A semi-open centrifugal impeller with splitter blades

Abstract

The present invention belongs to the technical field of gas turbines, and specifically relates to a semi-open centrifugal impeller with splitter blades, including a hub, main blades, and splitter blades. The hub is convex, and a concave arc-shaped transition section is provided on the hub. The main blades and splitter blades are evenly distributed on the arc-shaped transition section and are reinforced and connected to the hub through the blade root fillet. The rear end face of the hub is arc-shaped, and the dynamic balance counterweight hole and the dynamic balance deweighting belt are respectively arranged on the upper and lower end faces of the hub, and the dynamic balance effect is good. The present invention adopts the main blades and splitter blades to be evenly distributed alternately on the arc-shaped hub, and the structural strength is high. The main blades and splitter blades can pressurize the incoming gas in turn, and the total gas pressure efficiency is high, the pressure ratio is high, and the uniformity of airflow pressure is good, which ensures that the impeller can rotate stably at high speed, the vibration of the impeller is reduced, the centering ability of the impeller is enhanced, the noise is reduced, the durability is enhanced, and a relatively long and stable service life is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of gas turbines, relates to an impeller mechanical device, and in particular to a semi-open centrifugal impeller with splitter blades. Background Art

[0002] In the contemporary industrial field, compressors and other rotating machinery are widely used. In the chemical, mining, medical, energy and military fields, a large number of efficient compressors are needed to provide compressed air or other compressed gases. The compressor is a component in a gas turbine engine that uses high-speed rotating blades to work on the air to increase the air pressure. In order to reduce the impact loss of the air flow, the kinetic energy obtained by the gas in the impeller is converted into pressure as much as possible. The compression ratio reflects the degree of compression of the flow by the compressor. Increasing the compression ratio of the engine can improve the compression efficiency and combustion efficiency. The supercharging process will cause the total pressure loss of the engine. The supercharging ratio with a total pressure loss close to 0 is called the optimal supercharging ratio. At the optimal supercharging ratio, the engine has the maximum thrust, and at the most economical supercharging ratio, the engine has the lowest fuel consumption.

[0003] As the core component of the compressor, the design of the impeller is particularly important. At present, although the single-stage compression ratio of centrifugal compressors in the world is relatively high, the efficiency is relatively low, only about 79%, and the total pressure loss rate is relatively large. Generally, the compression ratio of widely used compressors is generally lower than 2.5, and the efficiency is lower than 82%. Therefore, designing a new energy-saving and efficient centrifugal compressor impeller is an important breakthrough in the design of rotating machinery; in addition, the impeller of the existing compressor has a low service life under ultra-high-speed rotation, low structural strength, easy deformation, poor resonance damping, resulting in large wind noise, resulting in poor durability and stability of the impeller. Summary of the invention

[0004] The invention provides a semi-open centrifugal impeller with splitter blades, aiming to improve the pressure increase ratio and total pressure efficiency of the impeller, strengthen the resonance damping of the impeller, and enhance the durability and stability of the impeller.

[0005] To achieve the purpose of the present invention, the present invention provides a semi-open centrifugal impeller with splitter blades, which is characterized in that it includes a hub, main blades, splitter blades, blade root fillets, dynamic balancing weight holes and dynamic balancing weight-removing belts; the main blades also include a main straight leading edge, a main bent wing, a main arc guide wing, a main side wing and a main upright straight trailing edge, and the main blades are used to increase the inlet flow capacity and the workmanship of the impeller; the splitter blades also include a secondary straight leading edge, a small bent wing, a secondary arc guide wing, a secondary side wing and a secondary upright straight trailing edge, and the splitter blades are used to enhance the workmanship of the impeller; the hub is convex, and a concave arc-shaped transition section is provided on the hub, the main blades and the splitter blades are evenly distributed on the arc-shaped transition section and are reinforced and connected to the hub through the blade root fillet, the rear end face of the hub is arc-shaped, and the dynamic balancing weight holes and the dynamic balancing weight-removing belt are respectively arranged on the upper and lower end faces of the hub to enhance the structural strength.

