A drag reduction method for impeller blades with bionic fish scale structure

Abstract

The present invention discloses a drag reduction method for an impeller blade of a bionic fish scale structure, comprising the following steps: S1, obtaining a fish scale sample, selecting a fish scale with a standard appearance from the fish scale sample; S2, collecting the coordinate points of the outer contour of the fish scale, fitting and correcting the collected coordinate points to obtain a scale body curve; S3, arranging the scale body obtained in step S2 in a predetermined arrangement in the drag reduction area of ​​the airfoil body, and performing three-dimensional modeling to obtain the impeller blade. The present invention effectively reduces the airfoil surface resistance by arranging the scale body at intervals on the airfoil body surface, greatly improving its drag reduction performance, especially under low flow rate conditions, the drag reduction effect is very remarkable, greatly reducing the friction resistance between the wall and the fluid, achieving a significant improvement in the drag reduction characteristics, the airfoil surface shear stress is evenly distributed, the friction resistance is evenly distributed, the stress concentration problem is solved, and the phenomenon of hydraulic machinery blades being damaged due to stress concentration is effectively improved.

Description

Technical Field

[0001] The invention relates to the field of fluid machinery, and in particular to a drag reduction method for impeller blades with a bionic fish scale structure. Background Art

[0002] As the basic structure in the field of fluid machinery, airfoils have a wide range of applications, including wings in the aviation field, propeller airfoils, wind turbine blade cross-section airfoils, etc. With the rapid development of science and the fluid machinery industry, especially with the expansion of application fields, such as tidal power generation, marine water jets, underwater vehicles, and various pump blades, people are no longer satisfied with the dynamic performance provided by traditional airfoils, and the requirements for airfoil performance are getting higher and higher. Various industries have higher and higher requirements for the drag reduction performance of traditional blades, so it is particularly important to develop blades with excellent drag reduction performance. Summary of the invention

[0003] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a drag reduction method for impeller blades with a bionic fish scale structure; the present invention obtains an impeller blade that can produce effective drag reduction performance through bionics.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A drag reduction method for an impeller blade with a bionic fish scale structure comprises the following steps:

[0006] S1. Obtain fish scale samples, and select fish scales with standard appearance from the fish scale samples;

[0007] S2, collecting the coordinate points of the outer contour of the fish scale, fitting and correcting the collected coordinate points to obtain the scale body curve;

[0008] S3, arranging the scale bodies obtained in step S2 in a predetermined arrangement in the drag reduction area of ​​the airfoil body, and performing three-dimensional modeling to obtain impeller blades.

[0009] As a further solution of the present invention: the outer contour of the scale body includes:

[0010] The first base segment is located at the front end of the scale body;

[0011] The second base segment and the fourth base segment are respectively connected to two ends of the first base segment and are symmetrically arranged relative to the first base segment;

[0012] The third base segment is located at the rear end of the scale body, and its two ends are connected to the second base segment and the fourth base segment respectively;

[0013] The first base segment, the second base segment, the third base segment and the fourth base segment are all in arc shape;

[0014] The arc openings of the first base segment and the third base segment are arranged opposite to each other, and the arc openings of the second base segment and the fourth base segment are arranged opposite to each other.

[0015] As a further solution of the present invention: the curve function of the first base segment is:

[0016]

[0017] Where 4.699≤a≤4.772;

[0018] -0.688≤b≤-0.756;

[0019] 0.0355≤c≤0.385;

[0020] 0.669≤d≤0.689;

[0021] The curve function of the second base segment is:

[0022]

[0023] Where 1.899≤e≤2.012;

[0024] -0.021≤f≤-0.011;

[0025] -0.9927≤g≤-0.7622;

[0026] -3.001≤h≤-2.788;

[0027] The curve function of the third base segment is:

[0028]

[0029] Where 0.779≤i≤0.989;

[0030] -0.544≤j≤-0.416;

[0031] The curve function of the fourth base segment is:

[0032]

[0033] Among them, 9527≤k≤9677;

[0034] -33.66≤m≤-33.15;

[0035] 0.1869≤n≤0.1983;

[0036] -0.858≤o≤-0.698.

