Micropore structure for cavitation suppression of water-jet propeller

Abstract

One side of an impeller shell of the water-jet propeller is communicated with an inlet flow channel, a guide vane body is arranged on the other side of the impeller shell, a nozzle is formed in the outer side of the guide vane body, and a plurality of micro-channel structures are arranged at the position, close to the impeller shell, of the bottom of the inlet flow channel. And the inlet flow channel is communicated with the ship bottom through the micro-channel structure. The invention provides a microchannel structure for inhibiting cavitation bubbles in the lower half area of the propeller, water flow at the bottom of a ship is guided to the inner side of an inlet flow channel, jet flow is formed, the low-pressure area in the inlet flow channel and an impeller is impacted, the cavitation intensity in the propeller is inhibited, the structure is simple, and the thrust and reliability of the propeller in a low-navigational-speed state can be improved.

Description

Technical Field

[0001] The present invention relates to a micro-channel structure for suppressing cavitation in a water jet propulsion system. By applying the cavitation suppression technology of a water jet propulsion pump, the micro-channel structure can effectively suppress the development of cavitation bubbles inside the propeller during operation stages such as startup, stationary navigation, and stall of the water jet propulsion system, thereby increasing the propeller thrust, reducing the propeller vibration, and improving the propeller reliability. The micro-channel structure belongs to the field of ship engineering. Background Art

[0002] Waterjets propel ships forward using the reaction force generated by a high-speed jet stream. They offer high efficiency at high speeds, low vibration and noise levels, and excellent maneuverability. Furthermore, because they can utilize incoming flow pressure, waterjets offer significant anti-cavitation benefits at high speeds, making them widely used in high-performance ships. However, at low speeds, such as during startup, stationary, and stall conditions, the loss of incoming flow pressure inevitably causes waterjets to cavitate, impacting propulsion performance.

[0003] When the water jet propulsion system is in low-speed operation conditions such as starting and stationary, the incoming flow pressure is small and the pressure on the suction surface of the impeller blade is significantly reduced, which makes cavitation very likely to occur or even severe cavitation. When severe cavitation occurs in the propeller, the converted thrust decreases, the mechanical material is eroded, and it is accompanied by very severe non-steady-state characteristics, which significantly enhances the blade pulsation amplitude, causes material damage, and affects the propeller and reliability.

[0004] At low speeds, affected by the geometry of the inlet flow channel, flow separation is likely to occur inside the flow channel, forming vortices and causing cavitation. Therefore, the degree of cavitation in the lower half of the propeller is relatively stronger, such as Figure 1 shown. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to suppress the cavitation intensity in the propeller to improve the thrust and reliability of the propeller under low speed conditions.

[0006] In order to solve the above problems, the present invention provides a micro-channel structure for suppressing cavitation of a water jet propulsion system. One side of the impeller housing of the water jet propulsion system is connected to the inlet flow channel, and the other side is provided with a guide vane body. The outer side of the guide vane body is provided with a nozzle. The bottom of the inlet flow channel is provided with multiple micro-channel structures near the impeller housing, and the inlet flow channel is connected to the bottom of the ship through the micro-channel structure.

[0007] Preferably, the inner diameters of all microchannel structures are the same.

[0008] More preferably, the inner diameter d of the micro-channel structure is 5% of the diameter of the rotating impeller in the impeller housing.

[0009] Preferably, the micro-channel structures are arranged symmetrically about the center line of the impeller housing.

[0010] More preferably, the micro-channel structures are arranged on a diameter of the impeller housing, and an angle between adjacent micro-channel structures is 10°.

[0011] More preferably, the number of the micro-channel structures is odd, and the micro-channel structure located in the middle is the reference channel, which is arranged on the center line of the impeller housing.

[0012] More preferably, the number of the micro-channel structures is 7, 9 or 11, and the angle between the two outermost micro-channel structures is 60°, 80° or 100°.

[0013] Preferably, the port of the micro-channel structure communicating with the bottom of the ship is inclined toward the inlet flow channel.

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

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

[0016] When the waterjet propulsion system is in operation, affected by the suction surface of the rotating impeller, a low-pressure area is formed in front of the rotating impeller and at the end of the inlet flow channel, while the pressure at the bottom of the ship is close to the ambient pressure and is relatively high. Therefore, a pressure differential flow is formed in the micro-channel structure, and the water flow at the bottom of the ship passes through the micro-channel structure to form a jet impacting the cavitation vortex in the waterjet propulsion system.

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

[0018] The micro-channel structure is placed in the propeller inlet flow channel to guide the water flow under the ship, forming a jet impact low-pressure and flow separation area, inhibiting the development of cavitation vortices in the propeller, thereby increasing the propeller thrust and reducing the propeller dynamic flow excitation force. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of cavitation in a water jet propulsion system at low speed;

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

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

[0022] Figure 4 Schematic diagram of the inclination angle of the microchannel structure;

[0023] Figure 5The radial dynamic flow excitation spectrum of the guide vane of the water jet propulsion system with and without micro-channel structure;

[0024] Figure 6 The impeller radial dynamic flow excitation spectrum of the water jet propulsion system with and without micro-channel structure;

