Moving impeller blade surface configuration method for improving cavitation performance of water jet propulsion pump

Abstract

The invention belongs to the field of ship power systems, and discloses a moving impeller blade surface configuration method for improving cavitation performance of a water jet propulsion pump, which comprises the following steps of: unfolding airfoils at sections with different radiuses to a plane; dividing a movable impeller pressure surface blade section configuration optimization triangular region; and cutting off the section configuration optimization triangular area of the blade on the pressure surface of the movable impeller. By changing different radiuses which are profiles from the guide edges to the pressure surfaces of the blades, on the premise that the pump efficiency is not reduced, the pressure difference between the suction surface and the pressure surface of the movable impeller is further optimized, and the cavitation performance of the pump is improved.

Description

Technical Field

[0001] The invention belongs to the field of ship power systems and relates to a method for configuring the surface of a moving impeller blade for improving the cavitation performance of a water jet propulsion pump. Background Art

[0002] Waterjet propulsion is a special ship propulsion method that uses the momentum difference of the water flow ejected by the propulsion pump to propel the ship forward. The waterjet propulsion pump is the core hydrodynamic component of the waterjet propulsion device. Cavitation performance is one of the key indicators for evaluating waterjet propulsion pumps. Cavitation of waterjet propulsion pumps will lead to reduced thrust, power fluctuations, increased noise, and will cause surface metal erosion of the pump's impeller, guide vane body and flow channel. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for configuring the surface of an impeller blade for improving the cavitation performance of a water jet propulsion pump. The cavitation performance is further optimized by changing the airfoil structure of the cross-section from the leading edge of the impeller to the pressure surface of the blade, reducing the local airfoil thickness of the inlet area of ​​different radius sections, and reducing the surface pressure difference between the suction surface and the pressure surface.

[0004] In order to achieve the above object, the technical solution of the present invention is to provide a method for configuring the surface of a moving impeller blade for improving the cavitation performance of a water jet propulsion pump, comprising the following steps:

[0005] The airfoil is unfolded to a plane at each section with different radii;

[0006] Divide the impeller pressure surface blade section configuration optimization triangle area;

[0007] The blade section configuration of the impeller pressure surface is optimized by cutting away a triangular region.

[0008] According to the present invention, further, the configuration method is implemented on the pressure surface side of the impeller blade.

[0009] According to the present invention, further, the airfoil at each cross section of different radius is unfolded to a plane including a chord length h, a pressure surface p and a suction surface q connected end to end with the pressure surface p to form a closed figure, thereby obtaining an airfoil with transformed thickness, camber and chord length.

[0010] According to the present invention, further, the division of the impeller pressure surface blade section configuration optimization triangular area includes:

[0011] Divide the impeller from the hub to the blade tip into 20 airfoil sections;

[0012] The optimized area of ​​the pressure side blade profile configuration is constructed from 10 profiles from the tip to the middle of the blade.

[0013] According to the present invention, further, the cross section constructed from the blade tip to the middle of the blade is composed of a curve at the blade tip, a curve at the pressure surface and a curve at the guide edge fillet.

[0014] According to the present invention, further, the length of the curve of the blade tip is 45% of the chord length h.

[0015] According to the present invention, further, the method for obtaining the curve of the pressure surface is to make pressure surface airfoil tangents for the 20 divided airfoil sections from the tip of the blade toward the hub; wherein the percentage of the end point of the pressure surface airfoil tangent to the airfoil chord length at that location is: the end point of the tangent at the i-th section is the position of (45% - (i-1) * 5%) of the airfoil chord length of the section, wherein i is an integer greater than 0, and after completion, the end points of the pressure surface airfoil tangents of each section are connected by a spline curve.

[0016] According to the present invention, further, a method for obtaining the curve at the guide edge fillet is as follows: the curve at the guide edge fillet is evenly divided into 20 equal parts, the starting point of the tangent line of the airfoil of the i-th section pressure surface is at a distance from the midpoint of the arc by (i-1)*5% of the arc length, and i is an integer greater than 0.

