
The lengths of the fin segments correspond to the lengths of the crossing lines between the fins and the boss cap as shown in the Fig. 5 by broken lines. From the table 5 and the Fig. 8, it is understood that a considerable improvement of propeller efficiency can be obtained when the front ends of fins are placed between the adjacent propeller blade roots, that is, within a space between extended nose-tail (O lines of the adjacent propeller blade roots.
oa|.,e Experiment 3 o *9 0* Tests similar to those of Experiment 1 have been 4 0 S made, but changing only Alpha. The propeller efficiency increase ratio obtained at the advance coefficient (J)=0.9 is shown in the following table 6.
i i 4*4 Table 6 t No. Alpha(°) Alpha-Epsilon(') r/R dEta(%) 1 45 -22.4 0.24 0.34 2 50 -17.4 0.235 3.46 t, 3* 66 1.4 0.23 7.66 4 85 17.6 0.22 3.80 90 22.6 0.22 2.19 L I 1/4 a, ~t 17 a. 100 105 27.6 32.6 37.6 0.22 0.22 0.22 2.38 0.77 0.47 9 A p ~t t4 4 from the data of Experiment 1 The results of the table 6 are shown in Fig. 9 similarly to the Experiment 2. It is understood from the table 6 and the Fig. 9 that a considerable improvement of propeller efficiency can be obtained within the range of -200 Alpha-Epsilon s 300 Experiment 4 Tests similar to those of Experiment 2 have been made, but using the propeller of the type CP24 (Epsilon=57.4°) and the fins of the Fig. 5(A) and The propeller efficiency increase ratio obtained at the advance coefficient usually employed for such propeller is shown in the following table 7.
Table 7 'i: t No. a (mm) 1 0 b (mm) 5 Alpha (0) 80 Alpha- Epsilon() 22.6 r/R Fin shape dEta 2.03 0.21 I F-zK 2 10 17 63 5.6 0.18 3.02 3 5 12 63 5.6 0.20 2.06 4' 5 9.5 63 5.6 0.21 2.32 5 7 63 5.6 0.215 2.84 6 10 7 63 5.6 0.23 3.93 7 10 7 57 -0.4 0.22 2.32 8 6 7 63 5.6 0.22 2.57 9 4 5 35 -22.4 0.235 -0.09 4 5 90 32.6 0.22 -0.19 to The results of the table 7 are shown in Fig. similarly to Experiment 2. It is understood that there is no material difference between the fin shapes and (C) and that the fin positions should satisfy the conditions that the front end of the fin is located between the adjacent propeller blade roots and the inclination of the fin stands within the range of -20 0 °Alpha-Epsilon S 30° as in the case of said Fig. 9.
Experiment The test of Experiment 4, No. 6 has been repeated, a 0 adding rake angles of +300 to the fins. The rake angles are i S measured from the direction perpendicular to the sheet of the Fig. 6 to the direction of rotation of the propeller.
The results are shown in the following table 8.
I r Table 8 No.* a (mm) 6F 10 6M* 10 6B 10 b (mm) 7 7 7 Alpha (6) 63 63 Alpha- Epsilon(I) 5.6 5.6 5.6 r/R Rake Angle (0) 0.21 +30 0.23 0 0.21 -30 dEt a
M%
1.46 3.93 4.47 0 0 0 0
I
t .from the data of Experiment 4 From the table 8, it is understood that there is a tendency of further improvement of dEta when a rake angle opposite to the rotation direction of the propeller is added to fins. The mounting positions of fins are shown in Fig. 11 by way of a side view similar to the Fig. 6 and in Fig. 12 4 1 which is an A-A line section of the Fig. 11.
Experiment 6 The tests of Experiment 4, No. 7 has been repeated, but by changing the number and positions of the fins, the results are shown in the following table 9.
t I 4 _i i -24-- Table 9 No. a b Alpha Alpha- r/R Fin dEta (mm) (mm) Epsilon(O) Number 7-N2 10** 7 57 -0.4 0.22 2 -0.12 7-N3 10** 7 57 -0.4 0.22 3 0.49 7-N4* 10 7 57 -0.4 0.22 4 2.32 10** 7 57 -0.4 0.22 5 -1.12 .from the data of Experiment 4 value of one specific fin; values of the (o other fins correspond to the positions o o determined by the quotient of 3600 divided by the number of fins a 0 C a The relative positions of the propeller blade roots and the fins are shown in Fig. 13 by way of X-Y plane as in the Figs. 8-10. Relative to the four propeller blade
I
roots Bl-B4, the fins are located, in the case of fin number Str two, at the positions 1/F and 2/2; in the case of fin number three, at the positions 1/F, 2/3 and 3/3; in.the case of fin number four, at the positions 1/F, 2/4, 3/4 and 4/4; and in a o the case of fin number five, at the positions 1/F, 2/5, 3/5, 4/5 and 5/5, as shown in the Fig. 13. It.can be seen therefrom that there is no fin located, in the case of fin number two, between the propeller blade roots B2 and B3 and j
-I
r :9 ~n~bc tb between B4 and Bl; in the case of fin number three, between B3 and B4. Further, there are two fins between B3 and B4 in the case of fin number five. Thus the fins are not evenly positioned in the cases of fin number two, three and five.
