Accelerating ducted propeller system for propelling boats

Abstract

An accelerating ducted propeller system for propelling boats offers enhanced performance, having the front end of the nozzle disposed at a radial distance (H) between 0.045D and 0.082D from the inner radius of the nozzle, where D is the inner diameter of the nozzle. The front end of the chord of the axial profile of the nozzle has a larger radius than the rear end of the chord with respect to the axis of rotation of the propeller. The inner surface of the nozzle at the axial distance (J) of 0.025D from the rear end of the output edge of the nozzle is at a radial distance from the inner radius of the nozzle of more than 0.0040D and less than 0.0300D. The radial difference between the inner radius of the nozzle and the outer radius of the profile of the nozzle is less than 0.092D.

Claims

1. An accelerating ducted propeller system for propelling boats, the propeller being configured to rotate inside a nozzle, wherein: the nozzle is fixed with respect to a vertical plane that contains an axis of rotation of the propeller; according to a general direction of a water flow while the boat is moving forward, a front end of an input edge of the nozzle is at a radial distance from an inner radius of the nozzle comprised between 0.045D and 0.082D, where D is an inner diameter of the nozzle on a propeller plane and considering the inner radius of the nozzle from the axis of rotation of the propeller to an inner surface of the nozzle on the propeller plane; according to the general direction of the water flow while the boat is moving forward, a front end of a chord of an axial profile of the nozzle has a greater radius than a rear end of the chord, with respect to the axis of rotation of the propeller; considering the general direction of the water flow while the boat is moving forward, the inner surface of the nozzle at an axial distance of 0.025D from a rear end of an output edge of the nozzle is at a radial distance from the inner radius of the nozzle that is greater than 0.0040D and less than 0.0300D, considering the inner radius of the nozzle from the axis of rotation of the propeller to the inner surface of the nozzle on the propeller plane; and on a plane that contains the axis of rotation of the propeller, a radial difference between an inner radius of a profile of the nozzle and an outer radius of the profile of the nozzle is less than 0.092D.

2. The accelerating ducted propeller system for propelling boats according to claim 1, wherein the front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.045D and 0.080D; the inner surface of the nozzle at the axial distance of 0.025D from the rear end of the output edge of the nozzle is at a radial distance from the inner radius of the nozzle that is greater than 0.0060D and less than 0.0250D; and the radial distance between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.090D.

3. The accelerating ducted propeller system for propelling boats according to claim 2, wherein the front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.045D and 0.075D; the inner surface of the nozzle at the axial distance of 0.025D from the rear end of the output edge of the nozzle is at a radial distance from the inner radius of the nozzle that is greater than 0.0080D and less than 0.0200D; and the radial distance between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.088D.

4. The accelerating ducted propeller system for propelling boats according to claim 3, wherein the front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.045D and 0.070D; the inner surface of the nozzle at the axial distance of 0.025D from the rear end of the output edge of the nozzle is at a radial distance from the inner radius of the nozzle that is greater than 0.0100D and less than 0.0175D; and the radial distance between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.086D.

5. The accelerating ducted propeller system for propelling boats according to claim 4, wherein the front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.050D and 0.065D; the inner surface of the nozzle at the axial distance of 0.025D from the rear end of the output edge of the nozzle is at a radial distance from the inner radius of the nozzle that is greater than 0.0130D and less than 0.0150D; and the radial distance between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.082D.

6. The accelerating ducted propeller system for propelling boats according to claim 1, wherein a radial difference between a centre of a chord of the profile of the nozzle and the outer radius of the profile of the nozzle on the same plane perpendicular to the axis of rotation of the propeller that contains the centre of the chord is less than 0.052L, L being an axial length of the nozzle.

7. The accelerating ducted propeller system for propelling boats according to claim 6, wherein the radial difference between the centre of the chord of the profile of the nozzle and the outer radius of the profile of the nozzle on the same plane perpendicular to the axis of rotation of the propeller that contains the centre of the chord is less than 0.040L, L being the axial length of the nozzle.