[0017] According to the present invention, further, the curve at the tip of the blade, the curve at the pressure surface and the curve at the guide edge fillet are connected to form a curved surface, and the initial blade is divided by the curved surface to form a complete impeller pressure surface cut-off area, and the area is cut off to form an impeller blade that improves the cavitation performance of the water jet propulsion pump.

[0018] According to the present invention, it is further applied to the processing field of conventional axial-flow water jet pumps and mixed-flow water jet pumps.

[0019] The beneficial effects of the present invention are:

[0020] By changing the airfoil with different radii from the guide edge to the pressure surface of the blade, the pressure difference between the suction surface and the pressure surface of the impeller can be further optimized without reducing the pump efficiency, thereby improving the cavitation performance of the pump.

[0021] The present invention can improve the cavitation performance of a water jet propulsion pump, reduce the weight of the device, and reduce vibration and noise.

[0022] The invention is aimed at the impellers of axial-flow water jet pumps and mixed-flow water jet pumps, and is applicable to conventional axial-flow water jet pumps and mixed-flow water jet pumps. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the airfoil arrangement and structure of the impeller of the propeller of the present invention;

[0024] Figure 2 It is a schematic plan view of an airfoil that completes the transformation of thickness, camber and chord length of the present invention;

[0025] Figure 3 It is a schematic diagram of the optimized area of ​​the airfoil of the pressure surface section of the impeller blade of the present invention;

[0026] Figure 4 It is a schematic diagram of the tangent line of the pressure surface airfoil of the present invention;

[0027] Figure 5 It is a schematic diagram of the connection line of the pressure surface airfoil tangent line along the inlet edge of the present invention;

[0028] Figure 6 It is a reference schematic diagram of the complete impeller pressure surface cut-out area of ​​the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0030] The present application discloses a method for improving the cavitation performance of a water jet pump impeller blade surface configuration, see Figure 1 , is a schematic diagram of the airfoil arrangement and composition of the impeller of the propeller. The impeller of a water jet propulsion pump usually has 4-6 blades, and each blade is composed of airfoils at different radius sections. The airfoils on different sections have different chord lengths, thicknesses, cambers and placement angles. In order to improve the cavitation performance of the water jet propulsion pump and change the pressure difference between the suction surface and the pressure surface of the impeller, it is necessary to cut off the pressure surface area of ​​each impeller. Among them, the configuration changes of each airfoil section of the impeller of the water jet propulsion pump are implemented on the pressure side of the blade; the impeller configuration implementation starts from the triangular area from the middle area of ​​the blade to the tip of the blade.

[0031] Specifically, see Figure 2 , which is a plan schematic diagram of the airfoil with thickness, camber and chord length transformed; the airfoil of a certain section is unfolded to a plane, and the plane figure includes the chord length h, the pressure surface p and the suction surface q connected to the pressure surface p end to end to form a closed figure as shown in the figure, and the airfoil with thickness, camber and chord length transformed can be obtained.

[0032] See also Figure 3 , is a schematic diagram of the optimized airfoil area of ​​the impeller blade pressure surface section;

[0033] Divide the impeller pressure surface blade section configuration optimization triangle area:

[0034] The impeller is divided into 20 airfoil sections from the hub to the blade tip. The construction of the pressure surface blade section configuration optimization area involves 10 sections from the blade tip to the middle of the blade, which are respectively composed of curve 1 at the blade tip, curve 2 at the pressure surface, and curve 3 at the guide edge fillet; the length of curve 1 at the blade tip is 45% of the chord length h;

[0035] See also Figure 4 , is a schematic diagram of the tangent line of the airfoil on the pressure surface;

[0036] Among them, the method of obtaining curve 2 of the pressure surface is similarly to that from the tip of the blade to the hub. Figure 3 Each airfoil section in Figure 4 The method shown is used to make the pressure surface airfoil tangent; wherein, the percentage of the pressure surface airfoil tangent end point to the airfoil chord length at that location is as follows: the tangent end point at the i-th section is at the position of (45% - (i-1) * 5%) of the airfoil chord length of that section, wherein i is an integer greater than 0. After calculation, the end points of the pressure surface airfoil tangents of each section are connected by a spline curve to obtain Curve 2.

