Micro-channel structure for cavitation suppression of waterjet

Abstract

The application discloses a kind of micro-passage structures of water jet propeller cavitation inhibition, one side of the impeller shell of water jet propeller is communicated with inlet flow channel, the other side is equipped with guide vane body, the outside of guide vane body is equipped with spout, the bottom of the inlet flow channel is equipped with multiple micro-passage structures near impeller shell, and the inlet flow channel is communicated with ship bottom by micro-passage structure.The application provides a kind of micro-passage structure of inhibiting propeller lower half area cavitation, and the water flow of ship bottom is introduced to the inside of inlet flow channel, and jet is formed, impact low pressure area in inlet flow channel and impeller, inhibit the intensity of cavitation in propeller, simple structure can improve propeller thrust and reliability under low speed state.

Description

Technical Field

[0001] This invention relates to a micro-channel structure for suppressing cavitation in waterjet propulsion. By applying waterjet propulsion pump cavitation suppression technology, it can effectively suppress the development of cavitation bubbles inside the propulsion during operation phases such as start-up, parking, and stall, which are subject to cavitation conditions. This can increase propulsion thrust, reduce propulsion vibration, and improve propulsion reliability. It belongs to the field of marine engineering. Background Technology

[0002] Waterjet propulsion utilizes the reaction force generated by a high-speed jet stream to propel a ship forward. It features high efficiency at high speeds, low vibration and noise levels, and good maneuverability. Furthermore, because it can utilize the ram pressure from the incoming flow, waterjet propulsion offers excellent anti-cavitation performance at high speeds, making it widely used in high-performance vessels. However, during low-speed conditions such as startup, parking, and stall, the loss of ram pressure inevitably leads to cavitation in the waterjet propulsion system, affecting its performance.

[0003] During low-speed conditions such as startup and parking, waterjet propulsion systems experience low incoming flow pressure and significantly reduced pressure on the suction surface of the impeller blades, making them highly susceptible to cavitation or even severe cavitation. When severe cavitation occurs in the propulsion system, the converted thrust decreases, mechanical materials are eroded, and very severe unsteady-state characteristics are present. This significantly increases the amplitude of blade pulsation, causing material damage and affecting the reliability of the propulsion system.

[0004] At low speeds, due to the geometry of the inlet flow channel, flow separation easily occurs inside the channel, forming vortices and causing cavitation. Therefore, the cavitation degree in the lower half of the propeller region is relatively stronger. Figure 1 As shown. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to suppress the cavitation intensity inside the propeller in order to improve the thrust and reliability of the propeller at low speeds.

[0006] To address the aforementioned problems, this invention provides a micro-channel structure for suppressing cavitation in a waterjet propulsion system. One side of the impeller housing of the waterjet propulsion system is connected to the inlet channel, and the other side is provided with a guide vane. A nozzle is provided on the outer side of the guide vane. Multiple micro-channel structures are provided at the bottom of the inlet channel near the impeller housing, and the inlet channel is connected to the bottom of the ship through the micro-channel structures.

[0007] Preferably, all micropore structures have the same inner diameter.

[0008] More preferably, the inner diameter d of the microchannel structure is 5% of the diameter of the rotating impeller inside the impeller housing.

[0009] Preferably, the micropore structure is arranged symmetrically about the centerline of the impeller housing.

[0010] More preferably, the angle between adjacent microchannel structures on the diameter of the impeller housing is 10°.

[0011] More preferably, the number of microchannel structures is odd, and the microchannel structure located in the very center is the reference channel, which is set on the center line of the impeller housing.

[0012] More preferably, if the number of microchannel structures is 7, 9 or 11, then the included angle between the two outermost microchannel structures is 60°, 80° or 100°.

[0013] Preferably, the port of the microporous structure that connects to the bottom of the ship is inclined toward the inlet flow channel.

[0014] More preferably, the tilt angle of the micropore structure is no greater than 20°.

[0015] Preferably, the connection between the microporous structure and the bottom of the ship is a rounded structure.

[0016] When the waterjet propulsion unit is in operation, a low-pressure zone is formed at the front of the rotating impeller and the end of the inlet channel due to the suction surface of the rotating impeller. Meanwhile, the pressure at the bottom of the ship is close to the ambient pressure and relatively high. Therefore, a pressure differential flow is formed in the micro-channel structure. The water flow at the bottom of the ship forms a jet that impacts the cavitation vortex in the waterjet propulsion unit through the micro-channel structure.

[0017] This invention provides a microporous structure for suppressing cavitation in the lower half of the propeller. It guides water flow from the bottom of the ship to the inside of the inlet channel and forms a jet that impacts the low-pressure area in the inlet channel and impeller, thereby suppressing the intensity of cavitation inside the propeller. The structure is simple and can improve the thrust and reliability of the propeller at low speeds.

