An optimized diffuser structure for a full-rotation waterjet propulsion system

Abstract

This invention discloses an optimized structure for a diffuser chamber in a full-rotation water jet propulsion device, comprising a diffuser body, which is composed of an inner cylinder, an outer cylinder, a guide ring, a co-current nozzle cover plate, a middle nozzle cover plate, and a counter-current nozzle cover plate, forming a co-current nozzle, a middle nozzle, and a counter-current nozzle. Multiple guide vanes are spaced apart at the middle nozzle. A baffle plate is provided in front of the counter-current nozzle, and a co-current plate is inclinedly provided in front of the middle nozzle. A rounded portion is provided on the side wall of the co-current nozzle cover plate. This invention improves the momentum flux distribution of the inlet flow and reduces the lateral velocity component by placing a flow-following plate in front of the central nozzle and rounding the flow-following nozzle cover plate before the water flows into the central nozzle. It also places a flow-baffle plate in front of the counter-current nozzle to pre-rectify the water flow before it enters the counter-current nozzle and reduce the lateral velocity component. Furthermore, by adjusting the area ratio of the side nozzles, the momentum flux of the water flow exiting the counter-current nozzle is higher than that of the flow-following nozzle, thus eliminating the bias of the thrust of the side nozzles.

Description

Technical Field

[0001] This invention relates to an optimized diffuser structure for a full-rotation waterjet propulsion device, belonging to the field of marine propulsion technology. Background Technology

[0002] The azimuth-rotating waterjet propulsion system is a special type of waterjet propulsion device. Its propulsion principle is similar to that of traditional waterjet propulsion systems: water is drawn in through an inlet located at the center of the propulsion device by an impeller. After the water passes through the impeller and performs work, it enters the diffuser chamber and is then accelerated and ejected from the outlets (three nozzles: one central nozzle and two side nozzles) located on the outer ring of the propulsion device. The difference in water flow flux between the inlet and outlet generates thrust. Figure 1 As shown. The azimuth-rotating waterjet propulsion device changes the orientation of the nozzle by rotating the diffuser, thus changing the direction of the ejected water flow and consequently the direction of the thrust. Because the diffuser can rotate 360° in all directions, the azimuth-rotating waterjet propulsion device can obtain thrust in all 360° directions, achieving "azimuth." Chinese patent application number CN94101405.3 discloses a "waterjet actuator," which provides a relatively clear description of the structural form of the azimuth-rotating waterjet propulsion device. The structure referred to as the guide is the basic form of the diffuser structure involved in this invention and is the basis for carrying out structural optimization.

[0003] However, the water flow entering the diffuser from the impeller outlet has a circumferential velocity component, which causes (1) the ejected water flow from the nozzle to generate a lateral velocity component, thereby generating unexpected lateral thrust; (2) the ejected water flow from the nozzle is asymmetrical, especially the two side nozzles. For the side nozzles, the nozzle direction is the same as the direction of the circumferential velocity component, which is a downstream nozzle, and the ejected water flow flux is higher; the nozzle direction is opposite to the direction of the circumferential velocity component, which is a counter-current nozzle, and the ejected water flow flux is lower. Therefore, the thrust generated by the downstream nozzle is higher than that of the counter-current nozzle. The resultant thrust of the three nozzles is not strictly along the longitudinal symmetry plane in the propulsion device, but is biased towards the downstream nozzle side, that is, the thrust bias phenomenon occurs. The thrust bias causes the propulsion device to exert an additional torque on the ship, reducing the ship's maneuverability.

[0004] Existing diffuser structures adjust the side nozzle area ratio to make the counter-current nozzle area larger than the co-current nozzle area, increasing the flow flux of the water ejected from the counter-current nozzle to eliminate thrust bias, such as the Schottker azimuth jet propulsion system. Figure 2 By arranging guide vanes inside the nozzle to reduce the lateral velocity component, the lateral thrust is reduced (e.g., ...). Figure 3However, while adjusting the side nozzle area ratio solved the problem of different ejection flow fluxes from the two side nozzles, it neglected the lateral velocity component of the ejection flow from the side nozzles, especially the counter-current nozzles, which is one of the causes of lateral thrust. Placing guide vanes in the central nozzle reduced the lateral velocity component of the ejection flow to some extent, but it did not address the asymmetry of the flow flux distribution within the central nozzle relative to the longitudinal symmetry plane, which is one of the causes of thrust bias. Therefore, it is urgent to optimize the diffuser structure to weaken or even eliminate lateral thrust and thrust bias as much as possible. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing diffuser cannot fully recover and eliminate the circumferential velocity component generated by the impeller outlet flow, which leads to a reduction in the effective thrust and maneuverability of the propulsion device for the ship.

