Pump-jet rotor tip vortex control device based on blade tip wing

Abstract

This invention discloses a tip vortex control device for a pump-jet propulsion rotor based on a blade tip wing. Under the premise that the open-water performance of the pump-jet propulsion meets the requirements for rapid response, a tip wing is added to the pressure surface side at the tip of the rotor blade. The starting point of the tip wing at its leading edge root is positioned backward relative to the leading edge of the rotor blade tip, and the trailing edge root is positioned forward relative to the trailing edge of the rotor blade tip. The leading edge of the tip wing is backward-sloping and its profile forms an angle with the rotor blade rib line, while the trailing edge is forward-sloping and its profile forms an angle with the rotor blade rib line. The airflow-facing surface of the lower end face of the tip wing's leading edge is of the NACA airfoil type, and the upper end face of the tip wing maintains the same profile and clearance height as the inner wall of the duct. This invention, without increasing the structural complexity, design burden, or weight of the pump-jet propulsion, can effectively control the generation and development of tip vortices and effectively suppress pressure pulsations and unsteady flow excitation caused by tip vortices, facilitating engineering applications.

Description

Technical Field

[0001] The invention belongs to the field of pump-jet propulsion design, and in particular relates to a pump-jet rotor tip vortex control device based on a blade tip wing. Background Art

[0002] like Figure 1 As shown in Figure 1, the pump-jet propulsion system is mainly composed of a rotor, a stator and a duct (see Figure 1 ). Compared with traditional propeller propulsion, pump-jet propulsion can increase the critical speed of underwater vehicles, reduce the noise caused by underwater vehicle propellers, and improve the acoustic stealth of underwater vehicles.

[0003] The excitation source characteristics of pump-jet propulsion are complex. Among them, the tip gap vortex between the rotor and the inner wall of the duct can cause pressure pulsation and tip vortex cavitation, which not only increases the unsteady force of the rotor, but also produces unsteady excitation on the duct, causing structural vibration of non-rotating parts and forming a new coupled vibration transmission path. It forms a coherent superposition of multi-source vibration with the rotor vibration transmission path, affecting the stealth performance of the vehicle.

[0004] From the above, it can be seen that suppressing the generation and development of the pump-jet rotor tip gap vortex is of great significance to improving the acoustic performance of the pump-jet propulsor. Some of the rotor tip gap vortex control methods that have been proposed, such as ring rotors, installing perforated guides in the duct, and blade tip air replenishment, have significantly increased the complexity, design burden and weight of the pump-jet structure, making it difficult to implement engineering applications. Summary of the invention

[0005] The purpose of the present invention is to provide a pump-jet rotor tip vortex control device based on a blade tip wing, which can not only effectively control the generation and development of tip vortex, but also effectively suppress the pressure pulsation and unsteady flow excitation caused by the tip vortex without almost increasing the structural complexity, design burden and weight of the pump-jet propulsor, thereby facilitating engineering applications.

[0006] The technical solution adopted by the present invention is:

[0007] A pump-jet rotor tip vortex control device based on a blade tip wing, under the premise that the open water performance of a pump-jet propulsor meets the rapidity requirements, a blade tip wing is additionally provided on the pressure surface side of the rotor blade tip position; the starting point at the leading edge wing root of the blade tip wing is arranged delayed relative to the leading edge of the rotor blade tip, and the trailing edge wing root is arranged forward relative to the trailing edge of the rotor blade tip; the leading edge of the blade tip wing is tilted backward and its line shape forms an angle with the rotor blade skeleton line, and the trailing edge is tilted forward and its line shape forms an angle with the rotor blade skeleton line; the frontal surface of the lower end face of the leading edge of the blade tip wing is a NACA airfoil leading edge type, and the upper end face of the blade tip wing keeps consistent with the line shape of the inner wall of the duct, and the clearance height keeps the same.

[0008] Preferably, the distance a between the starting point at the root of the leading edge of the blade tip and the leading edge of the rotor blade tip and the distance c between the root of the trailing edge of the blade tip and the trailing edge of the rotor blade tip are determined according to the size of the rotor blade tip and the flow state.

[0009] Preferably, the value range of a is 5% to 7% of the blade profile chord length of the rotor blade tip; the value range of c is 10% to 12% of the blade profile chord length of the rotor blade tip.

[0010] Preferably, the angle θ between the leading edge line of the blade tip wing and the rotor blade skeleton line is 20°~25°; the angle between the trailing edge line of the blade tip wing and the rotor blade skeleton line is 50°~80°.

[0011] Preferably, the wing width b of the blade tip wing is 80% to 100% of the thickness of the rotor blade tip.

