A high-speed lightweight impeller and rotor

Abstract

The present invention discloses a high-speed lightweight impeller and rotor, belonging to the technical field of impeller machinery. It includes a first split body and a second split body, the first split body includes a first hub, a first wheel disc and a first blade, the second split body includes a second hub, a second wheel disc and a second blade, the first wheel disc and the second wheel disc have a top end face and a bottom end face along the axial direction respectively, the radius of the top end face is smaller than the bottom end face, the top end face of the first wheel disc is consistent with the outer diameter of the bottom end face of the second wheel disc, and the first blade at the top end face of the first wheel disc is correspondingly connected with the second blade at the bottom end face of the second wheel disc. The present invention has the advantages of improving the stress concentration of the impeller, satisfying the rotor dynamics, and realizing its high-speed operation in a high-temperature environment.

Description

Technical Field

[0001] The invention relates to a high-speed lightweight impeller and a rotor, belonging to the technical field of impeller machinery. Background Art

[0002] With the development of modern turbine machinery, the use of air bearings and electromagnetic bearings has made turbine machinery have the prerequisites to reach high speeds, and users have also put forward higher requirements for efficiency. At present, in order to meet user requirements, the pneumatic design has the problems of high speed and large impeller size after processing. Especially in projects of heat recovery and utilization such as turbine power generation, there is also the operating condition of high temperature environment. This leads to the impeller's strength and rotor dynamics cannot meet the requirements under the conditions of high temperature and high speed. In other words, under the premise of achieving high efficiency, the size, speed and temperature of the impeller are difficult to achieve unity, showing a state of one increasing while the other decreasing. Especially under high temperature conditions, the high-temperature alloy material used in the impeller has high density and heavy weight. The large deadweight will cause the stress it is subjected to during rotation to increase, exceeding the allowable stress of the material. To solve this problem, it is necessary to reduce the weight of the impeller to reduce stress concentration, but weight reduction will weaken the structure of the impeller, and the corresponding impeller strength will also be affected. The strength of the impeller, which is already difficult to withstand, is further weakened, and it is difficult to achieve a balance between the size, speed and temperature of the impeller. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a high-speed lightweight impeller and rotor.

[0004] The objective of the present invention is achieved through the following technical scheme: a high-speed lightweight impeller, comprising a first split body and a second split body, the first split body comprising a first hub, a first wheel disc and a first blade, the second split body comprising a second hub, a second wheel disc and a second blade, the first wheel disc and the second wheel disc having a top end face and a bottom end face at two ends along the axial direction respectively, the radius of the top end face is smaller than the bottom end face, the top end face of the first wheel disc is consistent with the outer diameter of the bottom end face of the second wheel disc, the first blade at the top end face of the first wheel disc is correspondingly connected with the second blade at the bottom end face of the second wheel disc.

[0005] Furthermore, the ratio of the length of the first hub along its axial direction to the length of the second hub along its axial direction is 1:1-3.

[0006] Furthermore, the length of the first hub along its axial direction is not less than 5 mm.

[0007] Furthermore, the first wheel disc and the second wheel disc are both provided with weight-reducing grooves, and the weight-reducing grooves provided on the top end surface of the first wheel disc correspond to the weight-reducing grooves provided on the bottom end surface of the second wheel disc.

[0008] Furthermore, a weight-reducing groove is provided on the bottom end surface of the first wheel disc and the top end surface of the second wheel disc, and the center of the weight-reducing groove is biased toward the outer periphery of the first wheel disc or the second wheel disc.

[0009] Furthermore, the side wall of the weight-reducing groove on the first wheel disc is a hyperbolic surface or a semi-ellipsoidal surface.

[0010] Furthermore, the weight-reducing groove on the first wheel disc has an axial thickness of 2 to 10 mm.

[0011] Furthermore, the weight-reducing groove on the bottom end surface of the second wheel disc includes a first side surface facing the second hub and a second side surface facing the second blade, and the angle between the second side surface or the tangent of the second side surface and the bottom end surface of the second wheel disc is not greater than the angle between the bottom contour line of the second blade and the bottom end surface of the second wheel disc.

[0012] Furthermore, the angle between the end surface of the first blade facing the top end surface of the first disk and the tip profile line does not exceed 90°.

[0013] Another object of the present invention is to provide a rotor, comprising a main shaft and the impeller as described above, wherein a nut for fixing the impeller is sleeved on the main shaft.