8. The accelerating ducted propeller system for propelling boats according to claim 7, wherein the radial difference between the centre of the chord of the profile of the nozzle and the outer radius of the profile of the nozzle on the same plane perpendicular to the axis of rotation of the propeller that contains the centre of the chord is less than 0.030L, L being the axial length of the nozzle.

9. The accelerating ducted propeller system for propelling boats according to claim 1, wherein the nozzle of the system is formed by a single ring-shaped profile.

10. The accelerating ducted propeller system for propelling boats according to claim 1, wherein the propeller has a periphery with the greatest radius of each blade, coaxial to the axis of rotation of the propeller, with a length greater than 0.20R for the coaxial periphery, R being a radius of the blades.

11. The accelerating ducted propeller system for propelling boats according to claim 1, wherein on a plane that contains the axis of rotation of the propeller and according to the general direction of the water flow while the boat is moving forward, a radial distance between the inner surface of the nozzle and an outer surface of the nozzle is greater than 0.043D, at an axial distance of 0.066285D downstream from the front end of the input edge of the nozzle; considering the general direction of the water flow while the boat is moving forward and on a plane that contains the axis of rotation of the propeller, an inner line of the axial profile of the nozzle, at a convergent area, upstream from the propeller, is convex toward the axis of rotation of the propeller in more than 25% of an axial length thereof; and the propeller plane is at a distance greater than 0.38L and less than 0.70L from the front end of the input edge of the nozzle.

12. The accelerating ducted propeller system for propelling boats according to claim 11, wherein the radial distance between the inner surface of the nozzle and the outer surface of the nozzle is greater than 0.044D, at an axial distance of 0.066285D downstream from the front end of the input edge of the nozzle; the inner line of the axial profile of the nozzle, at the convergent area, upstream from the propeller, is convex towards the axis of rotation of the propeller in more than 30% of the axial length thereof; and the propeller plane is at a distance greater than 0.40L and less than 0.65L from the front end of the input edge of the nozzle.

13. The accelerating ducted propeller system for propelling boats according to claim 12, wherein the radial distance between the inner surface of the nozzle and the outer surface of the nozzle is greater than 0.045D, at an axial distance of 0.066285D downstream from the front end of the input edge of the nozzle; the inner line of the axial profile of the nozzle, at the convergent area, upstream from the propeller, is convex towards the axis of rotation of the propeller in more than 60% of the axial length thereof; and the propeller plane is at a distance greater than 0.42L and less than 0.60L from the front end of the input edge of the nozzle.

14. The accelerating ducted propeller system for propelling boats according to claim 13, wherein the radial distance between the inner surface of the nozzle and the outer surface of the nozzle is greater than 0.048D, at an axial distance of 0.066285D downstream from the front end of the input edge of the nozzle; the inner line of the axial profile of the nozzle, at the convergent area, upstream from the propeller, is convex towards the axis of rotation of the propeller in more than 99% of the axial length thereof; and the propeller plane is at a distance greater than 0.44L and less than 0.55L from the front end of the input edge of the nozzle.

15. The accelerating ducted propeller system for propelling boats according to claim 14, wherein the radial distance between the inner surface of the nozzle and the outer surface of the nozzle is greater than 0.051D, at an axial distance of 0.066285D downstream from the front end of the input edge of the nozzle; the inner line of the axial profile of the nozzle, at the convergent area, upstream from the propeller, is convex towards the axis of rotation of the propeller in 100% of the axial length thereof; and the propeller plane is at a distance greater than 0.45L and less than 0.52L from the front end of the input edge of the nozzle.

16. The accelerating ducted propeller system for propelling boats according to claim 1, wherein, considering the general direction of the water flow while the boat is moving forward, more than 80% of the inner surface of the nozzle downstream from the propeller to the output edge is continuously divergent.