[0037] How to obtain curve 3 at the edge fillet: It is the connecting curve of the starting points of the airfoil tangents on each pressure surface. Figure 5 , is a schematic diagram of the pressure surface airfoil tangent line along the inlet edge. The curve 3 at the guide edge fillet is evenly divided into 20 equal parts. The distance from the starting point of the pressure surface airfoil tangent of the i-th section to the midpoint of the arc is (i-1)*5% of the arc length.

[0038] See also Figure 6 , which is a reference schematic diagram of the complete impeller pressure surface cut-out area. Curve 1 at the blade tip, curve 2 at the pressure surface and curve 3 at the guide edge fillet are connected to form a curved surface. The initial blade is divided by the curved surface to form a complete impeller pressure surface cut-out area, and the area is cut off to finally form an impeller blade that can improve the cavitation performance of the water jet propulsion pump.

[0039] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for configuring the surface of a moving impeller blade for improving the cavitation performance of a water jet pump, characterized in that: The steps include: The airfoil is unfolded to a plane at each section with different radii; Divide the impeller pressure surface blade section configuration optimization triangle area; The blade section configuration of the impeller pressure surface is optimized by cutting away a triangular region.

2. A method for configuring the surface of an impeller blade for improving the cavitation performance of a water jet pump according to claim 1, characterized in that: The configuration method is implemented on the pressure surface side of the impeller blade.

3. A method for configuring the surface of an impeller blade for improving the cavitation performance of a water jet pump according to claim 1, characterized in that: The airfoil at each section with different radii is unfolded to a plane including a chord length h, a pressure surface p and a suction surface q connected end to end with the pressure surface p to form a closed figure, thereby obtaining an airfoil with changed thickness, camber and chord length.

4. A method for configuring the surface of an impeller blade for improving the cavitation performance of a water jet pump as claimed in claim 1, characterized in that: The dividing of the impeller pressure surface blade section configuration optimization triangular area comprises: dividing the impeller from the hub to the blade tip into 20 airfoil sections; The optimized area of ​​the pressure side blade profile configuration is constructed from 10 profiles from the tip to the middle of the blade.

5. A method for configuring the surface of an impeller blade for improving the cavitation performance of a water jet pump as claimed in claim 4, characterized in that: The cross section constructed from the blade tip to the middle of the blade is composed of a curve at the blade tip, a curve at the pressure surface, and a curve at the guide edge fillet.

6. A method for configuring the surface of impeller blades for improving the cavitation performance of a water jet pump as claimed in claim 5, characterized in that: The length of the curve of the blade tip is 45% of the chord length h.

7. A method for configuring the surface of a moving impeller blade for improving the cavitation performance of a water jet pump as claimed in claim 4, characterized in that: The method for obtaining the curve of the pressure surface is as follows: 20 divided airfoil sections are made into pressure surface airfoil tangents from the tip of the blade toward the hub; wherein the percentage of the airfoil chord length at the pressure surface tangent end point is: the tangent end point at the i-th section is the position of (45%-(i-1)*5%) of the airfoil chord length of the section, wherein i is an integer greater than 0, and after completion, the end points of the pressure surface airfoil tangents of each section are connected by a spline curve.

8. A method for configuring the surface of a moving impeller blade for improving the cavitation performance of a water jet pump as claimed in claim 7, characterized in that: The method for obtaining the curve at the guide edge fillet is as follows: the curve at the guide edge fillet is evenly divided into 20 equal parts, the starting point of the tangent line of the airfoil of the i-th section pressure surface is at a distance from the midpoint of the arc by (i-1)*5% of the arc length, and i is an integer greater than 0.

9. A method for configuring the surface of impeller blades for improving the cavitation performance of a water jet pump as claimed in claim 8, characterized in that: The curve at the tip of the blade, the curve at the pressure surface and the curve at the guide edge fillet are connected to form a curved surface, which is used to divide the initial blade to form a complete impeller pressure surface cut-out area, and the area is cut out to form an impeller blade that improves the cavitation performance of the water jet propulsion pump.

10. A method for configuring the surface of impeller blades for improving the cavitation performance of a water jet pump as claimed in claim 9, characterized in that: Applicable to the processing fields of conventional axial-flow water jet pumps and mixed-flow water jet pumps.

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