JPS5973393A - Rectifyng device in ship - Google Patents

Abstract

PURPOSE:To enhance the propelling efficiency of a ship, by fitting a ring-like structure in a hull in such a way that a space (d) is defined between the rear end edge of the ring-like structure and a propeller, and as well by providing a plurality of water jet ports in the stern bilge section of the hull, front of the ring- like structure. CONSTITUTION:A ring-like structure 1 is attached to a hull 5 in such a way that a space (d) is defined between the rear end edge of the ring-like structure and a propeller 4, and the ring-like structure 1 is fitted in the hull 5, more than 20% of the length L of the upper section of the ring-like structure 1. Further, a plurality of water jet ports 8 are provided in both sides of the stern bilge section 5' of the hull 5, front of the ring-like structure 1. By water streams jetted from these water jet ports 8 to three-dimentional separation vortices, the generation of three-dimentional vortices may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rectifying device for a ship, particularly an enlarged ship, and relates to a three-dimensional delamination %tl occurring in the stern primordium of an enlarged ship.
The objective is to improve the propulsion performance of ships by eliminating or weakening vortices.

In general, the performance of a ship can be seen by the relationship between the main engine horsepower and the ship's speed.

Naturally, when a ship sails at a ship speed of v5, 11 [)
Assuming that the resistance experienced by the engine body is R5, the required horsepower transmitted from the main engine DHP can be expressed by equation (1).

DHPoζ R5-V5/ 77 - - -
(+,) Here, η is H[advance rate, which can be expressed by equation (2).

η−ηH・η0・η＆・・・(2) It is calculated from the surface, ~-(1-t)/(1-w).

The above η is called the hull efficiency and is an element caused by interference between the propeller and the hull, t is the thrust reduction rate, and W is the wake coefficient. In addition, η is the f11 efficiency of the propeller when it is not affected by the ship's hull, and η is called the propulsion efficiency ratio, which is the efficiency when the propeller operates in a turbulent flow at the stern and Pl, 1. Vera's efficiency η. shows the ratio.

Therefore, in order to reduce the required horsepower for the same speed as one way to improve the performance of ships, it is necessary to reduce the resistance or improve the propulsion efficiency.

Conventionally, for the purpose of improving the performance of ships from this point of view, for example, ducted propellers and spherical bows have been adopted.

In the former case, the propeller is located in the duct 1 to increase the fluid velocity in the duct I to guide it to the propeller operating surface, and η is one of the factors of the propulsion efficiency. The purpose is to improve (the efficiency of condolence in Pl. Copella).

The latter aims to improve the performance of ships by reducing wave-making resistance, which is part of the hull resistance.

Nowadays, many so-called enlarged ships are being built and operated, which are made of lead that is made as large as possible to meet the required dead weight in order to improve the economic efficiency of ships, but in recent years, fuel prices have soared. There is a growing momentum to improve the performance of enlarged ships, whether new ships or existing ships, in order to make them more economical from the viewpoint of energy conservation and energy conservation.

As one means of achieving this, attempts have been made to employ the duct propeller described above, but there are practical problems such as cavity erosion caused by the characteristics of the stern flow field in enlarged ships.

In other words, as shown in Figure 1, the stern flow field of such an enlarged ship consists of parallel drifters circulating around the ship's side and upward flow B circulating around the bilge.
In this square, the longitudinal vortex C is a three-dimensional separated vortex and has large turbulence. This vertical vortex C mixes with the parallel flow and the upward flow B, and the turbulence becomes even more intense.

This kind of turbulence due to mixing occurs almost immediately in front of the propeller, so a region with large wake values is concentrated at the top of the propeller, but generally that region is in a supine position that gradually decreases downward. .

As shown in Part 2, the wake distribution of large ships changes dramatically compared to conventional so-called smart ships, and
In terms of I, there is a flow with a large wake coefficient.

In other words, there is a slow flow in the two parts of the propeller working surface and a fast flow in the lower part of the propeller working surface, and due to these effects, cavitation occurs in the wake concentration area at the top of the propeller. The load on each propeller blade is uneven.

Therefore, the separation of the longitudinal vortex C and the upward flow I3! 1ill increases the hull resistance, and in addition, the uneven flow to the propeller causes an increase in hull vibration and noise.

In such an open space, the interaction between the normal duct propeller propeller and the duct is almost constant in the circumferential direction of the propeller, making it impossible to equalize the flow.

Therefore, ordinary duct propellers are unable to reduce the above-mentioned ship body vibration and noise, and cavity erosion occurs on the inner surface of the duct, making it impossible to withstand long-term use. In addition, there are problems such as high structural strength and high precision required, which increases construction costs.

Furthermore, if a ducted propeller is to be installed on an existing ship, it may be necessary to replace it with a new propeller, specifically a propeller with a larger pitch, in order to maintain an appropriate relationship between the propeller and the main engine rotational speed.

If this happens, with a normal duct propeller, the flow velocity at the propeller position will become excessive, and with the existing duct propeller, the rotation speed will increase by at least about 10% with the same main engine horsepower, making it impossible to achieve the maximum main engine horsepower. As a result, it is not possible to cope with the flow velocity.

Therefore, it is necessary to replace the propeller or increase the engine speed, but in reality such modification work is difficult and requires a large amount of cost. For this reason, whenever a normal duct propeller is used as an existing propeller, it is difficult to achieve optimum performance, which ultimately causes problems in flight operations.