[0006] To address the aforementioned technical problems, this invention provides an optimized diffuser structure for a full-rotation waterjet propulsion device, which can weaken or even eliminate lateral thrust and thrust bias, effectively improving thrust and maneuverability.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0008] An optimized structure for a diffuser chamber in a full-rotation waterjet propulsion device includes a diffuser body, which is composed of an inner cylinder, an outer cylinder, a guide ring, a co-current nozzle cover plate, a middle nozzle cover plate, and a counter-current nozzle cover plate. An inner cavity is formed between the inner cylinder wall and the outer cylinder wall of the diffuser body. The inner cavity and the co-current nozzle cover plate, the middle nozzle cover plate, and the counter-current nozzle cover plate respectively form a co-current nozzle, a middle nozzle, and a counter-current nozzle. Multiple guide vanes are spaced apart at the middle nozzle. A baffle plate is provided in front of the counter-current nozzle. The baffle plate is located between the inner cylinder wall and the outer cylinder wall of the diffuser body.

[0009] A flow-following plate is provided in front of the central nozzle. The upper part of the flow-following plate is connected to the lower edge of the flow guide ring, and the lower part of the flow-following plate is connected to the inner wall of the diffuser chamber.

[0010] The side wall of the downstream nozzle cover plate is provided with a rounded part.

[0011] Preferably, the baffle plate reaches the lower edge of the guide ring, and the guide plate covers the space below the guide ring.

[0012] Preferably, the thickness of the baffle plate is not less than the thickness of the outer cylinder wall of the diffuser chamber.

[0013] Preferably, the baffle is a flat plate or a herringbone-shaped plate.

[0014] Preferably, the flow plate is inclined.

[0015] Furthermore, both ends of the flow plate are provided with cover plates, and the two cover plates form a sealed cavity with the flow plate, the guide ring and the inner cylinder wall.

[0016] Furthermore, the tilt direction of the flow-following plate is adapted to the water flow direction in front of the central nozzle.

[0017] Preferably, the downstream nozzle cover includes an upper side plate and a lower side plate, wherein the upper side plate and the lower side plate are spaced apart vertically and one side is sealed.

[0018] Furthermore, the two side walls of the upper and lower side plates, which are different from the sealing side, are respectively connected to the inner cylinder wall and the outer cylinder wall, and the side edge of the upper side plate near the inner cylinder wall is rounded to form the rounded part.

[0019] Furthermore, there is a gap between the rounded sidewall and the lower side plate.

[0020] The present invention provides an optimized diffuser structure for a full-rotation waterjet propulsion device, which has the following advantages:

[0021] 1. In this invention, by arranging a flow-following plate in front of the nozzle of the diffuser chamber optimization structure used in a full-rotation waterjet propulsion device, and rounding the nozzle cover, the water flow is pre-rectified before entering the nozzle, improving the momentum flux distribution of the inlet flow and reducing the lateral velocity component. After the water flow enters the nozzle, it is further rectified by the arranged guide vanes, further reducing the lateral velocity component of the outflow and making the momentum flux distribution more uniform. Compared with simply arranging guide vanes, this invention integrates three optimization structures to improve the outflow of the nozzle, further reducing the lateral thrust generated by the nozzle and solving the problem of centered thrust at the nozzle that was not addressed in the original technology.

[0022] 2. In this invention, by placing a baffle plate in front of the counter-current nozzle in the diffuser chamber of the fully rotating waterjet propulsion device, the water flow is pre-rectified before entering the counter-current nozzle, reducing the lateral velocity component. Simultaneously, by adjusting the side nozzle area ratio, the momentum flux of the water flow exiting the counter-current nozzle is made higher than that of the concurrent nozzle, eliminating the side nozzle thrust bias. Compared to simply adjusting the side nozzle area ratio, this invention, while eliminating the side nozzle thrust bias, also improves the inflow conditions of the counter-current nozzle by placing a baffle plate in front of it, significantly reducing the lateral thrust generated by the side nozzle. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the working principle of a full-rotation water jet propulsion device.

[0024] Figure 2 Schematic diagram of adjusting the side nozzle area ratio to optimize the structure of the existing diffuser;

[0025] Figure 3 A schematic diagram of the arrangement of guide vanes inside the nozzle in the optimized structure of the existing diffuser;

[0026] Figure 4 This is an axonometric schematic diagram illustrating the overall structure of an optimized diffuser chamber for a full-rotation waterjet propulsion device, as shown in the embodiments of the present invention.