17. The accelerating ducted propeller system for propelling boats according to claim 16, wherein the inner surface of the nozzle downstream from the propeller is conical.

18. The accelerating ducted propeller system for propelling boats according to claim 1, wherein on the plane that contains the axis of rotation of the propeller, the radial difference between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.184L.

19. The accelerating ducted propeller system for propelling boats according to claim 18, wherein the radial difference between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.176L.

20. The accelerating ducted propeller system for propelling boats according to claim 19, wherein the radial difference between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.170L.

21. The accelerating ducted propeller system for propelling boats according to claim 20, wherein the radial difference between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.148L.

22. The accelerating ducted propeller system for propelling boats according to claim 21, wherein the radial difference between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is less than 0.144L.

23. The accelerating ducted propeller system for propelling boats according to claim 1, wherein, considering the general direction of the water flow while the boat is moving forward, the outer surface of the nozzle, on a margin of the input edge and output edge, has a lower inclination with respect to the axis of rotation of the propeller on a part next to the input edge than on the rest of the output edge.

24. The accelerating ducted propeller system for propelling boats according to claim 23, wherein the outer surface of the nozzle, on the margin of the input edge and output edge, is substantially cylindrical on a front part next to the input edge, with an axial length greater than 0.038L and less than 0.25L.

25. The accelerating ducted propeller system for propelling boats according to claim 24, wherein the outer surface of the nozzle, downstream from the substantially cylindrical surface, is substantially conical to the output edge.

26. The accelerating ducted propeller system for propelling boats according to claim 1, wherein, according to the general direction of the water flow while the boat is moving forward, the output edge of the nozzle is substantially blunt.

27. The accelerating ducted propeller system for propelling boats according to claim 26, wherein the output edge has a substantially toroidal-shaped surface and a radius of curvature of said surface is less than 0.012D.

28. The accelerating ducted propeller system for propelling boats according to claim 1, wherein, considering the general direction of the water flow while the boat is moving forward, a convergent inner surface of a front part of the nozzle is joined to the outer surface of the nozzle by a toroidal-shaped surface, forming the input edge for water in the nozzle; and all or part of the inner surface of the nozzle that surrounds the propeller is cylindrical with the smallest inner radius of the nozzle.

29. The accelerating ducted propeller system for propelling boats according to claim 1, wherein the coordinates of the profile of the nozzle are: a value of the abscissae is established at 100X/L, taking the values of X from the input edge; 100Yi/L for a value of the inner ordinates; and 100Yu/L for a value of outer ordinates TABLE-US-00003 100X/L 100 Yi/L 100YU/L 0.000 10.950  10.950 2.083 7.605 13.033 5.807 5.377 13.033 9.532 3.900 13.033 13.257 2.800 13.033 16.981 1.977 12.900 20.706 1.300 straight line 24.431 0.763 ″ 28.155 0.370 ″ 31.880 0.111 ″ 36.874 0.000 ″ 50.000 0.000 ″ 60.000 0.000 ″ 70.000 straight line ″ 80.000 ″ ″ 90.000 ″ ″ 99.074 3.000 4.869 100.000 3.926 3.926 a centre of rotation of a radius of a circumference that creates a toroidal surface of the input edge is established on the abscissa 100X/L=2.083 and ordinate 100Y/L=10.950; a length of the radius has the same value as the abscissa; a centre of rotation of a radius of a circumference that creates a toroidal surface of the output edge is established on the abscissa 100X/L=99.074 and ordinate 100Y/L=3.926; and an axial length of the nozzle is 0.50D and thus L/D=0.5.

30. The accelerating ducted propeller system for propelling boats according to claim 1, wherein, considering the general direction of the water flow while the boat is moving forward, a front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.055D and 0.080D.

31. The accelerating ducted propeller system for propelling boats according to claim 30, wherein the front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.057D and 0.080D.

32. The accelerating ducted propeller system for propelling boats according to claim 31, wherein the front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.060D and 0.075D.