[0006] Furthermore, the main straight leading edge is at the outermost end of the main bent wing and close to the air inlet side of the upper end of the hub. The main bent wing is bent in the opposite direction to the rotation direction of the impeller. The main bent wing is smoothly connected to the main side wing through the main arc guide wing. A main vertical straight trailing edge is arranged on the outside of the main side wing. The main vertical straight trailing edge and the cylindrical surface of the hub are on the same arc surface and are parallel to the meridian flow surface.

[0007] Furthermore, the angle α1 between the main straight leading edge and the horizontal line of the meridian flow surface is 81.56 degrees.

[0008] Furthermore, the secondary straight leading edge is arranged at the upper end of the small curved wing, the small curved wing is smoothly transitionally connected to the secondary side wing through the secondary arc guide wing, and a secondary straight trailing edge is arranged at the lower end of the secondary side wing.

[0009] Furthermore, the angle α2 between the secondary straight leading edge and the horizontal line of the meridian flow surface is 74.67 degrees.

[0010] Furthermore, the blade leading edge line attack angle β1 of the main straight leading edge of the main blade and the secondary straight leading edge of the splitter blade are both 0 degrees.

[0011] Furthermore, the shapes of the main arc wing, main side wing and main upright trailing edge after being connected are exactly the same as those of the secondary arc wing, secondary side wing and secondary upright trailing edge after being connected, and the main upright trailing edge and the secondary upright trailing edge are parallel to the meridian flow plane.

[0012] Furthermore, the main wing and the main upright trailing edge have the same shape as the secondary wing and the secondary upright trailing edge, and the rearward bending angle β2 formed by each of them is 58 degrees.

[0013] Furthermore, the starting point of the secondary straight leading edge of the splitter blade is located behind the starting point of the main straight leading edge of the main blade and at about 12% of the length of the main blade along the meridian flow surface, that is, the length of the splitter blade is about 88% of the length of the main blade.

[0014] Furthermore, the number of the main blades and the splitter blades are both 13 and are evenly distributed on the arc-shaped transition section with intervals between each other. The thickness of the main straight leading edge and the secondary straight leading edge are both about 0.6 mm and have an arc-shaped transition. The thickness of the main vertical trailing edge and the secondary vertical trailing edge is about 6 mm, and the blade root fillet is R5.

[0015] The beneficial effects of the present invention are as follows: the present invention adopts a double-sided dynamic balancing experiment, places an additional counterweight screw in the counterweight hole at the front end of the hub to balance the front end imbalance, and uses cutting and other methods to remove material from the de-weighting belt on the back of the hub to eliminate the imbalance, thereby ensuring that the impeller can rotate stably at high speed. At the same time, the main blades and the diverter blades are alternately and evenly distributed on the arc-shaped hub, and the structural strength is high, which ensures the extremely high structural strength of the impeller; moreover, the main blades and the diverter blades can pressurize the incoming gas in turn, and the total gas pressure efficiency is high, achieving a maximum rotor efficiency of more than 95% and a compression ratio of more than 2.7, and the uniformity of the airflow pressurization is good, so that the impeller rotates with high roundness accuracy under ultra-high speed rotation, the vibration of the impeller is reduced, the centering ability of the impeller is enhanced, the noise is reduced, and the durability is enhanced, thereby ensuring a relatively long and stable service life. The impeller of the present invention is at the top level worldwide. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention;

[0017] Figure 2 It is a partial schematic diagram of the main blade and the splitter blade of the present invention;

[0018] Figure 3 It is a schematic diagram of the top view of the structure of the present invention;

[0019] Figure 4 It is a partial half-section schematic diagram of the present invention;