[0027] Figure 5 This is a cross-sectional structural diagram illustrating the structure at the counter-flow nozzle when the baffle is a flat plate, as shown in this embodiment of the invention.

[0028] Figure 6 This is a cross-sectional structural diagram of the counter-flow nozzle when the baffle plate is a herringbone plate, which is the main embodiment of the present invention.

[0029] Figure 7 This is a cross-sectional schematic diagram illustrating the structure at the inlet flow plate in the diffuser chamber, which is a key feature of this embodiment of the invention.

[0030] Figure 8 This is an isometric view of the main structure of the downstream nozzle cover plate in an embodiment of the present invention;

[0031] In the picture:

[0032] 1-Diffuser body; 11-Inner cylinder wall; 12-Outer cylinder wall; 2-Guide ring; 3-Co-current nozzle; 4-Intermediate nozzle; 5-Counter-current nozzle; 6-Baffle plate; 7-Co-current nozzle cover plate; 71-Upper side plate; 72-Lower side plate; 8-Intermediate nozzle cover plate; 9-Counter-current nozzle cover plate; 10-Guide plate; 13-Co-current plate; 14-Rounded part. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Reference Figure 4 This application provides an optimized structure for the diffuser chamber of a full-rotation water jet propulsion device, including a diffuser body 1. The diffuser body 1 is composed of an inner cylinder, an outer cylinder, a guide ring 2, a co-current nozzle cover plate 7, a middle nozzle cover plate 8, and a counter-current nozzle cover plate 9. An inner cavity is formed between the inner cylinder wall 11 and the outer cylinder wall 12 of the diffuser body 1. The co-current nozzle 3, the middle nozzle 4, and the counter-current nozzle 5 are respectively formed in the inner cavity and the co-current nozzle cover plate 7, the middle nozzle cover plate 8, and the counter-current nozzle cover plate 9. Multiple guide vanes are welded and fixed at intervals at the middle nozzle 4.

[0035] Reference Figures 4-6In a further embodiment, a baffle plate 6 is arranged in front of the counterflow nozzle 5 between the inner cylinder wall 11 and the outer cylinder wall 12 of the diffuser body 1. The baffle plate 6 can be cast together with the diffuser body 1 or connected to the diffuser body 1 by welding. Its thickness is not less than the thickness of the outer cylinder wall 12 of the diffuser. The height of the baffle plate 6 reaches the lower edge of the guide ring 2 and covers the space below the guide ring 2 to ensure that the water flow will not leak out from here.

[0036] Furthermore, the shape of the baffle 6 can be a simple flat plate, which is easy to process; or it can be a "V" shape or other shapes that conform to the flow direction in front of the counterflow nozzle 5, in order to obtain a better flow guiding effect.

[0037] When the propulsion device is in use, the water flow entering the diffuser from the impeller outlet is split into two in front of the counter-current nozzle 5: one part continues to flow in the direction of impeller rotation and enters the co-current nozzle 3; the other part enters the counter-current nozzle 5. Due to the significant change in flow direction, the water entering the counter-current nozzle 5 experiences an unsmooth flow pattern and enters in a spiral shape, increasing flow losses and inducing a transverse velocity component. Therefore, a baffle plate 6 is installed in front of the counter-current nozzle 5 to pre-rectify the water flow before it enters the nozzle, reducing flow losses and decreasing the transverse velocity component of the outflow.

[0038] Reference Figure 4 and Figure 7 A flow-following plate 13 is inclinedly arranged in front of the central nozzle 4 of the diffuser body 1. The flow-following plate 13 is usually connected to the diffuser body 1 by welding. For small full-rotation water jet propulsion devices, it can also be cast together with the diffuser body 1. The upper part of the flow-following plate 13 is connected to the lower edge of the guide ring 2, and the lower part is connected to the inner cylinder wall 11 of the diffuser. The inclination angle of the flow-following plate 13 is adapted to the water flow direction in front of the central nozzle 4.

[0039] Furthermore, cover plates are welded and fixed at both ends of the flow plate 13, forming a sealed cavity with the flow plate 13, the guide ring 2 and the inner cylinder wall 11.