33. The accelerating ducted propeller system for propelling boats according to claim 32, wherein the front end of the input edge of the nozzle is at a radial distance from the inner radius of the nozzle comprised between 0.065D and 0.075D.

34. The accelerating ducted propeller system for propelling boats according to claim 33, wherein the coordinates of a profile of the nozzle are: a value of the abscissae is established at 100X/L, taking the values of X from the input edge; 100Yi/L for a value of the inner ordinates; and 100Yu/L for a value of outer ordinates TABLE-US-00004 100X/L 100 Yi/L 100YU/L 0.000 14.000  14.000 2.269 — 16.269 4.214 8.006 16.269 10.697 4.214 16.269 13.197 — 16.114 17.018 1.900 straight line 25.000 0.500 ″ 36.791 0.000 ″ 40.000 0.000 ″ 50.000 0.000 ″ 56.791 0.000 ″ 60.000 straight line ″ 70.000 ″ ″ 80.000 ″ ″ 90.000 ″ ″ 99.074 3.000 4.869 100.000 3.926 3.926 a centre of rotation of a radius of a circumference that creates a toroidal surface of the input edge is established on the abscissa 100X/L=2.269 and ordinate 100Y/L=14.000; a length of the radius has the same value as the abscissa; a centre of rotation of a radius of a circumference that creates a toroidal surface of the output edge is established on the abscissa 100X/L=99.074 and ordinate 100Y/L=3.926; and an axial length of the nozzle is 0.50D.

35. The accelerating ducted propeller system for propelling boats according to claim 1, wherein the nozzle is fixed with respect to a hull of the boat.

36. The accelerating ducted propeller system for propelling boats according to claim 1, wherein the nozzle forms part of a directional thruster, also known as azimuth thruster.

37. The accelerating ducted propeller system for propelling boats according to claim 1, wherein it forms part of a boat with a motor that is joined it and provides rotational movement to a propeller shaft.

38. A boat that comprises at least a motor joined to a shaft for producing rotational movement of a propeller with a nozzle, according to claim 1.

39. The boat, which has from two to ten ducted propeller systems, according to claim 38.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To complement the description provided herein, and for the purpose of helping to make the features of the disclosure more readily understandable, said description is accompanied by a set of drawings constituting an integral part of the same, which by way of illustration and not limitation represents the following:

(2) FIG. 1 is a schematic profile representation of an accelerating nozzle fixed with respect to the hull of a boat, on a plane that contains the axis of rotation of the propeller and which corresponds to the first previously indicated coordinates for the profile of the nozzle; and part of the propeller blade is also represented.

(3) FIG. 2 is a schematic representation of the fixed pitch propeller assembly, nozzle and nozzle supports, viewed from downstream, while the boat is moving forward.

(4) FIG. 3 is a schematic representation of the accelerating ducted propeller system, the nozzle shown vertically cut by a plane that contains the axis of rotation of the nozzle; the figure represents the propeller with blades and core (cube), the rear support of the propeller shaft, the sternpost, a support for the nozzle and the rudder; forming part of a boat, so that the details of the assembly can be clearly seen.

(5) FIG. 4 is a profile representation of the profile of the nozzle shown vertically cut by a plane that contains the axis of rotation of the propeller, with a suitable inner structural distribution to make the material rigid and light and to use less material. The nozzle profile used in all of FIGS. 1 to 4 is defined by the first coordinates.

(6) FIG. 5 is a representation of a profile of a pointed-type blade.

(7) FIG. 6 is a schematic representation of the nozzle profile of the second coordinates, as an alternative embodiment.

(8) FIG. 7 is a schematic representation of the profile of the 19A nozzle which, as was previously stated, belongs to the state of the art.

(9) FIG. 8 is a schematic representation of the profile of the nozzle of document ES2460815, belonging to the state of the art.