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

[0015] 1) By dividing the impeller body into a first part and a second part, the overall mass of the impeller is dispersed and reduced. During the rotation of the first part and the second part, they are mainly affected by their own rotating centrifugal force. Under the action of the rotating centrifugal force, tensile stress and bending stress are generated on the cross-section of the first part and the second part, and the two are combined to form the final comprehensive stress. Among them, the bending stress causes the outer ring of the first part and the second part to be tensile and the inner ring to be compressed, resulting in uneven stress on the entire cross-section. The maximum tangential stress is generated at the inner diameter of the first part and the second part, that is, the inner side of the hub. After the impeller body is divided into two parts, the centrifugal force on the first part and the second part is reduced accordingly, thereby reducing the stress on them, thereby greatly improving the stress concentration of the impeller while satisfying the rotor dynamics.

[0016] 2) By reducing the weight of the first and second parts close to the outer circumference of the impeller, the center of gravity of the first and second parts is moved toward the center. In this way, the average diameter is reduced without changing the rotation speed, and the circumferential speed of the first and second parts is reduced. Therefore, the tangential stress they are subjected to is also reduced accordingly, achieving the purpose of reducing stress, which is also beneficial to reducing the influence of weight reduction on the strength of the impeller.

[0017] 3) The impeller is mounted on the main shaft and a nut is provided at the end of the impeller to fix the first and second parts, so that the top surface of the first part is in close contact with the bottom surface of the second part. The impeller is positioned by utilizing the interference fit between the first and second parts relative to the main shaft and the tightening of the end nut, so that the first and second parts rotate synchronously on the main shaft as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural diagram of embodiment 1 of the present invention.

[0019] Figure 2 It is a schematic structural diagram of the first split body of the first embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of the second embodiment of the present invention.

[0021] Figure 4 This is a cross-sectional stress diagram of comparative example 1 of the present invention.

[0022] Figure 5 This is the stress diagram of the bottom end surface of comparative example 1 of the present invention.

[0023] Figure 6 It is a cross-sectional stress diagram of comparative example 2 of the present invention.

[0024] Figure 7 This is the bottom end surface stress diagram of comparative example 2 of the present invention.

[0025] Figure 8 FIG. 4 is a cross-sectional stress diagram of the first split body according to the first embodiment of the present invention.

[0026] Fig. 9 This is a stress diagram of the bottom end surface of the first split body in Example 1 of the present invention.

[0027] Fig.10 FIG. 4 is a cross-sectional stress diagram of the second split body according to the first embodiment of the present invention.

[0028] Fig.11 This is a stress diagram of the bottom end surface of the second split body in Example 1 of the present invention.

[0029] Fig.12 This is a stress diagram of the top surface of the second split body and the second blade according to the first embodiment of the present invention.

[0030] In the figure, 1, first split body; 11, first hub; 12, first wheel disc; 13, first blade; 2, second split body; 21, second hub; 22, second wheel disc; 23, second blade; 3, top end surface; 4, bottom end surface; 5, weight reduction groove; 6, main shaft; 7, nut. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0032] Embodiment 1

[0033] like Figure 1 and Figure 2 As shown, this embodiment provides a technical solution: a high-speed lightweight impeller, including a first split body 1 and a second split body 2, wherein the first split body 1 includes a first hub 11, a first wheel disc 12 and a first blade 13, and the first hub 11, the first wheel disc 12 and the first blade 13 can be integrally formed, and the second split body 2 includes a second hub 21, a second wheel disc 22 and a second blade 23, and the second hub 21, the second wheel disc 22 and the second blade 23 can also be integrally formed. The structures of the first wheel disc 12 and the second wheel disc 22 are truncated cone-like, the first blade 13 and the second blade 23 are respectively arranged on the outer peripheral curved surfaces of the first wheel disc 12 and the second wheel disc 22, the two ends of the first wheel disc 12 and the second wheel disc 22 along the axial direction are respectively the top end face 3 and the bottom end face 4, the radius of the top end face 3 is smaller than the bottom end face 4, that is, the top end face 3 of the first wheel disc 12 and the second wheel disc 22 is the smaller end face, the bottom end face 4 is the larger end face, and the top end face 3 of the first wheel disc 12 is consistent with the outer diameter of the bottom end face 4 of the second wheel disc 22. When in use, the top end face 3 of the first wheel disc 12 is abutted against the bottom end face 4 of the second wheel disc 22, so that the first split body 1 and the second split body 2 are combined to form an impeller structure. At the same time, the first blade 13 at the top end face 3 of the first wheel disc 12 is correspondingly connected with the second blade 23 at the bottom end face 4 of the second wheel disc 22, that is, after the first split body 1 and the second split body 2 are combined, the first blade 13 and the second blade 23 can form a whole.