[0020] In the figure: 1 hub, 11 arc-shaped transition section, 2 main blades, 21 main straight leading edge, 22 main bent wing, 23 main arc guide wing, 24 main side wing, 25 main upright trailing edge, 3 splitter blades, 31 secondary straight leading edge, 32 small bent wing, 33 secondary arc guide wing, 34 secondary side wing, 35 secondary upright trailing edge, 4 blade root fillet, 5 dynamic balancing weight hole, 6 dynamic balancing weight removal belt, 7 shaft hole. DETAILED DESCRIPTION

[0021] Below, the present invention will be further described in conjunction with the accompanying drawings:

[0022] As shown in the accompanying drawings, a semi-open centrifugal impeller with splitter blades disclosed in the present invention comprises a hub 1, main blades 2, splitter blades 3, blade root fillets 4, dynamic balancing weight holes 5 and dynamic balancing weight-removing belts 6; wherein the hub 1, main blades 2, splitter blades 3, blade root fillets 4, dynamic balancing weight holes 5 and dynamic balancing weight-removing belts 6 are integrally formed, and are formed in one step by five-axis machining according to a three-dimensional solid model. The impeller material should be a metal material with a material performance not lower than 34CrNiMo, and the surface is carburized after machining and shaping. The hub 1 is convex, and a concave arc-shaped transition section 11 may be provided on the hub 1. The main blades 2 and the splitter blades 3 are evenly distributed on the arc-shaped transition section 11 and are reinforced and connected to the hub 1 through the blade root fillet 4. The blade root fillet 4 is a large arc chamfer for weight reduction. The rear end face of the hub 1 is arc-shaped. An annular dynamic balancing deweighting belt 6 is provided at a position more than half of the impeller radius behind the hub 1. The dynamic balancing deweighting belt 6 is provided at the highest point of the arc-shaped rear end face of the hub 1, such as Figure 4 As shown, the annular raised dynamic balancing weight-removing belt 6 is used to enhance the structural strength and ensure the stability of the dynamic balance of the impeller rotation. The width of the balancing weight-removing belt is 15~30mm, and the raised height is 3~10mm. The upper end surface of the hub 1 is provided with a dynamic balancing weight hole 5, which is a threaded hole for weight-adding and balancing. The dynamic balancing weight hole 5 at the front end of the hub 1 can be selected near a certain radius ring surface of the outer circle, and 18~36 threaded holes are set, with a hole diameter of M4~M12 and a hole depth of 20~40mm. Screw weight blocks can be placed for dynamic balancing. When doing dynamic balancing, a double-sided dynamic balancing experiment should be used. An additional weight screw is placed in the front end weight hole of the hub 1 to balance the front end imbalance. The back weight-removing belt of the hub 1 is cut to remove materials to eliminate the imbalance. According to the requirements of the transmission shaft, it can be designed as a 1:50 hydraulic interference cone shaft, or an end face tie rod structure, etc. The specific installation structure does not belong to the scope of protection of this patent. The impeller speed should be 14400 rpm. Solutions within the range of -20% and +10% of the rated speed (11520 rpm to 15840 rpm) are applicable to the impeller involved in this patent.

