JPS6341798B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle device for propulsion of a ship, which includes a nozzle surrounding a screw propeller.

Figures 1 to 3 show conventional ship propulsion nozzle devices. Figures 1 and 3 are side views of the stern of a ship equipped with the nozzle, and Figure 2 is an oblique view of the stern of a ship equipped with the nozzle. It is a perspective view seen from the rear, and the reference numeral 1 in the figure is the hull, 2 is the screw propeller, 3 is the rudder, 4 is the propeller shaft center line, 5 is the propeller shaft, 6 is the bottoming, 7a is the upper stern frame, 7b is a lower stern frame, 8 is a propeller cap, 9 is a shoe piece, 10 is a rudder support member,
11 is a rudder handle, 12 is a nozzle, 12a is a top nozzle cross section, 12b is a bottom nozzle cross section, 12c is a straight side nozzle cross section, 13 is an upper nozzle support member, 1
4 is the lower nozzle support member, 15 is the load water line, 1
6 is the nozzle center line, O is the propeller center position, and θ is the angle between the propeller axis center line 4 and the nozzle center line 16.

FIG. 1 shows a ship having one screw propeller at the rudder stern, in which the screw propeller 2 is equipped with a nozzle 12. Nozzle 1
2 is combined with the propeller 2 in this way, so that not only the propeller 2 but also the nozzle 12 generate thrust when the propeller 2 operates, so it can be used as a propulsion increasing device for a ship, and it can generate a large thrust and the required tugboat or In addition to work boats, the propeller 2 is often employed in large ships where the propeller 2 is relatively small compared to the size of the ship and the load on the propeller 2 is large when in use.

The normal nozzle 12 is configured axially symmetrically, and the centerline of the nozzle 12 coincides with the propeller shaft centerline 4. FIG. 1 shows the most common such case.

However, especially in the stern of large ships, nozzles 12
When installed, the water flow at the stern flowing into the nozzle 12 and the propeller 2 is not uniform, and its flow velocity and direction vary in a complicated manner.

Therefore, an axially symmetrical nozzle 12 as shown in FIG. 1 cannot provide a sufficient effect, and it is necessary to use an asymmetrical nozzle whose cross-sectional shape changes in the circumferential direction to match the flow field at the stern. It is said that there is.

Therefore, a ship propulsion nozzle device as shown in FIG. 2 has been proposed. This means that the diffuser angle of the rear inner surface of the nozzle 12 is set relative to the propeller axis center line at the nozzle top section 12a.
Make it the largest at 6°20′, and the lowest nozzle cross section 12b
In this case, the maximum decrease is 0°, and the true horizontal nozzle cross section 1
2c is configured at 3°10', which is in the middle.

By employing such an asymmetrical nozzle, the efficiency increase is approximately 6% compared to the 2% to 6% increase when using a symmetrical nozzle as shown in Figure 1.
A significant improvement in efficiency of ~9% is expected.

In this way, asymmetric nozzles are extremely effective in cases where the flow is complex, such as at the stern of an enlarged ship.
Since the shape of the nozzle cross section changes in the circumferential direction, it takes a lot of effort to manufacture, and the manufacturing cost is high, making it difficult to put it into practical use.

The system shown in Figure 3 was considered as a countermeasure to this problem, and instead of using an asymmetrical nozzle, the
A symmetrical nozzle similar to that shown in the figure is used, and the centerline 16 of the nozzle is tilted forward and downward from the propeller axis centerline 4 by an angle θ within the same vertical plane.

With this configuration, the nozzle 12
Since the nozzle matches the flow direction at the stern in most cases, it can be expected to improve efficiency to the same extent as an asymmetric nozzle. Further, since the nozzle 12 itself is configured axially symmetrically, its manufacture is easy.

However, in such a tilt nozzle in which the nozzle center line 16 is tilted forward and downward from the propeller axis center line 4, the gap between the blade tip of the propeller 2 and the blade tip changes in the circumferential direction. Gap cavitation is likely to occur during this period, and as a result, cavitation erosion may occur on the inner surface of the nozzle 12. In addition, as a result of the upper leading edge of the nozzle 12 tilting forward, it comes close to the trailing edge of the upper stun frame 7a, but since this part of the hull is fatter than the lower part, there is a risk that the efficiency will be affected by this. This is a problem especially when the gap in this part is small.

The present invention attempts to solve the above-mentioned problems, and aims to provide a nozzle device for ship propulsion that improves propulsion efficiency and simplifies manufacturing.