[0040] Reference Figure 4 and Figure 8 Preferably, the co-current nozzle cover 7 includes an upper side plate 71 and a lower side plate 72. The co-current nozzle cover 7 is formed by bending a long strip plate to form an upper side plate 71 and a lower side plate 72 with an upper and lower gap on one side. The two side walls of the upper side plate 71 and the lower side plate 72, which are different from the sealing side, are welded and fixed to the inner cylinder wall 11 and the outer cylinder wall 12, respectively. The side edge of the upper side plate 71 near the inner cylinder wall 11 is rounded to form a rounded part 14. The rounded part size is as large as possible, but does not interfere with the lower side plate 72. There is a gap between the side wall of the rounded part 14 and the lower side plate 72.

[0041] Reference Figure 3 and Figure 8In existing designs, the placement of guide vanes within the central nozzle 4 reduces the lateral velocity component of the ejected water flow to some extent. However, it fails to address the asymmetry in the flow flux distribution within the central nozzle 4 relative to the longitudinal symmetry plane, which is one of the causes of thrust bias. This invention addresses this by rounding the downstream nozzle cover 7 and placing a downstream plate 13 before the central nozzle 4 to pre-rectify the water flow before it enters the central nozzle 4, further reducing the lateral velocity component of the ejected water flow and mitigating the asymmetry in the flow flux distribution.

[0042] The diffuser optimization structure involved in this invention, based on existing methods such as adjusting the side nozzle area ratio and arranging guide vanes in the central nozzle 4, adds three optimized structures: arranging a baffle plate 6 in front of the counter-current nozzle 5, rounding the co-current nozzle cover plate 7, and arranging a co-current plate 13 in front of the central nozzle 4. After adopting these three optimized structures, model tests verified that the thrust of the waterjet propulsion device increased by approximately 4%; numerical simulation results showed that the lateral thrust and thrust offset distance decreased by 96% and 93% respectively, essentially eliminating them.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An optimized structure for a diffuser chamber in a rotary waterjet propulsion device, comprising a diffuser body (1), the diffuser body (1) being composed of an inner cylinder, an outer cylinder, a guide ring (2), a co-current nozzle cover plate (7), a middle nozzle cover plate (8), and a counter-current nozzle cover plate (9), wherein an inner cavity is formed between the inner cylinder wall (11) and the outer cylinder wall (12) of the diffuser body (1), and a co-current nozzle (3), a middle nozzle (4), and a counter-current nozzle (5) are respectively formed in the inner cavity and the co-current nozzle cover plate (7), the middle nozzle cover plate (8), and the counter-current nozzle cover plate (9), wherein a plurality of guide vanes are spaced apart at the middle nozzle (4), characterized in that, A baffle plate (6) is provided in front of the countercurrent nozzle (5), and the baffle plate (6) is located between the inner cylinder wall (11) and the outer cylinder wall (12) of the diffuser body (1); a co-current plate (13) is provided in front of the middle nozzle (4), the upper part of the co-current plate (13) is connected to the lower edge of the guide ring (2), and the lower part of the co-current plate (13) is connected to the inner cylinder wall (11) of the diffuser body (1); The side wall of the downstream nozzle cover plate (7) is provided with a rounded part (14).

2. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 1, characterized in that, The baffle (6) reaches the lower edge of the guide ring (2) and the guide plate (10) covers the space below the guide ring (2).

3. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 1, characterized in that, The thickness of the baffle plate (6) is not less than the thickness of the outer cylinder wall (12) of the diffuser body (1).

4. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 1, characterized in that, The baffle (6) is a flat plate or a herringbone-shaped plate.

5. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 1, characterized in that, The flow plate (13) is set at an angle.

6. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 5, characterized in that, Both ends of the flow plate (13) are provided with cover plates, and the two cover plates form a closed cavity with the flow plate (13), the guide ring (2) and the inner cylinder wall (11).

7. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 5, characterized in that, The inclined direction of the flow plate (13) is adapted to the water flow direction in front of the central nozzle (4).

8. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 1, characterized in that, The downstream nozzle cover (7) includes an upper side plate (71) and a lower side plate (72), wherein the upper side plate (71) and the lower side plate (72) are spaced apart vertically and one side is sealed.

9. The optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 8, characterized in that, The upper side plate (71) and the lower side plate (72) are connected to the inner cylinder wall (11) and the outer cylinder wall (12) respectively on the side walls of the opposite side of the sealing side. The side edge of the upper side plate (71) near the inner cylinder wall (11) is rounded to form the rounded part (14).

10. An optimized diffuser structure for a full-rotation waterjet propulsion device as described in claim 9, characterized in that, There is a gap between the sidewall of the rounded portion (14) and the lower side plate (72).

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