[0012] Preferably, the blade tip wing is designed with equal thickness except for the leading edge transition section, and the thickness d of the blade tip wing is 80% to 90% of the thickness of the trailing edge of the rotor blade.

[0013] Preferably, the wing root where the tip wing is connected to the rotor blade tip is smoothly transitioned by chamfering.

[0014] The beneficial effects of the present invention are:

[0015] Compared with traditional tip vortex control devices, the device has a simple structure and convenient design. The weight of the rotor blades increases by no more than 2%, and the impact on the overall weight of the pump-jet is negligible. It does not affect the overall design of the underwater vehicle and almost does not increase the structural complexity, design burden and weight of the pump-jet propulsor. The tip vortex control effect of the device is outstanding. It can not only effectively control the generation and development of tip vortex, but also greatly reduce the pressure pulsation at the blade tip and the flow excitation to the duct, and basically eliminate the transmission of the duct flow-induced vibration caused by the tip vortex to the hull structure. That is, it can effectively suppress the pressure pulsation and unsteady flow excitation caused by the tip vortex, facilitate engineering applications, and provide technical support for low-noise pump-jet propulsors. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of a pump-jet propulsion system.

[0017] Figure 2 This is a comparison of the traditional rotor blades before and after adding the blade tip wing.

[0018] Figure 3 It is a partial top view of the position of the blade tip wing in an embodiment of the present invention.

[0019] Figure 4 It is a side view of the position of the blade tip wing in an embodiment of the present invention.

[0020] Figure 51 is a comparison diagram of the tip vortex structure represented by the Q value isosurface in the embodiment of the present invention, (a) is a rotor blade with an additional blade tip wing, and (b) is a traditional rotor blade.

[0021] Figure 6 2 is a comparison diagram of vortex strength at different cross sections in an embodiment of the present invention, (a) is a rotor blade with an additional blade tip wing, and (b) is a traditional rotor blade.

[0022] Figure 7 It is a comparison diagram of the pressure pulsation amplitude changes of the rotor blades with additional blade tip wings in the embodiment of the present invention and the traditional rotor blades.

[0023] Figure 8 It is a comparison diagram of the change in amplitude of the axial unsteady force of the duct of the rotor blade with the blade tip wing added in the embodiment of the present invention and the traditional rotor blade.

[0024] In the figure: 1-rotor; 2-duct; 3-stator; 4-rotor blade; 5-rotor hub; 6-blade tip wing; 7-blade tip wing trailing edge; 8-blade tip wing leading edge; A-boundary between blade tip wing and rotor blade; B-rotor blade skeleton line. DETAILED DESCRIPTION

[0025] A pump-jet rotor tip vortex control device based on a blade tip wing, under the premise that the open water performance of the pump-jet propulsor meets the rapidity requirements, such as Figure 2 As shown, a blade tip wing 6 is added on the pressure side of the blade tip of the rotor blade 4:

[0026] 1. Regarding the position and size design of the blade tip wing 6, Figures 2 to 4 As shown: the starting point at the root of the leading edge 8 of the blade tip wing 6 is arranged backward relative to the leading edge of the blade tip of the rotor blade 4, and the root of the trailing edge 7 is arranged forward relative to the trailing edge of the blade tip of the rotor blade 4. The distance a between the starting point at the root of the leading edge 8 of the blade tip wing and the leading edge of the blade tip of the rotor blade 4 and the distance c between the root of the trailing edge 7 of the blade tip of the blade tip and the trailing edge of the rotor blade 4 are determined according to the tip size and flow state of the rotor blade 4. Preferably, the value range of a is 5%~7% of the blade chord length of the blade tip of the rotor blade 4, and the value range of c is 10%~12% of the blade chord length of the blade tip of the rotor blade 4; the wing width b of the blade tip wing 6 is 80%~100% of the thickness of the blade tip of the rotor blade 4; the blade tip wing 6 is designed with equal thickness except the transition section of the leading edge 8, and the thickness d of the blade tip wing 6 is 80%~90% of the thickness of the trailing edge of the rotor blade 4.

[0027] 2. Regarding the airfoil design of the blade tip wing 6, Figures 2 to 4As shown: the leading edge 8 of the blade tip wing 6 is tilted backward and its line shape forms an angle with the rotor blade skeleton line B, and the trailing edge 7 is tilted forward and its line shape forms an angle with the rotor blade skeleton line B. In order to achieve the best tip vortex control and hydrodynamic effect, preferably, the angle θ between the line shape of the blade tip wing leading edge 8 and the rotor blade skeleton line B is 20°~25°, and the angle between the line shape of the blade tip wing trailing edge 7 and the rotor blade skeleton line B is 50°~80°; the flow surface of the lower end face of the blade tip wing leading edge 8 is a NACA airfoil leading edge type; the wing root where the blade tip wing 6 is connected to the rotor blade 4 is smoothly transitioned by chamfering.