Therefore, in the ship propulsion nozzle device of the present invention, the front inner surface of the nozzle surrounding the screw propeller is configured axially symmetrically with respect to the propeller axis center line, and the rear inner surface of the nozzle is configured within a vertical plane including the propeller axis center line. The outer surface of the nozzle is located in a vertical plane that includes the propeller shaft center line and is configured to be axially symmetrical with respect to a straight line that is tilted upward and upward relative to the center line of the propeller shaft. The screw propeller is configured axially symmetrically with respect to a straight line, and the tip of the propeller blade of the screw propeller is located forward of the boundary line between the front inner surface and the rear inner surface of the nozzle.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view of a nozzle taken along a vertical plane including the propeller axis center line 4 in order to explain the features of the present invention, and FIG. FIG. 3 is a side view of the stern section showing the first embodiment.

In FIGS. 4 and 5, the same reference numerals as those already described indicate almost the same parts, and 17 is the center line of the outer surface of the nozzle, 18 is the center line of the rear inner surface of the nozzle, and 19a is the topmost part. 19b is the rear inner surface of the nozzle cross section 12a, 20a is the uppermost nozzle cross section 12
20b is the front inner surface at the lowest nozzle cross section 12b, 21a is the outer surface at the uppermost nozzle cross section 12a, 21b is the outer surface at the lowermost nozzle cross section 12b, 22 is the front inner surface 20a, 20b of the nozzle, etc. Rear inner surface 19a of the nozzle,
Boundary lines 4a, 4b, 4c, and 4d with respect to 19b, etc. indicate straight lines parallel to the propeller shaft center line 4.

Furthermore, the character codes in the figure are as follows.

θ ₁ ... Angle between the propeller shaft center line 4 and the center line 17 of the nozzle outer surface θ ₂ ... Angle between the propeller shaft center line 4 and the center line 18 of the rear inner surface of the nozzle θ ₃ ... Nozzle outer surfaces 21a, 21b, etc. is the angle θ ₄ with respect to the center line 17 of the outer surface of the nozzle...the angle l _a of the rear inner surfaces 19a, 19b, etc. of the nozzle with respect to the center line 18 of the rear inner surface of the nozzle...in the direction of the propeller axis center line 4 of the top nozzle cross section 12a Measured length l _b ... Length P measured in the direction of propeller shaft center line 4 of the lowest nozzle cross section 12b ... Point of intersection between propeller shaft center line 4 and center line 17 of the nozzle outer surface Q ... Propeller shaft center Intersection point R ₁ between the line 4 and the center line 18 of the rear inner surface of the nozzle ...Boundary point R ₂ of the front and rear nozzle inner surfaces on the top nozzle cross section 12a ...Boundary point of the front and rear nozzle inner surfaces on the bottom nozzle cross section 12b R ₃ ... Boundary point between the front and rear nozzle inner surfaces on the straight side nozzle cross section 12c As shown in Figures 4 and 5, point P is ahead of propeller center 0, and point Q is behind propeller center 0. The blade tip of the screw propeller 2 is located at the boundary line 2 between the front inner surface and the rear inner surface of the nozzle.
It is positioned further forward than 2.

Then, the nozzle inner surface 20 in front of the boundary line 22
a, 20b are axially symmetrical with respect to the propeller axis center line 4, and the nozzle inner surface 19 behind the boundary line 22;
a, 19b are constructed axially symmetrically with respect to the nozzle rear inner surface centerline 18, and nozzle outer surfaces 21a, 21b are constructed respectively axially symmetrically with respect to the nozzle outer surface centerline 17.

The leading and trailing edges of the nozzle 12 have the same thickness along the circumference, and are arranged at points P and Q so that they are formed by circular arcs with approximately constant radii.
The position of is selected as appropriate.

In this case, the cross-sectional lengths _la , l _b, etc. of the nozzle 12 have relatively close values, but do not necessarily match.

Front inner surface 20a, 20b and rear inner surface 1 of the nozzle
9a and 19b have an angle at the boundary line 22, but are connected by a locally smooth curved surface so as not to cause separation of the water flow.

This nozzle has a shape in which the upper front edge recedes and the lower front edge protrudes forward, and conversely, the upper rear edge protrudes rearward and the lower rear edge moves forward.

By configuring as described above, the diff user angle of the trailing edge of the nozzle is θ ₄ +θ ₂ at the top.
It becomes maximum at θ ₄ −θ ₂ at the bottom, and has an intermediate angle at other positions, and the second
The nozzle surface is set along the stern flow field, almost the same as the asymmetric nozzle shown in the figure, so it acts reliably in the stern flow field like the asymmetric nozzle, and has the same effect as the asymmetric nozzle, that is, propulsion performance. It is possible to obtain the effect of increasing the

In addition, the inclination angle of the nozzle outer surface is the minimum at the top, θ ₃ - θ ₁ , the maximum at the bottom, θ ₃ + θ ₁ , and has an intermediate angle at other positions, depending on the direction of the nozzle 12. matches the flow direction at the stern, so an effect similar to that of the tilt nozzle shown in FIG. 3 can be obtained.

And, because the upper leading edge of the nozzle is retracted,
The gap with the upper stern frame 7a can be increased, and a decrease in efficiency due to interference with the hull can be avoided.

