CN106761952B - A kind of cooling duct, cooling duct group and apply its turbo blade - Google Patents

Abstract

A cooling passage, a cooling passage group and a turbine blade using the same, the cooling passage includes at least one level of bifurcation structure, wherein each level of bifurcation structure includes at least one basic bifurcation unit, and the basic bifurcation unit includes a A root main pipe and at least one branch pipe, wherein at least one branch pipe in the i-level branch structure serves as the main pipe in the i+1-level branch structure, where i is a positive integer, and i≥1.

Description

A cooling channel, a cooling channel group and a turbine blade using the same

technical field

The invention relates to the technical field of heat exchange devices, in particular to a cooling passage, a cooling passage group and a turbine blade using the cooling passage, which is especially suitable for cooling the turbine blade of a gas turbine.

Background technique

In order to improve the efficiency of the gas turbine, it is necessary to increase the working temperature and pressure of the combustor, resulting in a high exhaust temperature of the combustor, which makes the cooling structure design of the turbine blades face severe challenges. The commonly used parallel cooling channel design has disadvantages such as low cooling efficiency, uneven cooling, large impact on the mainstream, large impact on structural strength and fatigue life, and easy blockage.

Therefore, it is urgent to design an efficient and durable cooling structure according to the thermal load, aerodynamic load, and strength load characteristics of the turbine blades.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the present invention provides a cooling passage, a cooling passage group and a turbine blade using the same.

One aspect of the present invention provides a cooling channel, including at least one level of bifurcation structure, wherein each level of bifurcation structure includes at least one basic bifurcation unit, and the basic bifurcation unit includes a main pipe and at least one branch pipe , wherein at least one branch pipe in the i-th bifurcation structure serves as the main pipe in the i+1-th bifurcation structure, where i is a positive integer, and i≥1.

Preferably, the cooling channel is an open structure, the main pipe of the first-stage bifurcated structure of the cooling channel includes the inlet of the cooling channel, and the free branch pipe of the at least one-stage bifurcated structure includes the outlet of the cooling channel.

Preferably, the cooling channel has an M-level bifurcation structure, and the basic bifurcation unit includes a main pipe and N branch pipes, wherein each branch pipe in the i-level bifurcation structure serves as the i+1-th bifurcation structure In the supervisor, where M, N, i are all positive integers, and M, N≥1, M-1≥i≥1.

Preferably, the branch pipes of the Mth stage bifurcation structure all include cooling channel outlets, the cooling channels are applied to the turbine blades, and the cooling channel outlets are arranged on the surface of the turbine blades.

Preferably, the outlet of the cooling passage of the branch pipe includes an elbow structure, so that the injection direction of the cooling medium is parallel to the surface of the turbine blade and points to the trailing edge of the turbine blade; and/or the outlet of the cooling passage of the branch pipe includes a multi-hole nozzle.

Preferably, said cooling medium comprises cooling air and/or steam.

Preferably, the inlet of the cooling passage is arranged on the air supply passage of the turbine blade, and the cooling passage is arranged axially and/or circumferentially along the air supply passage.

Preferably, the cooling channel is a closed structure, and also includes at least one level of reverse bifurcation structure, wherein each level of reverse bifurcation structure includes at least one basic reverse bifurcation unit, and the basic reverse bifurcation unit includes a Root main pipe and at least one branch pipe, wherein at least one branch pipe in the jth level reverse bifurcation structure is used as the main pipe in the j+1th level reverse bifurcation structure, where i, j are positive integers, and i, j≥1 , at least one branch pipe in the last-level bifurcation structure communicates with at least one branch pipe in the last-level reverse bifurcation structure.

Preferably, the cooling channel includes: an M-level bifurcation structure, and the basic bifurcation unit includes a main pipe and N branch pipes, wherein each branch pipe in the i-level bifurcation structure serves as the i+1-th bifurcation A supervisor in the structure, wherein M, N, and i are all positive integers, and M, N≥1, M-1≥i≥1; and a P-level inverse bifurcation structure, the basic inverse bifurcation unit includes a supervisor And Q branch pipes, where each branch pipe in the j-th level reverse bifurcation structure is used as the supervisor in the j+1-th level reverse bifurcation structure, where P, Q, j are all positive integers, and P, Q≥1, P-1≥j≥1, wherein, the branch pipes in the M-level bifurcated structure communicate with the branch pipes in the P-level reverse bifurcated structure in one-to-one correspondence, the main pipe in the first-level bifurcated structure includes the inlet of the cooling channel, and the first The main pipes in the stage reverse bifurcated structure include cooling channel outlets.

Preferably, straight pipes are provided between the branch pipes in the Mth-level bifurcation structure and the branch pipes of the P-th-level reverse bifurcation structure.