Therefore, it is conceivable to move the duct of a normal ducted propeller forward and position the rear end edge of the duct near the propeller, but with such a structure, the utility force of the duct would have the effect of pulling the ship rearward. becomes stronger, the thrust reduction rate t increases, the hull efficiency ~ decreases, and as a result fl
Since the u-adic 9JJ rate η will deteriorate, it will not be possible to improve the j-rate as intended.

Therefore, in order to solve the problem of ordinary duct propellers and improve the J rate η that propels the duct, it is necessary to
12 as far away from the hull as possible, and then i'
/I+A edge must be located near the propeller.

However, since the distance between the hull and the propeller is limited, the length of the duct is inevitably short. the result,
The thrust generated by the duct itself is small, and the propeller efficiency is also lower than that of a normal duct propeller.
It cannot be put to practical use.

Therefore, the inventors of the present invention have conducted intensive studies on a ship that does not have the above-mentioned drawbacks and has good propulsion efficiency, and have completed the present invention.

That is, in the present invention, the ring-shaped structure is fitted to the hull so that there is a gap between the rear end edge and the propeller, and
The present invention is characterized in that a water jet outlet is provided in front of the ring-shaped structure.

Hereinafter, the present invention will be explained in detail based on the drawings.

Fig. 3 is a side view of the stern of an enlarged ship equipped with the rectifier of the present invention, Fig. 4 is a sectional view along rV-IV in Fig. 3, and Fig. 5 is a sectional view along V-V lji in Fig. 3. Yes, ring-shaped structure 1
has a distance d between its l&edge and the plastic copella 4, and the hull 5 is arranged such that at least 20% of the length of the upper part of the ring-shaped structure 1 fits into the hull 5. Nitorii'
I'm being kicked.

Further, a part of the ring-shaped structure 1 is fixed to the hull 5 via a support member 6. Furthermore, the propeller 4
A rudder 7 is arranged behind the.

When viewed from the lateral direction, the ring-shaped structure 1 has an upper length larger than a lower length k. That is,
The upper length I of the ring-shaped structure 1 is selected from within the range of 0.2 to 1.0 of the diameter of the propeller 4, and is configured such that the length gradually decreases from the top to the bottom. has been done. Further, the ring-shaped structure 1 has a so-called airfoil-shaped cross-sectional shape, in which the inner surface 2 is gently convex and the outer surface 3 is linear.

The above distance d corresponds to the shape of the stern vortex in the stern flowing water.

It is determined by the position, propeller load, and G.

In addition, although the cross-sectional shape of the ring-shaped structure 1 is circular, it is not limited to this shape, and the wake distribution in the stern stream and the shape and thickness of the hull boundary layer are taken into consideration. An appropriate shape such as intramedullary or polygonal shape can be selected.

full of the hull 5 located in front of the ring-shaped structure 1
) A plurality (four in the illustrated case) of water jets 8 are provided on both sides of the tail hilge part 5', and water jets are jetted from the water jets 8 toward the three-dimensional separation vortex, thereby creating a three-dimensional It is configured to prevent the generation of separation vortices.

When the enlarged ship sails, an upward flow B' is generated in the parallel flow around the ship's side, but the parallel flow A' flows approximately parallel to the ship's side of the hull 5, as shown in FIG. A part of it flows as a flow A'' toward the ring-shaped structure 1.

On the other hand, the upward flow B' circulating around the stern bilge part 5' is prevented from generating a three-dimensional separation vortex by the water flow ejected from the water flow outlet 8, and even if it is struck by lightning, three-dimensional separation is weak against lightning. It becomes a vortex and is introduced into the ring-shaped structure 1.

Part A of the parallel flow that has flowed into the ring-shaped structure 1
The weakened three-dimensional separation vortex is rectified by the ring-shaped structure 1 and becomes a uniform flow.
It is supplied to the operating surface of the propeller 4 from the rear end edge of the propeller 4.

Therefore, the propeller 4 rotates in a more uniform flow, and its propulsion efficiency is further improved.

As described above, the present invention includes a link-like structure that is fitted into a ship's hull such that there is a gap between the rear end edge and the propeller, and a water jet outlet provided in front of the ring-like structure. Water flow P, H [21] Since the water flow is ejected toward the three-dimensional separation vortex, the upward flow B around the stern bilge develops into a three-dimensional separation vortex due to the water flow ejected from the water jet. is introduced into the ring-shaped structure while being prevented, and the flow is rectified within the ring-shaped structure.

Therefore, (7) the large propulsion propeller rotates in a rectified and more uniform flow, further improving propulsion efficiency.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the state of the stern flow in a conventional ship, Fig. 2 is a perspective view showing the state of the wake of 4J in a force 1 + ship equipped with the rectifier according to the present invention, and Fig. 3 FIG. 4 is a side view of the stern of an enlarged ship equipped with the rectifying device of the present invention, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a sectional view taken along line V-V in FIG. 3. DESCRIPTION OF SYMBOLS 1... Ring-shaped structure, 2... Inner surface, 3... Outer surface, 4... Propeller, 5... Hull, 6... Support member, 7... Force meter 8.・Water jet outlet. Agent: Patent Attorney Shin Ogawa − Patent Attorney Ken Noguchi Teru Patent Attorney Kazuhiko Saishita

Claims (1)

[Claims] A flow straightening device for a ship, characterized in that a ring-shaped structure is fitted onto a ship's hull with a space between the rear end edge and a propeller, and a water jet outlet is provided in front of the ring-shaped structure. .