It is understood from the table 8 that the number of fins should be same for each space between the adjacent propeller blade roots.
Experiment 7 Tests similar to those of Experiment 1 have been made, but by using various fins of the Fig. having the same width but different heights. Total four same shape fins, one for each propeller blade, are mounted in the positions determined by a=10 mm, b=5 mm and Alpha=66 The propeller efficiency increase ratio obtained at the advance coefficient is shown in the following table 0 *o 0 9, *o 00 '4, k 1 ttI ~r
L
"I
No.
tct(~ a (mm) b (mm) 5 5 5 i Alpha (0) 66 66 66 Table Alpha- Epsilon( -1.4 -1.4 -1.4 r/R Fin shape 0.2 (B) 0.23
(C)
0.3 In dEta 4.12 7.66 6.08
I:
1 r -2 23r.-C-P b-f 4 10 5 66 -1.4 0.35 0.87 10 5 66 -1.4 0.4 -0.50 from the data of Experiment 1 The results of the table 10 are illustrated in Fig. 14, taking r/R in abscissa and dEta in ordinate.
In view of the fact that the boss ratio of the propeller of type CP26 is 0.18, it is unerstood that the maximum diameter of the fins should be greater than the diameter of the cap-mounting end of the boss and not be greater than 33% of the propeller diameter, in order to i obtain a considerable improvement of the propeller Sefficiency.
fit Experiment 8 Tests similar to those of Experiment 1 have been made, but by using fins of the Fig. 5(C) bended to an arc of radius 50 mm. Two kinds of fins, one bended to the arc convex in the direction of propeller rotation C-out) and the other to the arc concave in the direction of propeller rotation C-in), are used. Total four same shape fins, ao one for each propeller blade, are mounted in the positions determined by a=10 mm, b=5 mm and Alpha=66 0 angle of the I 01 L\ .4 l 1 l W 4 riirmri'^,*.)^^ c 34= direction of the chord of the arc). The propeller efficiency increase ratio as obtained at the advance coefficient is shown in the following table 11.
No. a (mm) 10 b (mm) 5 5 5 Alpha (0) 66 66 66 Table 11 Alpha- Epsilon(") -1.4 -1.4 -1.4 r/R Fin shape 0.23 0.23 0.23 C-out
C
C-in dEta 6.46 7.66 6.94 1- I;r t t I I (If S. from the data of Experiment 1 shape of positive From the above data, it is understood that the fins is not limited to plane and may have a or a negative camber.
1 As explained in detail above, it is possible to improve the propeller characteristics particularly the propeller efficiency without increasing torque, by the effect of guiding the water stream rearward of the boss cap to a direction of reducing generation of hub vortex, through the provision of fins on a boss cap to be mounted on a screw propeller in accordance with the present invention.
-CZ I tI i:'1"fri According to such invention, further merits are obtained, for example, the propeller characteristics may greatly be improved only by a slight modification of a rather small boss cap and not by a drastic change of the screw propeller itself, to which the boss cap is appended, necessitating difficult work and high cost. In effect, the present invention is appli.cable to screw propellers already mounted on existing ships, simpl~y by exchanging or working the boss cap without incurring high cost.
'*f 'a 44 4 444 4 44 4g. 4 94 4* 44 4 44
Claims (5)
1. A cap for mountiing on a boss of a screw propeller, said propeller having at least one propeller blade extending radially outwards from said boss with the propeller blade root having a geometric pitch angle "epsalon"; wherein said cap comprises: at least one fin for each propeller blade; said fin or fins having an inclination "alpha" whereby the angular difference between the pitch angle "epsalon" and the fin inclination "alpha" being in the range -20° to wherein the leading edge of each fin is located between adjacent propeller blade roots; and wherein the fins have a maximum diameter which is larger than the diameter of an end portion of the boss to which the cap is to be mounted, and not larger than 33% of the maximum diameter of the propellers.
2. A screw propeller having at :east one propeller blade extending radially outwards from a boss and comprisiig the cap defined in claim 1.