[0034] like Figure 1 and Figure 2As shown, in order to ensure the strength of the first sub-body 1 and the second sub-body 2 and to disperse the stress on the impeller, the ratio of the length of the first hub 11 along its axial direction to the length of the second hub 21 along its axial direction in this embodiment is 1:2, that is, the thickness ratio of the first sub-body 1 and the second sub-body 2 is 1:2. In other embodiments, the thickness ratio of the first sub-body 1 and the second sub-body 2 can be adjusted according to the situation that the maximum stress on the original impeller exceeds the allowable stress of the material. The length of the first hub 11 along its axial direction is not less than 5mm, that is, the thickness of the first sub-body 1 is greater than or equal to 5mm. On the first sub-body 1, the angle between the end face of the first blade 13 facing the top end face 3 of the first wheel disc 12 and the blade tip profile does not exceed 90°, that is, the angle between the right end face of the first blade 13 and the blade tip profile on the first sub-body 1 is an acute angle. The angle between the right end surface of the first blade 13 and the blade tip line is preferably 90°. If the angle is too large, the first blade 13 will form a cantilever structure, increasing additional torque. If the angle is too small, the second blade 23 will increase the torque.

[0035] like Figure 1 and Figure 2As shown, in order to give full play to the performance of the material, a weight-reducing groove 5 is provided on both the first wheel disc 12 and the second wheel disc 22. The weight-reducing groove 5 is provided on the bottom end surface 4 of the first wheel disc 12 and the top end surface 3 and the bottom end surface 4 of the second wheel disc 22. The weight-reducing groove 5 provided on the top end surface 3 of the first wheel disc 12 corresponds to the weight-reducing groove 5 provided on the bottom end surface 4 of the second wheel disc 22, that is, after the top end surface 3 of the first wheel disc 12 and the bottom end surface 4 of the second wheel disc 22 are tightly connected, the weight-reducing grooves 5 on the two can be spliced ​​to form a larger weight-reducing groove 5. In order to make the weight of the first wheel disc 12 and the second wheel disc 22 theoretically the lightest and form an iso-stress disc, the weight-reducing groove 5 is provided at the outer edge of the wheel disc, that is, the center of the weight-reducing groove 5 is biased toward the outer periphery of the first wheel disc 12 or the second wheel disc 22. The side wall of the weight-reducing groove 5 on the first wheel disc 12 of this embodiment is a semi-ellipsoidal surface. Both the hyperboloid and the ellipsoidal surface can achieve a smooth transition of the wall surface of the weight-reducing groove 5, thereby avoiding stress concentration. One of the major axis endpoints of the ellipsoidal surface of this embodiment is the intersection formed by the blade bottom contour line offset 3 to 5 mm to the inner side of the wheel disc and the end surface of the first wheel disc 12, and the other major axis endpoint is located at the chamfer of the first wheel disc 12, which is the major axis of the ellipse. In order to ensure the strength of the first wheel disc 12, the sum of the minor axes of the weight-reducing ellipse on the top end surface 3 and the bottom end surface 4 of the first wheel disc 12 is 1 / 3 to 1 / 2 of the thickness of the first wheel disc 12, that is, the thickness of the weight-reducing groove 5 on the top end surface 3 and the bottom end surface 4 of the first wheel disc 12 along the axial direction is 2 to 10 mm, so as to take into account both the strength of the wheel disc and the degree of stress concentration. The weight-reducing groove 5 on the bottom end surface 4 of the second wheel disc 22 includes a first side surface facing the second hub 21 and a second side surface facing the second blade 23, that is, the weight-reducing groove 5 on the bottom end surface 4 of the second wheel disc 22 is surrounded by two side surfaces, and the shapes of the two side surfaces are not particularly limited here, as long as the angle between the second side surface or the tangent of the second side surface and the bottom end surface 4 of the second wheel disc 22 is not greater than the angle between the bottom contour line of the second blade 23 and the bottom end surface 4 of the second wheel disc 22, that is, the maximum angle of the second side surface or the tangent of the second side surface is parallel to the second blade 23. When the top end surface 3 of the second wheel disc 22 is cut to reduce weight, the effective clamping area between the top end surface 3 of the second wheel disc 22 and the nut 7 should be retained to ensure its clamping effect on the first wheel disc 12 and the second wheel disc 22.

[0036] Embodiment 2

[0037] This embodiment provides a rotor, such as Figure 3 As shown, it includes a main shaft 6 and an impeller of embodiment 1, and a nut 7 for fixing the impeller is sleeved on the main shaft 6. When installing the rotor, the first split body 1 and the second split body 2 are sleeved on the main shaft 6 in sequence, so that the top end surface 3 of the first split body 1 is abutted against the bottom end surface 4 of the second split body 2, and then the nut 7 is used to tighten and fix the first split body 1 and the second split body 2.

[0038] Comparative Example 1

[0039] The existing integrated solid impeller is used as a comparative example of the impeller structure, which includes an integrated hub, a wheel disc and blades, and the mass of the entire impeller is 5 kg.

[0040] Comparative Example 2

[0041] The integrated solid impeller of comparative example 1 is treated with a large hole in the center to reduce weight, that is, the center of the integrated impeller disc is a hollow structure, and the mass of the entire impeller is reduced to 2.9 kg.