[0037] As a further solution of the present invention: the length of the scale body is δ1, the width is δ2, the length of the first base segment is δ3,

[0038]

[0039]

[0040] 5.496mm≤δ2≤6.334mm.

[0041] As a further solution of the present invention: the thickness of the scale body is between 0.377 mm and 0.642 mm.

[0042] As a further solution of the present invention: drag reduction areas are arranged at intervals on the airfoil body of the drag reduction blade along the chord length direction, the scale bodies are evenly arranged in the drag reduction areas of the airfoil body, and the front end of the scale body faces the rear end of the airfoil body, and the rear end of the scale body faces the front end of the airfoil body.

[0043] As a further solution of the present invention: two groups of drag reduction areas are arranged at intervals along the chord length direction on the airfoil body, at least two rows of scale bodies are arranged in the two drag reduction areas, and the positions of two adjacent rows of scale bodies are staggered along the chord length direction.

[0044] As a further solution of the present invention: the chord length of the airfoil body is 56 mm, the span is 20 mm, the distance between two adjacent rows of scale bodies in each drag reduction zone is not less than 3 mm, and the distance between the scale bodies in each row is not less than 4 mm; the distance between the drag reduction zone close to the tail end of the airfoil body and the tail end of the airfoil is 2 mm to 9 mm, and the spacing between the two drag reduction zones is 12 mm to 15.5 mm.

[0045] As a further solution of the present invention: the airfoil body is a Clark-y airfoil.

[0046] As a further solution of the present invention: in step S3, the scale body is optimized on each reference plane through solid stretching and material removal functions during the modeling process.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The present invention effectively reduces the surface resistance of the airfoil by arranging the scale bodies at intervals on the surface of the airfoil body, greatly improving its drag reduction performance, especially under low flow rate conditions, the drag reduction effect is very remarkable, greatly reducing the friction resistance between the wall and the fluid, achieving a significant improvement in the drag reduction characteristics, the shear stress distribution on the airfoil surface is even, the friction resistance distribution is even, the stress concentration problem is solved, and the phenomenon of hydraulic machinery blades being damaged due to stress concentration is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the structure of the drag reduction blade in the present invention.

[0050] Figure 2 It is a schematic diagram of the structure of the scale body in the present invention.

[0051] Figure 3 This is the wall shear stress distribution diagram of the conventional Clark-y airfoil.

[0052] Figure 4 This is the wall shear stress distribution diagram of the drag reduction blade of the present invention.

[0053] In the figure: 1. Airfoil body; 2. Scale body;

[0054] 21. First base segment; 22. Second base segment; 23. Third base segment; 24. Fourth base segment. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] See also Figures 1 to 4 In an embodiment of the present invention, a drag reduction method for an impeller blade with a bionic fish scale structure includes an airfoil body 1, wherein the airfoil body 1 is preferably a Clark-y airfoil, wherein the chord length of the airfoil body 1 is 56 mm and the span thereof is 20 mm.

[0057] The airfoil body 1 is provided with the following Figure 1 The two groups of drag reduction areas are shown in Figure 1. The two groups of drag reduction areas have the same size, and their length is preferably 13 mm, and their width is equal to the span of the airfoil body 1, which is 20 mm.

[0058] The distance between one group of drag reduction areas and the tail end of the airfoil is 2 mm to 9 mm, preferably 3 mm. The distance between the two groups of drag reduction areas is 12 to 15.5 mm, preferably 13 mm.

[0059] Multiple rows of scale bodies 2 are evenly arranged in the two groups of drag reduction areas along the chord length direction of the airfoil body 1, preferably five rows. The distance between two adjacent rows of scale bodies 2 is not less than 4 mm, preferably 4.2 mm; the distance between the scale bodies 2 in each row is not less than 3 mm, preferably 3.3 mm. The positions of the two adjacent rows of scale bodies 2 in the drag reduction area along the chord length direction of the airfoil body 1 are staggered, and along the chord length direction, the rear row of scales is located on the midline of the line connecting the two adjacent groups of scales in the front row.