3. The propeller of claim 2 wherein the cap is positioned upstream of said propeller blades.
4. The propeller of claim 2 wherein said cap is located downstream of said propeller blade. A
5. A cap for a screw propeller boss as hereinbefore described with reference to, and as shown in the accompanying drawings. 0000 o t t 0 6 00 0 0 a f0 0 G 0 DATED this SIXTEENTH day of NOVEMBER 1989 Mitsui 0 S K Lines Et Al l "Patent Attorneys for the Applicant ^SPRUSON FERGUSON C r r I' L q i- L L
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP61-181577 | 1986-07-31 | ||
JP18157786 | 1986-07-31 | ||
JP18889886 | 1986-08-11 | ||
JP61-188898 | 1986-08-11 |
Publications (2)
Publication Number | Publication Date |
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AU7630187A AU7630187A (en) | 1988-02-04 |
AU593670B2 true AU593670B2 (en) | 1990-02-15 |
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ID=26500707
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU76301/87A Expired AU593670B2 (en) | 1986-07-31 | 1987-07-30 | A screw propeller boss cap with fins |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP0255136A1 (en) |
AU (1) | AU593670B2 (en) |
CA (1) | CA1289821C (en) |
FR (1) | FR2619352A1 (en) |
GB (1) | GB2194295B (en) |
HK (1) | HK85092A (en) |
SG (1) | SG60592G (en) |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA1289821C (en) * | 1986-07-31 | 1991-10-01 | Michihito Ogura | Screw propeller boss cap with fins |
JP2947357B2 (en) * | 1989-08-18 | 1999-09-13 | 日産自動車株式会社 | Propeller structure of high-speed boat |
US5096383A (en) * | 1989-11-02 | 1992-03-17 | Deutsche Forschungsanstalt Fur Luft- Und Raumfahrt E.V. | Propeller blades |
EP0758606A1 (en) * | 1995-08-16 | 1997-02-19 | Schottel-Werft Josef Becker GmbH & Co KG. | Hub cap for ship propellers |
DE10152977C1 (en) * | 2001-10-26 | 2003-05-08 | Howaldtswerke Deutsche Werft | Device for counteracting flow vortices generated in the hub area of propellers and / or propeller drives in the surrounding fluid |
FI115210B (en) | 2002-12-20 | 2005-03-31 | Abb Oy | Device in a propulsion system |
CN103097238B (en) * | 2010-07-12 | 2016-09-21 | 罗尔斯-罗伊斯股份公司 | There is the marine ship of propulsion unit |
DE102011055515A1 (en) | 2011-11-18 | 2013-05-23 | Becker Marine Systems Gmbh & Co. Kg | Propeller arrangement, in particular for watercraft |
CN103115021B (en) * | 2013-02-01 | 2015-03-04 | 华中科技大学 | Vane wheel device |
SG10201810020RA (en) * | 2014-05-28 | 2018-12-28 | Korea Inst Ocean Sci & Tech | Combined propeller cap for reducing rotating flow and hub vortex and enhancing propulsive efficiency |
JP6812057B2 (en) * | 2017-06-21 | 2021-01-13 | ナカシマプロペラ株式会社 | Propulsion device for ships and ships equipped with it |
US11713101B2 (en) | 2020-12-04 | 2023-08-01 | Jeffrey L. HATHAWAY | Propeller hubcap |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2755868A (en) * | 1953-09-17 | 1956-07-24 | United Aircraft Corp | Spinner construction for an aeronautical propeller |
US3606579A (en) * | 1969-01-22 | 1971-09-20 | Henry Mehus | Propeller |
US3794444A (en) * | 1971-10-04 | 1974-02-26 | Gen Electric | Anti-icing spinner construction |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE606119C (en) * | 1933-11-12 | 1934-11-24 | Nicholas Wladimir Akimoff | Device to increase the efficiency of a screw propeller |
GB652441A (en) * | 1948-05-19 | 1951-04-25 | Edward Shellberg | Air deflectors for airplane propellers |
GB752765A (en) * | 1953-09-17 | 1956-07-11 | United Aircraft Corp | Improvements in or relating to a spinner construction for an aeronautical propeller |
DE3037369A1 (en) * | 1980-09-01 | 1982-03-11 | Escher Wyss Gmbh, 7980 Ravensburg | Low drive marine screw - has set of vanes around rear end of hub smoothing water flow |
CA1289821C (en) * | 1986-07-31 | 1991-10-01 | Michihito Ogura | Screw propeller boss cap with fins |
-
1987
- 1987-07-30 CA CA 543348 patent/CA1289821C/en not_active Expired - Lifetime
- 1987-07-30 EP EP87111052A patent/EP0255136A1/en not_active Withdrawn
- 1987-07-30 AU AU76301/87A patent/AU593670B2/en not_active Expired
- 1987-07-31 GB GB8718165A patent/GB2194295B/en not_active Expired - Lifetime
- 1987-08-12 FR FR8711462A patent/FR2619352A1/en not_active Withdrawn
-
1992
- 1992-06-08 SG SG60592A patent/SG60592G/en unknown
- 1992-11-05 HK HK85092A patent/HK85092A/en not_active IP Right Cessation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2755868A (en) * | 1953-09-17 | 1956-07-24 | United Aircraft Corp | Spinner construction for an aeronautical propeller |
US3606579A (en) * | 1969-01-22 | 1971-09-20 | Henry Mehus | Propeller |
US3794444A (en) * | 1971-10-04 | 1974-02-26 | Gen Electric | Anti-icing spinner construction |
Also Published As
Publication number | Publication date |
---|---|
EP0255136A1 (en) | 1988-02-03 |
CA1289821C (en) | 1991-10-01 |
FR2619352A1 (en) | 1989-02-17 |
GB2194295B (en) | 1991-03-20 |
SG60592G (en) | 1992-09-04 |
GB8718165D0 (en) | 1987-09-09 |
HK85092A (en) | 1992-11-13 |
GB2194295A (en) | 1988-03-02 |
AU7630187A (en) | 1988-02-04 |
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