[0028] 3. Regarding the relationship between the blade tip wing 6 and the duct 2: the line shape of the upper end surface of the blade tip wing 6 and the inner wall surface of the duct 2 are kept consistent, and the gap height is kept the same.

[0029] Compared with the traditional tip vortex control device, the present device has a simple structure and convenient design. The weight of the rotor blade 4 increases by no more than 2%, and the effect on the overall weight of the pump-jet is negligible. It does not affect the overall design of the underwater vehicle and almost does not increase the structural complexity, design burden and weight of the pump-jet propulsor.

[0030] After the conventional rotor blade 4 is equipped with the present device, Figure 5 As shown in FIG. 1 , the tip vortex structure is represented by the Q value isosurface. It can be seen that after the rotor blade 4 is equipped with the blade tip wing 6, the tip vortex is shortened by more than half, and as shown in FIG. Figure 6 As shown in FIG. 1 , the rotation intensity of the tip vortex at the same position along the chord length direction is significantly reduced; the middle area of ​​the tip clearance of the rotor blade 4 along the chord direction is the area where the tip vortex generates the most intense pressure pulsation. After the conventional rotor blade 4 is equipped with the present device, as shown in FIG. Figure 7 As shown in FIG. 4 , it can be seen that after the rotor blade 4 is provided with a blade tip wing 6, the first-order blade frequency amplitude of the pressure pulsation in the gap can be reduced by 81%, and as shown in FIG. Figure 8 As shown in the figure, the first-order blade frequency amplitude of the axial extraordinary force of duct 2 is reduced by 91%. As can be seen from the above, the tip vortex control effect of this device is outstanding. It can not only effectively control the generation and development of tip vortex, but also greatly reduce the pressure pulsation at the blade tip and the flow excitation to the duct, and basically eliminate the transmission of the duct flow-induced vibration caused by the tip vortex to the hull structure, that is, it can effectively suppress the pressure pulsation and unsteady flow excitation caused by the tip vortex, which is convenient for engineering application and provides technical support for low-noise pump-jet propulsion.

[0031] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A pump-jet rotor tip vortex control device based on a blade tip wing, characterized in that: On the premise that the open water performance of the pump-jet propulsor meets the rapidity requirements, a blade tip wing is added on the pressure surface side of the rotor blade tip position; the starting point at the leading edge root of the blade tip wing is arranged backward relative to the leading edge of the rotor blade tip, and the trailing edge root is arranged forward relative to the trailing edge of the rotor blade tip; the leading edge of the blade tip wing is tilted backward and the line shape forms an angle with the rotor blade bone line, the trailing edge is tilted forward and the line shape forms an angle with the rotor blade bone line, the frontal surface of the lower end face of the leading edge of the blade tip wing is a NACA airfoil leading edge type, the upper end face of the blade tip wing is consistent with the line shape of the inner wall of the duct, and the clearance height is maintained the same.

2. The pump-jet rotor tip vortex control device based on blade tip wing according to claim 1, characterized in that: The distance a between the starting point at the root of the leading edge of the blade tip and the leading edge of the rotor blade tip and the distance c between the root of the trailing edge of the blade tip and the trailing edge of the rotor blade tip are determined according to the size of the rotor blade tip and the flow state.

3. The pump-jet rotor tip vortex control device based on blade tip wing according to claim 2, characterized in that: The value range of a is 5%~7% of the blade chord length of the rotor blade tip; the value range of c is 10%~12% of the blade chord length of the rotor blade tip.

4. The pump-jet rotor tip vortex control device based on blade tip wing according to claim 1, characterized in that: The angle θ between the leading edge line of the blade tip wing and the rotor blade skeleton line is 20°~25°; the angle between the trailing edge line of the blade tip wing and the rotor blade skeleton line is 50°~80°.

5. The pump-jet rotor tip vortex control device based on blade tip wing according to claim 1, characterized in that: The wing width b of the blade tip wing is 80%~100% of the thickness of the rotor blade tip.

6. The pump-jet rotor tip vortex control device based on blade tip wing according to claim 1, characterized in that: The blade tip wing is designed with equal thickness except the leading edge transition section. The thickness d of the blade tip wing is 80%~90% of the thickness of the trailing edge of the rotor blade.

7. The pump-jet rotor tip vortex control device based on blade tip wing according to claim 1, characterized in that: The wing root where the tip wing is connected to the rotor blade tip is smoothly transitioned by chamfering.

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