[0023] The main blade 2 also includes a main straight leading edge 21, a main curved wing 22, a main arc guide wing 23, a main side wing 24 and a main upright trailing edge 25. The main blade 2 is used to increase the inlet flow capacity and the workmanship of the impeller; the main straight leading edge 21 is at the outermost end of the main curved wing 22 and close to the air intake side of the upper end of the hub 1. The main curved wing 22 is bent in the opposite direction of the rotation direction of the impeller. The main curved wing 22 is smoothly connected to the main side wing 24 through the main arc guide wing 23. The main side wing 24 is provided with a main upright trailing edge 25 on the outside. The main upright trailing edge 25 and the cylindrical surface of the hub 1 are on the same curved surface and are parallel to the meridian flow surface. The angle α1 between the main straight leading edge 21 and the horizontal line of the meridian flow surface is 81.56 degrees. The splitter blade 3 also includes a secondary straight leading edge 31, a small curved wing 32, a secondary arc guide wing 33, a secondary side wing 34 and a secondary upright trailing edge 35. The splitter blade 3 is used to enhance the workability of the impeller, and together with the main blade 2, pressurizes the incoming gas and makes the pressurized gas evenly distributed on the circumference of the arc-shaped transition section 11 of the hub 1 for discharge; the secondary straight leading edge 31 is arranged at the upper end of the small curved wing 32, and the small curved wing 2 is smoothly transitionally connected with the secondary side wing 34 through the secondary arc guide wing 33, and the secondary upright trailing edge 35 is arranged at the lower end of the secondary side wing 34. The angle α2 between the secondary straight leading edge 31 and the horizontal line of the meridian flow surface is 74.67 degrees. The blade leading edge line attack angle β1 of the main straight leading edge 21 of the main blade 2 and the secondary straight leading edge 31 of the splitter blade 3 are both 0 degrees, so that the main blade 2 and the splitter blade 3 can evenly transition and connect the supercharging process well, ensuring that the airflow can smoothly transition for supercharging operation.

[0024] The main arc lead wing 23, the main side wing 24 and the main upright trailing edge 25 of the main blade 2 can be connected to the shape of the secondary arc lead wing 33, the secondary side wing 34 and the secondary upright trailing edge 35 of the splitter blade 3, and the main upright trailing edge 25 and the secondary upright trailing edge 35 can be arranged parallel to the meridian flow surface. The main side wing 24 and the main upright trailing edge 25 are the same in shape as the secondary side wing 34 and the secondary upright trailing edge 35, and the back bending angle β2 formed by each is 58 degrees.

[0025] As an example, Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, the starting point of the secondary straight leading edge 31 of the splitter blade 3 is located behind the starting point of the main straight leading edge 21 of the main blade 2 and at about 12% of the length of the main blade 2 along the meridian flow surface, that is, the length of the splitter blade 3 is about 88% of the length of the main blade 2. In practical applications, the length of the splitter blade 3 can be in the range of 86% to 90% of the length of the main blade 2. The number of main blades 2 and splitter blades 3 is 13 and they are evenly distributed on the arc-shaped transition section at intervals. The thickness of the main straight leading edge 21 and the secondary straight leading edge 31 are both about 0.6 mm and have an arc-shaped transition. The thickness of the main vertical trailing edge 25 and the secondary vertical trailing edge 35 is about 6 mm, and the blade root fillet 4 is a fillet of R5.

[0026] The present invention adopts a double-sided dynamic balancing experiment, and an additional counterweight screw is placed in the counterweight hole at the front end of the hub 1 to balance the front end imbalance. The dynamic balancing de-weighting belt 6 on the back of the hub 1 removes material by cutting or other methods to eliminate the imbalance, thereby ensuring that the impeller can rotate stably at high speed. At the same time, the main blades 2 and the diverter blades 3 are alternately and evenly distributed on the arc-shaped hub 1, and the structural strength is high, which ensures the extremely high structural strength of the impeller; moreover, the main blades 2 and the diverter blades 3 can pressurize the incoming gas in turn, and the total gas pressure efficiency is high, achieving a maximum rotor efficiency of more than 95% and a compression ratio of more than 2.7, and the uniformity of the airflow pressurization is good, so that the impeller rotates with high roundness accuracy under ultra-high speed rotation, the vibration of the impeller is reduced, the centering ability of the impeller is enhanced, the noise is reduced, and the durability is enhanced, thereby ensuring a relatively long and stable service life. The impeller of the present invention is at the top level worldwide.

[0027] The impeller rotor efficiency is higher than 95% (verified by experiments), and the rotor pressure ratio is higher than 2.7 (verified by experiments).