[0025] Figure 7 The figures are comparative data of water jet propulsion efficiency when the water jet propulsion system is equipped with or without micro-channel structure. Figure 1-4 Middle: 1-nozzle; 2-guide vane; 3-impeller housing of waterjet propulsion; 4-inlet flow channel; 5-micro-channel structure; 5-1-reference channel; 6-ship bottom. DETAILED DESCRIPTION

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

[0027] Example

[0028] like Figure 2-4 As shown, a micro-pore structure for cavitation suppression of a water jet propulsion system provided by the present invention is provided. One side of the impeller housing 3 of the water jet propulsion system is connected to the inlet flow channel 4, and the other side is provided with a guide vane body 2. The outer side of the guide vane body 2 is provided with a nozzle 1. A multi-channel micro-pore structure 5 is provided at the bottom of the inlet flow channel 4 near the impeller housing 3 (the impeller housing 3 is directly connected to the inlet flow channel 4, and the micro-pore structure 5 is opened in the inlet flow channel 4 near the impeller housing 3). The inlet flow channel 4 is connected to the bottom 6 of the ship through the micro-pore structure 5.

[0029] like Figure 3 As shown, all micropore structures 5 have the same inner diameter. The inner diameter d of each micropore structure 5 is 5% of the diameter of the rotating impeller within the impeller housing 3. The micropore structures 5 are arranged symmetrically about the centerline of the impeller housing 3. Adjacent micropore structures 5 form an angle of 10° along the diameter of the impeller housing 3. There are an odd number of micropore structures 5, with the central micropore structure 5 being the reference channel 5-1, located on the centerline of the impeller housing 3. Figure 3 The figure shows 11 micro-channel structures, with the angle between the two outermost micro-channel structures 5 being 100°. If the installation area is limited, 7 or 9 micro-channel structures can be formed (i.e., the angle between the two outermost micro-channel structures is 60° or 80°).

[0030] After the channel is established, the channel can be arranged tilted to adapt to the low-speed operating conditions of the main operation. The tilt angle is recommended to be less than 20°. Figure 4As shown, the port connecting the micro-channel structure 5 to the ship's bottom 6 is inclined toward the inlet flow channel 4. The inclination angle α of the micro-channel structure 5 is 18°. Furthermore, the connection between the micro-channel structure 5 and the ship's bottom 6 is rounded, with a diameter equal to the channel diameter d, forming a bell-shaped mouth to draw in low-speed water from the ship's bottom.

[0031] When the waterjet propulsion system is in operation, affected by the suction surface of the rotating impeller, a low-pressure area is formed in front of the rotating impeller and at the end of the inlet flow channel 4, while the pressure at the bottom of the ship 5 is close to the ambient pressure and is relatively high. Therefore, a pressure differential flow is formed in the micro-channel structure 5, and the water flow at the bottom of the ship 6 passes through the micro-channel structure 5 to form a jet impacting the cavitation vortex in the waterjet propulsion system.

[0032] Conventional water jet propulsion systems that draw water through the inlet flow channel can be Figure 2-4 The jet channel is constructed using the schematic method in FIG. , therefore, the present invention can be applied to conventional water jet propulsion devices.

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

Claims

1. A micro-channel structure for suppressing cavitation in a water jet propulsion system, wherein one side of an impeller housing (3) of the water jet propulsion system is connected to an inlet flow channel (4), and the other side is provided with a guide vane (2), and the outer side of the guide vane (2) is provided with a nozzle (1), characterized in that: A multi-channel microporous structure (5) is provided at the bottom of the inlet flow channel (4) near the impeller housing (3), and the inlet flow channel (4) is connected to the bottom of the ship (6) through the microporous structure (5).

2. The micro-channel structure for suppressing cavitation in a water jet according to claim 1, wherein: All micro-channel structures (5) have the same inner diameter.

3. The micro-channel structure for suppressing cavitation in a water jet according to claim 2, wherein: The inner diameter d of the microporous structure (5) is 5% of the diameter of the rotating impeller in the impeller housing (3).

4. The micro-channel structure for suppressing cavitation in a water jet according to claim 1, wherein: The micro-channel structure (5) is arranged symmetrically with respect to the center line of the impeller housing (3).

5. The micro-channel structure for suppressing cavitation in a water jet according to claim 4, characterized in that: The micro-channel structures (5) are on the diameter of the impeller housing (3), and the angle between adjacent micro-channel structures (5) is 10°.

6. The micro-channel structure for suppressing cavitation in a water jet according to claim 5, characterized in that: The number of the micro-channel structures (5) is odd, and the micro-channel structure (5) located in the middle is a reference channel (5-1), which is arranged on the center line of the impeller housing (3).

7. The micro-channel structure for suppressing cavitation in a water jet according to claim 6, wherein: The number of the micro-channel structures (5) is 7, 9 or 11, and the angle between the two outermost micro-channel structures (5) is 60°, 80° or 100°.

8. The micro-channel structure for suppressing cavitation in a water jet according to any one of claims 1 to 7, characterized in that: The port of the microporous structure (5) communicating with the bottom of the ship (6) is inclined toward the inlet flow channel (4).

9. The micro-channel structure for suppressing cavitation in a water jet according to claim 8, wherein: The inclination angle of the micro-channel structure (5) is no greater than 20°.

10. The micro-channel structure for suppressing cavitation in a water jet according to claim 1, wherein: The connection between the micro-channel structure (5) and the bottom of the ship (6) is a rounded structure.

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