DETAILED DESCRIPTION OF THE DRAWINGS

(10) FIG. 1 shows the nozzle 1 fixed with respect to the hull of the boat; a propeller blade 2 with its input edge 10 and its output edge 11, with its pressure face 12; the dashed line 4 which represents the propeller plane perpendicular to the axis of rotation 9 of the propeller; the blade tip 3 in this case being coaxial to the axis of rotation of the propeller and to the inner walls of the nozzle, section 1.00R of the blades; the blades not having an axial rake nor a circumferential skew; and it also shows the front end 5 of the input edge of the nozzle when the boat is moving forward; the rear end 6 of the output edge of the nozzle when the boat is moving forward; the outer surface 7 of the nozzle; the inner surface 8 of the nozzle; the axial distance E from the propeller plane 4 to the front end 5 of the input edge of the nozzle, which in this embodiment equals 0.2299D, D being the inner diameter of the nozzle, this value 0.2299D being illustrative and non-limiting, expressed as a function of L equals 0.4598L; the axial distance Q from the front end 5 of the input edge of the nozzle to an axial distance downstream of 0.066285D; the radial distance Z with a value of 0.051D, between the inner surface of the nozzle and the outer surface of the nozzle, to the aforementioned axial distance Q; the axial length L of the nozzle which equals 0.50D; the radial distance H from the front end 5 of the input edge of the nozzle to the inner radius of the nozzle, which in this embodiment equals 0.055D; the total axial length of the divergence of the inner walls of the nozzle continuously equal 0.40L; all according to the aforementioned first coordinates and with the value of the axial length L of the nozzle equal to 0.50D, on which this embodiment is based. It can be seen how the inner walls 8 in the convergent area are convex according to the direction of the flow in the front part of the nozzle, the surface of the part that surrounds the blade tips later becoming cylindrical, and later divergent with a conical surface to the output edge 6; in this figure it can be seen how the outer surface 7 of the profile keeps its radius downstream from the input edge to the abscissa 100X/L=13.257 with a cylindrical surface, the radius thereof then becoming smaller until the output edge of the nozzle with a conical surface.

(11) The blade tips are covered by the cylindrical inner surface of the nozzle.

(12) The axis of rotation 9 of the propeller that in this case coincides with the axis of symmetry of the nozzle can also be seen.

(13) The inner surface of the nozzle at the axial distance J of 0.025D from the rear end 6 of the output edge of the nozzle is at a radial distance K of 0.0134D from the inner radius of the nozzle

(14) The radial difference between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is 0.130L

(15) The clearance between the blade tips of the propeller and the nozzle is in practice less than 0.5% of the inner diameter of the nozzle.

(16) FIG. 2 shows the fixed pitch propeller with four blades 2, the blade tips 3 arched and equidistant from the cylindrical inner surface 8 of the nozzle, the direction of rotation of the blades indicated by the arrow 14, the core 13 of the propeller, and the supports 15 of the nozzle 1 that fix the nozzle to the stern of the boat, not shown in this figure; the input edge 10 of the blade, the output edge 11 of the blade, the outer surface 7 of the nozzle; and the inner surface 8 of the nozzle. In this figure the four blades all show the pressure face 12, since it is a view from downstream.

(17) FIG. 3 shows the nozzle 1 vertically cut (all nozzles are hollow, not solid); and the propeller with its blades in this view; the upper blade showing the pressure face 12 thereof, the lower blade showing the suction face 18 thereof, since the propeller rotates clockwise when seen from downstream; the rudder 20 and its post 16, one of the two supports 15 of the nozzle and the sternpost 19 that forms part of the boat. The propeller core (central part of the propeller) is joined to the shaft and the shaft to the motor of the boat. The drive shaft passes inside a support 17 in the stern of the hull. It also indicates the general direction of the water with four arrows, the outer surface 7 of the nozzle, the inner surface 8 of the nozzle, the front end 5 of the input edge of the nozzle and the rear end 6 of the output edge of the nozzle. According to the ducted propeller system, when the propeller rotates it creates less static pressure in front of the nozzle, creating a depression in the convergent inner surface, the pressure difference with the rest of the walls creates an axial component that thrusts the nozzle forward and therefore the boat by means of the supports that join the nozzle to the stern of the boat. Both the propeller and the nozzle thrust the boat. The ducted propeller system forms part of the boat.