Another aspect of the present invention provides a set of cooling channels for a turbine blade, including at least one closed cooling channel, and the at least one closed cooling channel is sequentially connected in series from end to end.

Another aspect of the present invention provides a turbine blade, including a cooling channel and/or a cooling channel group.

It can be seen from the above technical solution that a method for designing a turbine blade cooling channel of the present invention has the following beneficial effects:

The bifurcated cooling channel conforms to the heat load distribution characteristics from the surface to the interior of the turbine blade, so the cooling efficiency is high and the temperature distribution is uniform. Moreover, the bifurcated cooling channel can also reduce the damage to the strength of the turbine blade, avoid cracks inside the turbine blade, and It can reduce the occurrence of blockage of the cooling channel by particles and other pollutants, and inhibit the separation of the flow channel on the suction surface;

The outlet of the cooling channel includes an elbow structure, and the injection direction of the cooling medium is parallel to the surface of the blade and points to the trailing edge of the blade. On the one hand, it can increase the coverage area of the air film, and on the other hand, it can suppress the flow channel separation on the suction surface, thereby improving cooling efficiency. and turbine efficiency;

The outlet of the cooling channel is equipped with a porous nozzle to increase the coverage area of the air film.

Description of drawings

Fig. 1 is a schematic structural diagram of a basic bifurcation unit according to an embodiment of the present invention;

Fig. 2 and Fig. 3 are schematic diagrams of the structure of the two-stage bifurcated cooling channel and the three-stage bifurcated cooling channel based on the basic bifurcated unit in Fig. 1, respectively;

Fig. 4 is a schematic structural view of a turbine blade according to an embodiment of the present invention;

5 is a partial schematic diagram of a turbine blade including a cooling channel connected to an air supply channel according to an embodiment of the present invention;

FIG. 6 is a structural schematic diagram of a turbine blade including a plurality of cooling passages connected to an air supply passage according to an embodiment of the present invention;

Figure 7 is a partially enlarged view of Figure 6;

Fig. 8 is a schematic structural diagram of the basic bifurcation unit in the final bifurcation structure of the cooling channel according to another embodiment of the present invention;

Fig. 9 is a schematic structural view of the branch outlet of the basic bifurcation unit in Fig. 8 being arranged on the surface of the turbine blade;

Fig. 10 is a schematic structural view of the basic bifurcation unit in the final bifurcation structure of the cooling channel according to another embodiment of the present invention;

Fig. 11 is a schematic structural diagram of a closed cooling channel according to yet another embodiment of the present invention;

Fig. 12 is a structural schematic diagram of a turbine blade including a closed cooling passage in another embodiment of the present invention;

Fig. 13 is another structural schematic diagram of a closed cooling channel according to another embodiment of the present invention;

Fig. 14 is a schematic structural diagram of a cooling channel group according to a further embodiment of the present invention.

【Symbol Description】

1-turbine blade; 2-blade suction surface; 3-blade leading edge; 4-air supply channel inlet; 5-air supply channel; 6-air supply channel outlet; 7-blade pressure surface; 8-blade trailing edge; 10 - basic branching unit; 11 - main pipe; 12 - branch pipe.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The present invention provides a cooling passage applied to a turbine blade, which includes at least one level of forked structure, wherein each level of forked structure includes at least one basic forked unit, and the basic forked unit includes a main pipe and at least one Root branch pipe, where at least one branch pipe in the i-th bifurcated structure is used as the main pipe in the i+1-th bifurcated structure, where i is a positive integer, and i≥1, the bifurcated cooling channel conforms to the surface of the turbine blade to the inside The characteristics of thermal load distribution, so the cooling efficiency is high and the temperature distribution is uniform.

In one embodiment of the present invention, a cooling channel is provided, which is an open structure and includes a multi-level bifurcation structure, each level of bifurcation includes at least one basic bifurcation unit 10, and Figure 1 is a schematic structural diagram of the basic bifurcation unit , as shown in Figure 1, each basic branching unit includes a main pipe 11 and at least one branch pipe 12, the basic branching unit branch pipe 11 is four in Figure 1, wherein the end of the main pipe 11 is the cooling gas inlet, and the branch pipe 12 The end is a cooling gas outlet. Those skilled in the art can understand that the number of branch pipes in the basic branching unit in this implementation is at least one, and is not limited to four. Here, only four are used as an example for illustration.

