CN115126549A

CN115126549A - Blade root of turbine blade and turbine blade

Info

Publication number: CN115126549A
Application number: CN202111056122.9A
Authority: CN
Inventors: 李振亚; 赵峰; 朱幼君; 范雪飞; 边文杰; 王宇轩
Original assignee: Shanghai Power Equipment Research Institute Co Ltd
Current assignee: Shanghai Power Equipment Research Institute Co Ltd
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2022-09-30

Abstract

The invention belongs to the technical field of turbine rotating machinery, and discloses a blade root of a turbine blade and the turbine blade. The blade root includes root upper portion, neck and the root lower part that connects gradually in proper order, and root upper portion is used for being connected with the blade body of turbine blade, and the one end and the root lower part of neck are the connection of falling T style of calligraphy, and the other end is connected with root upper portion, and root upper portion is equipped with first heavy groove that subtracts, and the neck is equipped with the second and subtracts heavy groove, adopts fillet transition formation rim loading face between the side of root lower part top surface and neck. The first weight-reducing grooves and the second weight-reducing grooves are formed in the upper portion of the root and the neck portion, so that the weight of the blade root is reduced, and the blade root is light; the top surface of the lower part of the root and the side surface of the neck are connected to form a wheel rim bearing surface through fillet transition, so that the line type of the blade root is optimized, the stress concentration at the wheel groove of the blade root is not easy to generate, and the risk of blade root fracture is effectively reduced.

Description

Blade root of turbine blade and turbine blade

Technical Field

The invention relates to the technical field of turbine rotating machinery, in particular to a blade root of a turbine blade and the turbine blade.

Background

In the research and development of critical equipment of a supercritical carbon dioxide system power generation cycle, the structural design of a turbine machine is a key point of attention of scientific researchers. Turbine blades are key components of supercritical carbon dioxide turbomachinery to direct fluid flow in a direction and to propel a rotor to rotate. The blades attached to the casing are stationary blades or guide blades, and the blades attached to the rotor are moving blades. In a turbomachine running at a high speed, any blade breakage may cause vibration and even equipment damage, and therefore, the structural design and vibration strength of the blade are critical to the safety and reliability of the turbine unit, and the turbine blade has higher requirements in terms of manufacturing processes and the like than a conventional turbine blade.

A blade is generally composed of three parts, a blade body, a blade root and a blade tip. The blade bodies are working parts of the blades, an airflow channel is formed between the adjacent blade bodies, and steam converts kinetic energy into mechanical energy when flowing through the airflow channel; the blades are fixedly connected to the impeller or the rotary drum through blade roots; the tip refers to the tip of the blade, and the short blade and the middle and long blades are usually connected together at the tip by a shroud to form a blade group. At present, the blade root with a simple structure is often adopted on the rotor, and the structure is shown in figure 1. As the turbomachinery is in a high-temperature and high-pressure working environment and has the characteristics of high rotating speed and frequent starting, the blade root is influenced by centrifugal force, exciting force and a temperature field in the running process, great stress concentration is easily generated at the joint of the lower part 1 of the blade root and the neck part 2, and accidents such as blade fracture and the like can be caused if the maximum stress value at the joint is not reduced.

In the prior art, the blade root has a single structure and large weight, the wheel groove of the blade root is easy to generate large stress, and the quality of the blade has large influence on the stress at the blade root under high rotating speed. Therefore, a blade root with light weight and less stress concentration is needed to solve the above problems.

Disclosure of Invention

It is an object of the present invention to provide a turbine blade root having a reduced weight and a reduced tendency to stress concentrations at the wheel groove.

In order to achieve the purpose, the invention adopts the following technical scheme:

a blade root of a turbine blade, comprising: the upper part of the root, the neck and the lower part of the root are connected in sequence; the upper part of the root part is used for being connected with a blade body of the turbine blade, one end of the neck part is connected with the lower part of the root part in an inverted T shape, and the other end of the neck part is connected with the upper part of the root part; the upper part of the root part is provided with a first weight-reducing groove; the top surface of the lower part of the root part and the side surface of the neck part form a wheel rim bearing surface by adopting fillet transition.