Furthermore, since the blade tip of the propeller 2 is located forward of the boundary line 22 between the front inner surface and the rear inner surface of the nozzle, the nozzle inner surface is symmetrical with respect to the propeller axis center line 4 in this part, and the propeller 2 The gap between the tip of the blade and the inner surface of the nozzle 12 does not change in the circumferential direction, which has the advantage that gap cavitation is less likely to occur.

As described above, according to the ship propulsion nozzle of the present invention, it is possible to obtain a nozzle performance with high propulsion efficiency that is particularly suited to the stern flow field of a large ship, and in addition, all nozzle shapes are axially symmetrical curved surfaces, that is, the front inner surface. , consisting of the rear inner surface and outer surface,
It has the advantage of being easy to manufacture and relatively inexpensive.

Note that FIGS. 6 and 7 are a plan view and a side view showing the aforementioned boundary line 22, respectively.

In addition, FIG. 8 shows the nozzle in FIG. 4 with a solid line, and in correspondence with this, the nozzle in an apparatus according to a second embodiment of the present invention is shown with a dotted line. Points P and Q as point 0
The nozzle shape is shown when the nozzle shape is made to match.

Furthermore, FIG. 9 shows the nozzle in FIG. 4 with a solid line, and in correspondence with this, the nozzle in an apparatus according to a third embodiment of the present invention is shown with a dotted line. , shows the nozzle shape when point P and point Q are exchanged.

In both FIGS. 8 and 9, the boundary line between the front inner surface and the rear inner surface of the nozzle is 22'. Then,
The intersection between the boundary line 22' and the propeller shaft center line 4 is 0.
Since the point is ahead of the intersection point, the propeller center position is moved to point (O) ahead of the intersection point.

Also, in the case of an apparatus equipped with a nozzle as shown by dotted lines in FIGS. 8 and 9, the same effects as in the case of the first embodiment described above can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of a conventional ship propulsion nozzle device, FIG. 2 is a perspective view showing another example of the conventional ship propulsion nozzle device, and FIG. 3 is a side view showing an example of a conventional ship propulsion nozzle device. FIG. 4 is a side view showing another example of a propulsion nozzle device, and FIGS. 4 and 5 show a ship propulsion nozzle device as a first embodiment of the present invention;
FIG. 4 is a longitudinal sectional view of the nozzle, FIG. 5 is a side view thereof, and FIGS. 6 and 7 show the boundary line between the front inner surface and rear inner surface of the nozzle in the apparatus of the present invention. 6 is a plan view thereof, FIG. 7 is a side view thereof, FIG. 8 is an explanatory diagram showing the nozzle of the device as a second embodiment of the present invention with dotted lines, and FIG. It is an explanatory view showing the nozzle of the device as a 3rd example by a dotted line. 1...hull, 2...screw propeller, 3...
...Rudder, 4...Propeller shaft center line, 4a, 4b, 4
c, 4d... straight line parallel to propeller shaft center line 4,
5...Propeller shaft, 6...Bossing, 7a...
Upper stern frame, 7b... lower stern frame, 8... propeller cap, 9... shoe piece, 10... rudder support member, 11... rudder handle, 12...
...Nozzle, 12a...Top nozzle cross section, 12b
... Lowermost nozzle cross section, 13 ... Upper nozzle support member, 14 ... Lower nozzle support member, 15 ... Load water line, 17 ... Center line of nozzle outer surface, 18 ...
...The center line of the rear inner surface of the nozzle, 19a...The rear inner surface at the top nozzle cross section 12a, 19b...
Rear inner surface in the lowest nozzle cross section 12b, 20
a...Front inner surface in the top nozzle cross section 12a, 20b...front inner surface in the bottom nozzle cross section 12b, 21a...outer surface in the top nozzle cross section 12a, 21b...bottom nozzle cross section 12b
outer surfaces 22, 22'... front inner surfaces 20a, 20b of the nozzle and rear inner surfaces 19a, 1 of the nozzle
Boundary line with 9b.

Claims (1)

[Claims] 1 The front inner surface of the nozzle surrounding the screw propeller is configured to be axially symmetrical with respect to the propeller shaft center line, and the rear inner surface of the nozzle is located within a vertical plane that includes the propeller shaft center line and rearward with respect to the propeller shaft center line. The outer surface of the nozzle is configured to be axially symmetrical with respect to a straight line that is tilted upward, and the outer surface of the nozzle is configured to be axially symmetrical with respect to a straight line that is in a vertical plane that includes the centerline of the propeller axis and is tilted forward and downward with respect to the centerline of the propeller axis.
A nozzle device for propulsion of a ship, characterized in that a tip of a propeller blade of the screw propeller is positioned forward of a boundary line between a front inner surface and a rear inner surface of the nozzle.