[0018] By placing this micro-channel structure in the propeller inlet channel, the water flow at the bottom of the ship is drawn in, forming a jet impact low-pressure and flow separation region, which suppresses the development of cavitation vortices in the propeller, thereby increasing the propeller thrust and reducing the dynamic flow-induced force of the propeller. Attached Figure Description

[0019] Figure 1 A schematic diagram of cavitation inside a waterjet propulsion system at low speeds;

[0020] Figure 2 A schematic diagram of the micropore structure provided by the present invention;

[0021] Figure 3 This is a front view of the micropore structure distribution structure provided by the present invention;

[0022] Figure 4 A schematic diagram showing the tilt angle of the microporous structure;

[0023] Figure 5The radial dynamic flow excitation spectrum of the guide vane body of a waterjet propulsion system with / without micro-channel structure;

[0024] Figure 6 The radial dynamic flow excitation spectrum of a waterjet propulsion system with / without micro-channel structure;

[0025] Figure 7 This provides comparative data on the efficiency of waterjet propulsion systems with and without micro-channel structures. Figure 1-4 In the middle: 1-nozzle; 2-guide vane body; 3-impeller housing of waterjet propulsion; 4-inlet flow channel; 5-micro-channel structure; 5-1-reference channel; 6-bottom of the ship. Detailed Implementation

[0026] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0027] Example

[0028] like Figure 2-4 As shown, this invention provides a micro-channel structure for cavitation suppression in a waterjet propulsion system. One side of the impeller housing 3 of the waterjet propulsion system is connected to the inlet channel 4, and the other side is provided with a guide vane 2. A nozzle 1 is provided on the outer side of the guide vane 2. Multiple micro-channel structures 5 are provided at the bottom of the inlet channel 4 near the impeller housing 3 (the impeller housing 3 is directly connected to the inlet channel 4, and the micro-channel structures 5 are opened at the inlet channel 4 near the impeller housing 3). The inlet channel 4 is connected to the bottom of the ship 6 through the micro-channel structures 5.

[0029] like Figure 3 As shown, all microchannel structures 5 have the same inner diameter. The inner diameter d of the microchannel structure 5 is 5% of the diameter of the rotating impeller inside the impeller housing 3. The microchannel structures 5 are arranged symmetrically about the centerline of the impeller housing 3. The angle between adjacent microchannel structures 5 on the diameter of the impeller housing 3 is 10°. The number of microchannel structures 5 is odd, and the microchannel structure 5 located in the very center is the reference channel 5-1, which is located on the centerline of the impeller housing 3. Figure 3 The diagram shows 11 microchannel structures, with the angle between the two outermost microchannel structures 5 being 100°. If the installation area is limited, 7 or 9 microchannel structures can be formed (i.e., the angle between the two outermost microchannel structures is 60° or 80°).

[0030] After the duct is constructed, it can be arranged at an angle to accommodate the low-speed operating conditions. The recommended angle of inclination is less than 20°. Figure 4As shown, the port connecting the microchannel structure 5 to the bottom of the ship 6 is inclined towards the inlet channel 4. The inclination angle α of the microchannel structure 5 is 18°. Furthermore, the connection between the microchannel structure 5 and the bottom of the ship 6 is a rounded structure with a rounded diameter equal to the channel diameter d, forming a funnel-shaped opening to draw in low-speed water flow from the bottom of the ship.

[0031] When the waterjet propulsion unit is in operation, a low-pressure zone is formed at the front of the rotating impeller and the end of the inlet channel 4 due to the suction surface of the rotating impeller. Meanwhile, the pressure at the bottom of the ship 5 is close to the ambient pressure and relatively high. Therefore, a pressure differential flow is formed in the micro-channel structure 5. The water flow at the bottom of the ship 6 passes through the micro-channel structure 5 and forms a jet that impacts the cavitation vortex in the waterjet propulsion unit.

[0032] Conventional waterjet propulsion systems that draw in water through the inlet channel can all achieve this. Figure 2-4 The schematic method described above constructs the jet channel; therefore, this invention is applicable to conventional waterjet propulsion systems.

[0033] like Figure 5-7 As shown, the present invention provides a micro-jet channel structure for a waterjet propulsion system, which is placed in the inlet channel of the waterjet propulsion system. Under low-speed conditions, it can suppress the development of cavitation inside the propulsion system, increase the thrust of the propulsion system, and significantly reduce the dynamic flow-induced force amplitude of core components of the propulsion system, such as the impeller and guide vanes.

Claims

1. A microchannel structure for cavitation suppression in a waterjet propulsion system, wherein one side of the impeller housing (3) of the waterjet propulsion system is connected to the inlet channel (4), and the other side is provided with a guide vane (2), and a nozzle (1) is provided on the outer side of the guide vane (2), characterized in that, The bottom of the inlet channel (4) is provided with multiple micro-channel structures (5) near the impeller housing (3), and the inlet channel (4) is connected to the bottom of the ship (6) through the micro-channel structures (5); the micro-channel structures (5) are arranged symmetrically with respect to the center line of the impeller housing (3); the angle between adjacent micro-channel structures (5) on the diameter of the impeller housing (3) is 10°; the port of the micro-channel structure (5) connected to the bottom of the ship (6) is inclined towards the inlet channel (4), and the inclination angle of the micro-channel structure (5) is not greater than 20°.

2. The micropore structure for cavitation suppression of waterjet propulsion as described in claim 1, characterized in that, All micropore structures (5) have the same inner diameter.

3. The micropore structure for cavitation suppression of waterjet propulsion as described in claim 2, characterized in that, The inner diameter d of the microporous structure (5) is 5% of the diameter of the rotating impeller inside the impeller housing (3).

4. The microchannel structure for cavitation suppression of waterjet propulsion as described in claim 1, characterized in that, The number of micropore structures (5) is odd, and the micropore structure (5) located in the middle is the reference channel (5-1), which is set on the center line of the impeller housing (3).

5. The micropore structure for cavitation suppression of waterjet propulsion as described in claim 4, characterized in that, If the number of micropore structures (5) is 7, 9 or 11, then the included angle between the two outermost micropore structures (5) is 60°, 80° or 100°.

6. The microchannel structure for cavitation suppression of waterjet propulsion as described in claim 1, characterized in that, The connection between the microporous structure (5) and the bottom of the ship (6) is a rounded structure.

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