[0042] Taking the turbine end impeller of a certain project as an example, the impellers of Example 1, Comparative Example 1 and Comparative Example 2 were used for simulated operation. The operating conditions of the unit were: 50000 RPM, inlet temperature 800°C, outlet temperature 500°C, and the impeller material was GH4220.

[0043] like Figure 4 and Figure 5 As shown, under this speed condition, the rotor dynamics of Comparative Example 1 cannot meet the requirements, and its third-order critical speed is more than 40,000. The critical speed is the speed near which the rotor will vibrate strongly. When the rotor rotates at this speed, it will cause strong vibration of the system. Therefore, under the operating conditions of this unit, the impeller of Comparative Example 1 is prone to vibrate near the critical speed and damage the system.

[0044] like Figure 6 and Figure 7 As shown, under this speed condition, the maximum stress on the impeller of comparative example 2 is 1638 MPa, but the impeller that has undergone large-hole weight reduction treatment is insufficient in structural strength, and this stress greatly exceeds the allowable stress of the material.

[0045] Under this speed condition, the stress on the impeller of the first embodiment is greatly improved. Figure 8 and Fig. 9 As shown in Figure 2, the maximum stress on the first sub-body is only 749.88 MPa. Fig.10 , Fig.11 and Fig.12 As shown, the maximum stress on the second split is only 613.26 Mpa, which solves the problem of weight reduction and stress concentration that are difficult to solve at the same time.

[0046] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A high-speed lightweight impeller, characterized in that: The invention comprises a first body (1) and a second body (2), wherein the first body (1) comprises a first hub (11), a first wheel disc (12) and a first blade (13), and the second body (2) comprises a second hub (21), a second wheel disc (22) and a second blade (23), wherein the first wheel disc (12) and the second wheel disc (22) have a top end surface (3) and a bottom end surface (4) at two ends along the axial direction, respectively, wherein the radius of the top end surface (3) is smaller than the radius of the bottom end surface (4), the top end surface (3) of the first wheel disc (12) and the bottom end surface (4) of the second wheel disc (22) have the same outer diameter, and the first blade (13) at the top end surface (3) of the first wheel disc (12) and the second blade (23) at the bottom end surface (4) of the second wheel disc (22) are correspondingly connected; The first wheel disc (12) and the second wheel disc (22) are both provided with a weight-reducing groove (5), the weight-reducing groove (5) provided on the top end surface (3) of the first wheel disc (12) and the weight-reducing groove (5) provided on the bottom end surface (4) of the second wheel disc (22) correspond in position, and after the top end surface of the first wheel disc and the bottom end surface of the second wheel disc are tightly connected, the weight-reducing grooves on the two can be spliced ​​to form a larger weight-reducing groove; A weight-reducing groove (5) is provided on the bottom end surface (4) of the first wheel disc (12) and the top end surface (3) of the second wheel disc (22). The center of the weight-reducing groove (5) is biased toward the outer periphery of the first wheel disc (12) or the second wheel disc (22). By reducing weight on the first sub-body (1) and the second sub-body (2) in a direction close to the outer periphery of the wheel disc, the center of gravity of the first sub-body (1) and the second sub-body (2) is moved toward the center thereof.

2. A high-speed lightweight impeller according to claim 1, characterized in that: The ratio of the length of the first hub (11) along its axial direction to the length of the second hub (21) along its axial direction is 1:1-3.

3. A high-speed lightweight impeller according to claim 1, characterized in that: The length of the first hub (11) along its axial direction is not less than 5 mm.

4. A high-speed lightweight impeller according to claim 1, characterized in that: The side wall of the weight-reducing groove (5) on the first wheel disc (12) is a hyperbolic surface or a semi-ellipsoidal surface.

5. A high-speed lightweight impeller according to claim 4, characterized in that: The weight-reducing groove (5) on the first wheel disc (12) has an axial thickness of 2 to 10 mm.

6. A high-speed lightweight impeller according to claim 1, characterized in that: The weight-reducing groove (5) on the bottom end surface (4) of the second wheel disc (22) comprises a first side surface facing the second hub (21) and a second side surface facing the second blade (23), and the angle between the second side surface or the tangent line of the second side surface and the bottom end surface (4) of the second wheel disc (22) is not greater than the angle between the bottom contour line of the second blade (23) and the bottom end surface (4) of the second wheel disc (22).

7. A high-speed lightweight impeller according to claim 1, characterized in that: The angle between the end surface of the first blade (13) facing the top end surface (3) of the first wheel disc (12) and the blade tip profile line does not exceed 90°.

8. A rotor, characterized in that: It comprises a main shaft (6) and an impeller according to any one of claims 1 to 7, wherein a nut (7) for fixing the impeller is sleeved on the main shaft (6).

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