[0060] The front ends of the scale bodies 2 in the two groups of drag reduction areas are all toward the tail end of the airfoil body 1, and the rear ends of the scale bodies 2 are toward the front end of the airfoil body 1. When the scale bodies 2 are arranged on the airfoil body 1, their thickness is between 0.377 mm and 0.642 mm, preferably 0.5 mm.

[0061] The scale body 2 includes a first base segment 21, a second base segment 22, a third base segment 23 and a fourth base segment 24 which are sequentially connected in a clockwise direction and form a closed loop. The first base segment 21 is located at the front end of the scale body 2, the third base segment 23 is located at the rear end of the scale body 2, and the second base segment 22 and the fourth base segment 24 are symmetrically arranged about the first base segment 21 or the third base segment 23.

[0062] The first base segment 21 , the second base segment 22 , the third base segment 23 and the fourth base segment 24 are all in arc shape. The arc openings of the first base segment 21 and the third base segment 23 are arranged opposite to each other, and the arc openings of the second base segment 22 and the fourth base segment 24 are arranged opposite to each other.

[0063] The curve function of the first base segment 21 is:

[0064]

[0065] Where 4.699≤a≤4.772;

[0066] -0.688≤b≤-0.756;

[0067] 0.0355≤c≤0.385;

[0068] 0.669≤d≤0.689.

[0069] The curve function of the second base segment 22 is:

[0070]

[0071] Where 1.899≤e≤2.012;

[0072] -0.021≤f≤-0.011;

[0073] -0.9927≤g≤-0.7622;

[0074] -3.001≤h≤-2.788.

[0075] The curve function of the third base segment 23 is:

[0076]

[0077] Where 0.779≤i≤0.989;

[0078] -0.544≤j≤-0.416.

[0079] The curve function of the fourth base segment 24 is:

[0080]

[0081] Among them, 9527≤k≤9677;

[0082] -33.66≤m≤-33.15;

[0083] 0.1869≤n≤0.1983;

[0084] -0.858≤o≤-0.698.

[0085] The length of the scale body 2 is δ1, the width is δ2, and the length of the first base section 21 is δ3.

[0086]

[0087]

[0088] 5.496mm≤δ2≤6.334mm.

[0089] In the preferred embodiment, δ2=6mm, δ1=6.9906mm, and δ3=2.8266mm.

[0090] When designing impeller blades, the following steps are involved:

[0091] S1. Obtain fish scale samples, and select fish scales with standard appearance from the fish scale samples;

[0092] There are no less than one hundred groups of fish scale samples, and after multiple batches of screening, the most standard group of fish scales is obtained.

[0093] S2. Collect the outer contour coordinate points of the fish scale with the most standard appearance in step S1, obtain the outer contour curve of the scale body 2 by fitting the collected coordinate points through MATLAB, and correct the outer contour curve through a multi-parameter exponential function to obtain the curve of the scale body 2 after correction.

[0094] S3, arranging the scale body 2 obtained in step S2 in the drag reduction area of ​​the airfoil body 1 in a predetermined arrangement, performing three-dimensional modeling through PROE to obtain the drag reduction blade, and optimizing the scale body 2 on each reference plane through solid stretching and material removal functions during the modeling process.

[0095] Considering that the general swimming speed of fish in water is 0.8m / s~1.2m / s, three low flow velocities of 0.8m / s, 1.0m / s and 1.2m / s are taken. In addition, a medium flow velocity of 5.6m / s and a high flow velocity of 10m / s are taken. FLUENT simulation is carried out on the conventional Clark-y airfoil and the Clark-y airfoil with spaced scale bodies 2 under five flow velocity conditions, and the resistance is calculated.