Figure 2 and Figure 3 are the schematic diagrams of the two-level bifurcated cooling channel and the structural diagram of the three-level bifurcated cooling channel respectively. As shown in Figures 2 and 3, the first-level bifurcation structure has a basic bifurcation unit, and The branch pipes of the basic branch units in the bifurcation structure are used as the main pipes of the basic bifurcation units in the second-level bifurcation structure, and the branch pipes of the basic bifurcation units in the second-level bifurcation structure are all used as Supervisor of the basic forking unit. The cooling channel in Fig. 2 has a two-stage branching structure, each basic branching unit has 4 branch pipes, and the cooling channel has 4 ² =16 cooling gas outlets. Please refer to FIG. 3 , the cooling channel has a three-level branching structure, each basic branching unit has 4 branch pipes, and the cooling channel has 4 ³ =64 cooling gas outlets. It can be seen that, for a cooling channel with an M-level bifurcated structure, each basic bifurcated unit has N branch pipes, then the bifurcated cooling channel has N ^M cooling gas outlets, M≥2, N≥2. Preferably, as the number of stages increases, the length of the pipeline is shortened and the diameter of the pipeline is reduced.

FIG. 4 is a schematic structural diagram of a turbine blade. As shown in FIG. 4 , the turbine blade 1 includes a plurality of air supply passages 5 with different diameters, which are arranged between the leading edge 3 and the trailing edge 8 of each blade. For turbine vanes, the inlet 4 and outlet 6 of the air supply channel are respectively connected to the gas channels on the hub and casing; for the turbine rotor blades, the inlet 4 of the air supply channel is connected to the gas channel on the hub, and the outlet 6 of the air supply channel is closed . Figure 5 is a partial schematic diagram of a turbine blade including a cooling channel, as shown in Figure 5, the bifurcated cooling channel has a cooling gas inlet, the inlet is connected to the air supply channel, and multiple cooling gas outlets of the bifurcated cooling channel are provided On the surface of the turbine blade, such as the surface of the trailing edge 8 of the blade, the surface of the leading edge 3 of the blade, the suction surface 2 of the blade and/or the pressure surface 7 of the blade as shown in FIG. 4 .

According to the theory of heat transfer, when a high-temperature fluid passes through the surface of an object, under the action of heat convection, heat conduction and heat radiation, the temperature of the surface of the object rises most dramatically, and the temperature gradient near the surface of the object changes the most violently, that is to say, the surface of the object The heat load is the highest; the interior of the object is not affected by heat convection, and heat is mainly transferred through heat conduction. As it goes deeper into the interior of the object, the temperature gradient gradually becomes smaller, and the heat load also becomes smaller. Therefore, in order to improve the cooling efficiency, on the one hand, it is necessary to densely arrange cooling holes on the surface of the object; on the other hand, it is necessary to ensure that the temperature of the cooling fluid reaches the surface of the object as low as possible. It can be seen that the cooling channels should be dense near the surface of the object; the deeper the object is, the more sparse the distribution of cooling channels should be.

Compared with the traditional cooling structure, the bifurcated cooling channel in this embodiment conforms to the heat load distribution characteristics from the surface to the inside of the object, so the cooling efficiency is high. Moreover, the bifurcated cooling channel can also reduce the damage to the strength of the object and avoid cracks inside the object; it can also prevent the cooling channel from being blocked by pollutants such as particles.

In this embodiment, the cooling passage can be a straight pipe or a bent pipe, and the cross section of the cooling passage is circular, elliptical, triangular, polygonal, preferably circular.

In this embodiment, the cooling gas may be cooling air and/or steam, or other cooling media may be used instead of the cooling gas, such as cooling liquid, etc., and cooling air is preferably used in this embodiment. In other embodiments, air cooling and steam cooling can be used at the same time, preferably, the air cooling channel is located at the leading edge 3 of the blade, and the steam cooling channel is located at the trailing edge 8 of the blade.

In this embodiment, as shown in Figure 5, only one turbine blade structure with one cooling channel is shown. In other embodiments, multiple cooling channels can be set in the turbine blade, as shown in Figures 6 and 7, A plurality of cooling passages are arranged in an axial array along the air supply passage 5 at the leading edge of the blade, and a plurality of bifurcated cooling passages may also be arranged along the circumference of the air supply passage 5 .

The present invention also provides another embodiment. For the purpose of brief description, any descriptions of technical features in the above-mentioned embodiment that can be used in the same way are incorporated here, and there is no need to repeat the same descriptions.

Fig. 8 is a schematic structural diagram of the basic bifurcation unit in the final bifurcation structure of the cooling passage in another embodiment, and Fig. 9 is a schematic structural diagram of the branch outlet of the basic bifurcation unit in Fig. 8 being arranged on the surface of the turbine blade. In the example, as shown in Figures 8 and 9, an elbow structure is provided at the branch cooling gas outlet of the basic bifurcation unit of the last-level bifurcation structure of the cooling channel. By adjusting the angle and direction of the elbow bending, the cooling The gas is ejected at a certain angle, preferably in a direction parallel to the blade surface and pointing to the trailing edge of the blade, so that on the one hand, the coverage area of the air film can be increased, and on the other hand, the separation of the flow channels on the suction surface can be suppressed, thereby improving the cooling efficiency and the turbine efficiency. It can be seen from Figure 9 that due to the characteristics of the bifurcated structure, the outlets of the cooling channels are distributed in a two-dimensional area rather than on a straight line. At this time, the outlets of the elbow are not on a straight line. The advantage of this is that the gas The membrane covers a larger area and has a better effect of inhibiting channel separation.