Optionally, the neck is provided with a second lightening slot.

Optionally, the wheel rim bearing surface is formed by sequentially connecting a plurality of arc surfaces with different radii.

Optionally, the upper part of the root is connected with the neck in a T shape, and the opening direction of the first weight-reducing groove is arranged towards the lower part of the root.

Optionally, the first lightening slot has a polygonal or arc-shaped cross-sectional profile in the spanwise direction of the blade.

Optionally, the number of first lightening grooves is two, and the two first lightening grooves are symmetrically arranged about the central axis of the neck.

Optionally, the cross-sectional shape of the second lightening slot in the spanwise direction of the blade is polygonal or elliptical.

Optionally, the top end of the lower part of the root is provided with an upper chamfer.

Optionally, the bottom end of the lower portion of the root is provided with a lower chamfer.

Another object of the present invention is to provide a turbine blade which has good manufacturability, low weight, and relatively low maximum stress, is suitable for most circumferentially mounted turbine blades, and is advantageous for popularization.

a turbine blade comprises a blade body and a blade root of the turbine blade.

Has the advantages that:

the blade root of the turbine blade provided by the invention is provided with the first weight-reducing groove at the upper part of the root, so that the weight of the blade root is reduced, and the light weight of the blade root is realized; the fillet transition is adopted at the connecting surface of the top surface of the lower part of the root and the side surface of the neck to form the wheel rim bearing surface, so that the line type of the blade root is optimized, the stress concentration at the wheel groove of the blade root is not easy to generate, the maximum stress borne by the wheel rim bearing surface is reduced, the fracture risk of the blade root is effectively reduced, the blade root has good manufacturability, and the blade is suitable for most of turbine blades which are circumferentially installed and is favorable for popularization.

Drawings

FIG. 1 is a schematic view of a prior art blade root;

fig. 2 is a schematic view of a blade root according to the present invention.

In the figure:

100. the upper part of the root; 101. a first weight-reducing slot; 200. a neck portion; 201. a second weight-reducing slot; 300. the lower part of the root; 301. a rim bearing surface; 302. chamfering; 303. and (6) chamfering the lower part.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the description of the present invention, unless otherwise explicitly specified or limited, the terms "connected," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integral to one another; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meanings of the above terms in the present invention can be understood in a specific case to those of ordinary skill in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature "on," "above" and "over" the second feature may include the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "right", etc. are used in an orientation or positional relationship based on that shown in the drawings only for convenience of description and simplicity of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

The turbine refers to a power fluid machine having fluid blades, such as a steam turbine, an expander, a turbine, and a compressor. The working principle of the turbine is that a rotor provided with blades rotates at a high speed, and when fluid (gas or liquid) flows through a channel between the blades, the blades and the fluid generate interaction force, so that energy conversion is realized. The structural design of turbine blades as components for directing the flow of a fluid in a turbine is of great importance. The main body of the turbine blade is a blade body, the size of the blade body is related to the flow capacity of fluid, the blade tops are connected through a shroud to form a blade group, and the blades are connected to an impeller or a rotary drum through blade roots. The turbine has the characteristics of high temperature, high pressure, high rotating speed and frequent starting, and if the moving blades arranged on the rotor break off in the high-speed running process of the turbine, equipment vibration is caused, and the equipment is easily damaged. Therefore, the structural design of the blade is not only related to the working efficiency of the unit, but also is important for the safety and reliability of the equipment.

The rotor in the prior art usually adopts a blade root with a single structure, the weight is large, and the stress at the wheel groove of the blade root is concentrated, so that the quality of the blade rotating at a high speed has large influence on the stress at the blade root, and the blade is easy to break at the blade root to influence the normal operation of equipment. The blade root provided by the invention can effectively solve the problems.