[0096] The results are shown in the table below. Through the analysis of the results, it can be seen that the Clark-y airfoil with the scale body 2 arranged at intervals under various working conditions has a drag reduction effect compared with the conventional Clark-y airfoil, especially under low flow conditions. The drag reduction effect is very remarkable, and the drag reduction rate can reach 50% at a flow rate of 1.0 m / s.

[0097]

[0098] like Figure 3 As shown, at a flow rate of 1 m / s, the conventional Clark-y airfoil has a higher wall shear stress and a larger friction resistance between the wall and the fluid.

[0099] like Figure 4 As shown, at the same flow rate of 1 m / s, the shear stress distribution of the Clark-y airfoil wall with the scale body 2 arranged at intervals is uniform, and the friction resistance distribution is also more even, which greatly improves the stress concentration, thereby effectively improving the phenomenon of damage to the hydraulic machinery blades due to stress concentration, and the drag reduction rate reaches 52.5%.

[0100] According to FLUENT simulation, when the surface of the Clark-y airfoil is fully covered with the scale body 2, the drag reduction rate of the Clark-y airfoil with the scale bodies 2 arranged at intervals is still higher than that of the Clark-y airfoil with the scale bodies 2 fully covered. Therefore, the interval arrangement scheme of the scale bodies 2 of the present invention enables the hydraulic performance of the blade to reach the best under low flow conditions.

[0101] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0102] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0103] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0104] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0105] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. An impeller blade with a bionic fish scale structure, characterized in that: Two groups of drag reduction areas are arranged at intervals on the airfoil body (1) of the impeller blade along the chord length direction, at least two rows of scale bodies (2) are arranged in the two drag reduction areas, and the positions of two adjacent rows of scale bodies (2) are staggered along the chord length direction; the front end of the scale body (2) faces the rear end of the airfoil body (1), and the rear end of the scale body (2) faces the front end of the airfoil body (1); The outer contour of the scale body (2) includes: A first base section (21) is located at the front end of the scale body (2); The second base segment (22) and the fourth base segment (24) are respectively connected to two ends of the first base segment (21) and are symmetrically arranged relative to the first base segment (21); The third base segment (23) is located at the rear end of the scale body (2), and its two ends are respectively connected to the second base segment (22) and the fourth base segment (24); The first base segment (21), the second base segment (22), the third base segment (23) and the fourth base segment (24) are all in an arc shape; The arc openings of the first base segment (21) and the third base segment (23) are arranged opposite to each other, and the arc openings of the second base segment (22) and the fourth base segment (24) are arranged opposite to each other; The curve function of the first base segment (21) is: Where 4.699≤a≤4.772; 0.688≤b≤0.756； 0.0355≤c≤0.385； 0.669≤d≤0.689； The curve function of the second base segment (22) is: Where 1.899≤e≤2.012; -0.021≤f≤-0.011； -0.9927≤g≤-0.7622； -3.001≤h≤-2.788； The curve function of the third base segment (23) is: Where 0.779≤i≤0.989; -0.544≤j≤-0.416； The curve function of the fourth base segment (24) is: Among them, 9527≤k≤9677; -33.66≤m≤-33.15； 0.1869≤n≤0.1983； -0.858≤o≤-0.698。 2. The impeller blade with a bionic fish scale structure according to claim 1, characterized in that: The thickness of the scale body (2) is between 0.377 mm and 0.642 mm.

3. The impeller blade with a bionic fish scale structure according to claim 1, characterized in that: The chord length of the airfoil body (1) is 56 mm, the span is 20 mm, the distance between two adjacent rows of scale bodies (2) in each drag reduction zone is not less than 3 mm, and the distance between the scale bodies (2) in each row is not less than 4 mm; the distance between the drag reduction zone close to the tail end of the airfoil body (1) and the tail end of the airfoil is 2 mm to 9 mm, and the distance between the two drag reduction zones is 12 mm to 15.5 mm.

4. The impeller blade with a bionic fish scale structure according to claim 1, characterized in that: The airfoil body (1) is a Clark-y airfoil.

Images