(18) FIG. 4 shows the profile of the nozzle proposed 1, with the radial difference S between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle that equals 0.130L; said nozzle shown cut by a plane that contains the axis of rotation of the propeller, with an inner structural distribution that is suitable to make it light and resistant and to use less material; the input edge of the nozzle and the output edge are made up of two substantially metal toric pieces, joined to metal plates that follow the profile of the indicated nozzle both on the outside and on the inside; between the metal plates that make up the outer and inner surface of the nozzle, two metal rings are arranged that join both the inner and outer sides of the profile of the nozzle so as to provide structural rigidity to the assembly.

(19) FIG. 5 shows a pointed profile on the side of the pressure face 12, the side of the suction face 18, and the input edge 10 and the output edge 11, relatively sharpened.

(20) FIG. 6 shows a ducted propeller system, wherein the profile of the nozzle is defined by the previously mentioned second coordinates, as an alternative embodiment for applications where the boat sails mainly with high load indices. Everything is the same as FIG. 1, except the inner surface of the nozzle at the axial distance J of 0.025D from the rear end of the output edge of the nozzle, which is at a radial distance K of 0.0135D from the inner radius of the nozzle; the axial distance E that equals 0.2344D and is illustrative and non-limiting, expressed as a function of L is 0.4689L; the radial distance H between the front end of the input edge and the inner radius of the nozzle which equals 0.070D; the radial distance Z which equals approximately 0.058D; and the radial distance between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle which equals 0.163L.

(21) In FIG. 7 the same numerical references refer to the same elements as in the preceding figures and the same letter references refer to the same concepts as in the preceding figures; it shows that the 19A nozzle belongs to the state of the art, wherein the axial distance E equals 0.25D; the axial distance Q from the front end 5 of the input edge of the nozzle to an axial distance downstream of 0.066285D; the radial distance Z with a very approximate value of 0.073D, between the inner surface of the nozzle and the outer surface of the nozzle at the aforementioned axial distance Q; the axial length L of the nozzle that equals 0.50D; the radial distance H between the front end of the input edge of the nozzle and the inner radius of the nozzle that equals 0.091D; the inner surface of the nozzle at the axial distance J of 0.025D from the rear end of the output edge of the nozzle is at a radial distance K of 0.0093D from the inner radius of the nozzle, considering the inner radius of the nozzle from the axis of rotation of the propeller. The radial difference between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle is 0.210L.

(22) All of these data are calculated based on the published coordinates and using the ratio L/D=0.5, corresponding to the 19A nozzle. The 19A nozzle has a cylindrical inner surface from 0.40L to 0.60L to cover the blade tips of the propeller.

(23) In FIG. 8, from state of the art document ES2460815, it can be seen that the front end of the input edge of the nozzle is at a radial distance H of 0.053D from the inner radius of the nozzle; the axial length L of the nozzle equals 0.4970D; and the axial distance E equals 0.2281D.

(24) This figure also shows the axial distance Q from the front end of the input edge of the nozzle to an axial distance downstream of 0.066285D; the radial distance Z with a very approximate value of 0.040D, between the inner surface of the nozzle and the outer surface of the nozzle to the aforementioned axial distance Q.

(25) The radial distance between the inner radius of the profile of the nozzle and the outer radius of the profile of the nozzle equals 0.128L, according to the coordinates of document ES2460815.

(26) In fluid mechanics, specific subtle changes lead to highly significant behavioural changes. Specific variations that seem insignificant can produce radical changes in the behaviour of the fluid.