The blade root of a turbine blade according to the present invention, as shown in fig. 2, includes an upper root portion 100, a neck portion 200, and a lower root portion 300 connected in sequence. The root upper portion 100 is used for being connected with a blade body of a turbine blade, one end of the neck portion 200 is connected with the root lower portion 300 in an inverted T shape, the other end of the neck portion is connected with the root upper portion 100, a first weight reduction groove 101 is formed in the root upper portion 100, and a bearing surface of a wheel rim is formed by fillet transition between the top surface of the root lower portion 300 and the side surface of the neck portion 200.

According to the blade root, the first weight-reducing grooves 101 are formed in the upper portion 100 of the root, so that the weight of the blade root is reduced, and the light weight of the blade root is realized. The connecting surface between the top surface of the lower part 300 of the root and the side surface of the neck part 200 is in fillet transition to form the wheel rim bearing surface 301, so that the line type of the blade root is optimized, the stress concentration at the wheel groove of the blade root is not easy to generate, the maximum stress borne by the wheel rim bearing surface 301 is reduced, the risk of blade root fracture is effectively reduced, the manufacturability is good, the method is suitable for most of circumferentially installed turbine blades, and the popularization is facilitated.

Referring to fig. 2, the blade root has an i-shaped left-right symmetrical structure, the upper end is a horizontally disposed upper root portion 100, the lower end is a horizontally disposed lower root portion 300, the upper root portion 100 and the lower root portion 300 are parallel to each other, and the upper root portion 100 and the lower root portion 300 are connected by a vertically disposed neck portion 200. The root upper portion 100 and the neck portion 200 are connected in a T-shape, the root upper portion 100 is provided with a first weight-reducing groove 101, and compared with the blade root in the prior art, the blade root in the embodiment is widened on the root upper portion 100, and the shape is changed from a high-narrow type to a thick type. The opening direction of the first lightening groove 101 in the figure is arranged towards the lower part 300 of the root, the cross section along the span direction of the blade is in an inverted U shape, and the vertex adopts fillet transition, so that the fillet transition can effectively reduce stress concentration and prevent cracks from occurring at the vertex due to overlarge stress. In other embodiments, the cross-sectional shape of the first lightening groove 101 along the spanwise direction of the blade may be an arc, a polygon or other shapes, and the cross-sectional area is set according to the strength requirement of the blade root. The first lightening grooves 101 may be square, circular or other through holes formed in the root upper portion 100, and the number of the through holes is set according to the requirement of lightening. It should be noted that the "weight reduction groove" is merely a name given to the component for convenience of description, and is not a limitation on the shape or configuration thereof. Further, the number of the first lightening grooves 101 is a double number, and the first lightening grooves are arranged in an array manner about the central axis of the neck portion 200 to ensure the structural stability. In this embodiment, the number of the first weight-reducing grooves 101 is two, and the two first weight-reducing grooves 101 are arranged in an opposite array with respect to the central axis of the neck portion 200.

The first lightening grooves 101 are formed at the bottom surface of the root upper portion 100 with a downwardly opening groove having one side surface of a concave surface downwardly connected to the side surface of the neck portion 200. In this embodiment, the blade roots with different line types are repeatedly calculated and optimized by considering the strength and weight of the member, and finally it is determined that the connecting portion between the side surface of the concave surface of the first lightening groove 101 and the side surface of the neck portion 200 adopts the arc surface recessed toward the symmetrical plane of the neck portion 200, and then the transition is continued toward the lower portion 300 of the root portion, so as to reduce the weight of the blade root to the maximum extent under the condition that the blade root has sufficient strength. The fillet transition is adopted between the top surface of the root lower part 300 and the side surface of the neck part 200 to form the rim bearing surface 301, and the fillet with larger radius is adopted as far as possible under the condition that the blade root and the rim have certain effective contact area, so that the maximum stress borne by the rim bearing surface 301 can be better reduced. Further, the rim bearing surface 301 may be formed by sequentially connecting a plurality of arc surfaces having different radii, and has a better stress reduction effect compared to a fillet having a single radian. From the view of the spanwise cross section of the blade, the envelope curves of the concave surface formed by the first lightening groove 101, the side surface of the neck portion 200 and the top surface of the root lower portion 300 form a continuous arc line, and the manufacturability is good.