[0028] When installing the impeller, the smaller diameter end of the impeller belongs to the air inlet side of the compressor, and the larger diameter end of the impeller belongs to the air outlet side of the compressor. The present invention particularly relates to the impeller inlet hub diameter D11 = 127.86mm, the inlet blade diameter D12 = 263mm, and the maximum diameter of the impeller is D2 = 486mm. The full three-dimensional flow design method is adopted, and the blade profile and surface are numerically optimized to obtain the best aerodynamic shape layout. The surface profile of the blade is fitted by the Bezier curve of the whole cycle, and the smoothness is excellent, achieving a maximum rotor efficiency of more than 95% and a compression ratio of more than 2.7, which is at the top level worldwide.

[0029] In addition, as long as the hub and blades are processed separately and then welded together, their aerodynamic shape should also be within the scope of protection of this claim.

[0030] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0031] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A semi-open centrifugal impeller with splitter blades, characterized in that: Including hub, main blades, splitter blades, blade root fillet, dynamic balancing weight holes and dynamic balancing weight removal belt; The main blades also include a main straight leading edge, a main bent wing, a main arc leading wing, a main side wing and a main upright trailing edge. The main blades are used to increase the inlet flow capacity and the workmanship of the impeller. The splitter blades also include a secondary straight leading edge, a small curved wing, a secondary arc leading wing, a secondary side wing and a secondary upright straight trailing edge. The splitter blades are used to enhance the workability of the impeller; The hub is convex, and a concave arc-shaped transition section is provided on the hub. The main blades and splitter blades are evenly distributed on the arc-shaped transition section and are reinforced and connected to the hub through the blade root fillet. The rear end face of the hub is arc-shaped, and the dynamic balance counterweight hole and the dynamic balance deweighting belt are respectively arranged on the upper and lower end faces of the hub to enhance the structural strength. The angle α1 between the main straight leading edge and the horizontal line of the meridian flow surface is 81.56 degrees, and the angle α2 between the secondary straight leading edge and the horizontal line of the meridian flow surface is 74.67 degrees. The main straight leading edge of the main blade and the secondary straight leading edge of the splitter blade are The blade leading edge line attack angle β1 is 0 degrees, the starting point of the secondary straight leading edge of the splitter blade is located behind the starting point of the main straight leading edge of the main blade and at 12% of the length of the main blade along the meridian flow surface, that is, the length of the splitter blade is 88% of the length of the main blade, the number of the main blade and the splitter blade are 13 and are evenly distributed on the arc-shaped transition section at intervals, the thickness of the main straight leading edge and the secondary straight leading edge are both 0.6 mm and have an arc-shaped transition, the thickness of the main vertical straight trailing edge and the secondary vertical straight trailing edge is 6 mm, and the blade root fillet is R5.

2. A semi-open centrifugal impeller with splitter blades according to claim 1, characterized in that: The main straight leading edge is at the outermost end of the main curved wing and close to the air inlet side of the upper end of the hub. The main curved wing is bent in the opposite direction to the rotation direction of the impeller. The main curved wing is smoothly connected to the main side wing through the main arc guide wing. A main vertical straight trailing edge is arranged on the outside of the main side wing. The main vertical straight trailing edge and the cylindrical surface of the hub are on the same arc surface and are parallel to the meridian flow surface.

3. A semi-open centrifugal impeller with splitter blades according to claim 1, characterized in that: The secondary straight leading edge is arranged at the upper end of the small curved wing, the small curved wing is smoothly transitionally connected with the secondary side wing through the secondary arc guide wing, and a secondary upright straight trailing edge is arranged at the lower end of the secondary side wing.

4. A semi-open centrifugal impeller with splitter blades according to claim 1, characterized in that: The main arc wing, main side wing and main vertical trailing edge are connected to each other and the secondary arc wing, secondary side wing and secondary vertical trailing edge are completely identical in shape. The main vertical trailing edge and the secondary vertical trailing edge are parallel to the meridian flow plane.

5. A semi-open centrifugal impeller with splitter blades according to claim 1, characterized in that: The main wing and the main upright trailing edge have the same shape as the secondary wing and the secondary upright trailing edge, and the rearward bending angle β2 formed by each of them is 58 degrees.

Images