Optionally, the neck 200 is provided with a second lightening slot 201, and the second lightening slot 201 shown in fig. 2 is a rectangular through hole opened in the middle of the neck 200 and symmetrically arranged about the central axis of the neck 200. In other embodiments, the second weight-reducing grooves 201 may be grooves formed on one side of the neck portion 200, or grooves formed on both front and back sides of the neck portion 200, or may be through holes, and the shape thereof may be oval, polygonal, or other shapes, and the number and size thereof are not limited herein, as long as the purpose of reducing weight is achieved while ensuring strength.

Further, in this embodiment, the top of root lower part 300 is provided with upper chamfer 302, and the bottom of root lower part 300 is provided with down the chamfer, and the angle is 45, and in other embodiments, the fillet processing can be done to the top and the bottom of root lower part 300, or the chamfer of other angles is adopted to the chamfer of other angles to make things convenient for the rim installation, avoid taking place to interfere, guarantee unit safe operation, the multistage transition fillet that the low stress concentrates also can be applied to the chamfer molded lines, and the fillet molded lines carry out the optimization of multiversion iterative computation.

The invention also provides a turbine blade comprising the blade root. The blade adopts the enveloping weight reduction and low stress concentration fillet transition and carries out cover amount adjustment. As shown in Table 1, the weight of the improved blade can be reduced from 0.8kg to 0.7kg compared with the unmodified blade, and the reduced weight accounts for 12.5% of the original weight of the blade; the maximum stress value can be reduced from 1080MPa to 753MPa, the reduced maximum stress value accounts for 30.3 percent of the original blade, and the optimization effect is obvious. The improved blade has good manufacturability, light weight and relatively low maximum stress, is suitable for most of circumferentially installed turbine blades, and is beneficial to popularization.

TABLE 1

	Non-improved blade	Improved blade	Ratio of occupation of
				Weight (D)	0.8kg	0.7kg	12.5％
Maximum stress value	1080MPa	753MPa	30.3％

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Numerous obvious variations, adaptations and substitutions will occur to those skilled in the art without departing from the scope of the invention. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A blade root for a turbine blade, comprising: a root upper part (100), a neck part (200) and a root lower part (300) which are connected in sequence; the root upper part (100) is used for being connected with a blade body of the turbine blade, one end of the neck part (200) is connected with the root lower part (300) in an inverted T shape, and the other end of the neck part is connected with the root upper part (100); a first weight-reducing groove (101) is formed in the upper part (100) of the root; and a fillet transition is adopted between the top surface of the lower part (300) of the root part and the side surface of the neck part (200) to form a wheel rim bearing surface.

2. Blade root of a turbine blade according to claim 1, characterised in that the neck (200) is provided with a second lightening groove (201).

3. A turbine blade root according to claim 2, characterised in that the cross-sectional shape of the second lightening slot (201) in the spanwise direction of the blade is polygonal or elliptical.

4. The turbine blade root of claim 1 wherein said rim bearing surface is formed by a plurality of successive arcuate surfaces of different radii.

5. Blade root of a turbine blade according to claim 1, characterised in that the root upper part (100) is connected to the neck (200) in a T-shape, the opening direction of the first lightening slot (101) being arranged towards the root lower part (300).

6. Blade root of a turbine blade according to claim 5, characterised in that the first lightening slot (101) has a polygonal or curved cross-sectional profile in the spanwise direction of the blade.

7. Blade root of a turbine blade according to claim 1, characterised in that the number of first lightening slots (101) is two, the two first lightening slots (101) being arranged symmetrically with respect to the central axis of the neck (200).

8. Blade root of a turbine blade according to claim 1, characterised in that the top end of the lower root part (300) is provided with an upper chamfer (302).

9. Blade root for a turbine blade according to claim 1, characterised in that the bottom end of the lower root portion (300) is provided with a lower chamfer (303).

10. A turbine blade comprising a blade body and a blade root, characterized in that the blade root is the blade root of a turbine blade according to any one of claims 1-9.