The present invention also provides yet another embodiment. In order to achieve the purpose of brief description, any descriptions of technical features in the above embodiments that can be used in the same way are incorporated here, and the same descriptions do not need to be repeated. In this embodiment, a porous nozzle is provided at the branch cooling gas outlet of the basic bifurcated unit of the last stage bifurcated structure of the cooling channel, as shown in Figure 10, which can increase the coverage area of the gas film, and the porous nozzle is not limited to that shown in Figure 10 The given hemispherical shape can also be in other forms.

The present invention also provides yet another embodiment, which provides a cooling passage, which is a closed structure, which, in addition to the multi-level bifurcated structure in the above-mentioned embodiment, also includes a multi-level reverse bifurcated structure, each reverse bifurcated structure includes At least one basic reverse branch unit, the basic reverse branch unit has the same structure as the basic branch unit, the difference is that the end of the main pipe is used as a cooling gas outlet, and the end of the branch pipe is used as a cooling gas inlet. The branch pipe of the first-level reverse bifurcation structure serves as the supervisor of the second-level reverse bifurcation structure, the branch pipe of the second-level reverse bifurcation structure serves as the supervisor of the third-level reverse bifurcation structure, and so on, as shown in Figure 11. The bifurcated cooling channel adopts a multi-level bifurcated structure to form multiple discrete outlets according to the reverse bifurcation law and adopts a multi-level reverse bifurcated structure to converge into one outlet to form a closed cooling structure.

In this implementation, the cooling gas can be air or steam or other liquids, preferably water vapor. Using steam as the cooling medium, due to the effect of latent heat, the cooling effect of steam is better than that of air. Since the physical properties of steam and air are very different, using steam cooling, the steam must be circulated in the pipeline, and the steam cannot be injected to the outside of the blade.

Fig. 12 is a schematic structural diagram of a turbine blade including a cooling passage in another embodiment. As shown in Fig. 12, the inlet and outlet of the steam are located on the hub and casing respectively, forming a closed passage. Due to the accumulation of the boundary layer on the surface of the hub and casing, the fluid velocity in this area is lower than that in the middle of the blade. Therefore, the heat load near the hub and casing and at the root and tip of the blade is low, while the heat load in the middle of the blade is low. The load is high, and the cooling fluid channels in the middle of the cooling channel structure shown in Figure 11 are denser than those at both ends, and the coverage area is larger, which conforms to the characteristics of the heat load distribution of the blade and can obtain better cooling effect.

In this embodiment, the branch pipes of the last-level bifurcation structure and the reverse bifurcation structure branch pipes of the last-level reverse bifurcation structure are not limited to the direct connection as shown in Figure 11, as shown in Figure 13, the last-level bifurcation structure The branch pipes of the reverse bifurcation structure and the reverse bifurcation structure branch pipes of the last stage are connected through straight pipes to enhance the cooling effect in the middle of the blade.

A further embodiment of the present invention provides a cooling channel group. As shown in FIG. 14, the cooling channel group includes at least one closed cooling channel in another embodiment, and the at least one cooling channel is connected in series from the end to the end. The edge heat load is larger than the trailing edge heat load. Preferably, the inlet of the cooling channel group is located near the leading edge of the blade, and the outlet is located near the trailing edge of the blade.

Those skilled in the art can understand that in the above-mentioned bifurcation structure and/or reverse bifurcation structure of each level of the cooling channel, the structure of the basic bifurcation unit of the bifurcation structure of the same level or different levels can be the same or different, that is, the same or different bifurcation structures can be used. Basic reverse branching units with different numbers of branch pipes, and basic reverse branching units of the same level or different levels of reverse branching structures can have the same or different structures, that is, basic reverse branching units with the same or different number of branch pipes can be used.

The present invention also provides a turbine blade, which includes the cooling channel and/or cooling channel group in the above embodiments, and adopts open film cooling and closed steam cooling comprehensively according to the thermal load and aerodynamic load characteristics of the turbine blade.

So far, the present embodiment has been described in detail with reference to the drawings. Based on the above description, those skilled in the art should have a clear understanding of the present invention.

It should be noted that, in the accompanying drawings or in the text of the specification, implementations that are not shown or described are forms known to those of ordinary skill in the art, and are not described in detail. In addition, the above definition of each element is not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily modify or replace them, for example:

(1) The directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only referring to the directions of the drawings, and are not used to limit The protection scope of the present invention;

(2) The above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, technical features in different embodiments can be freely combined to form more embodiments.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. a kind of cooling duct, it is characterised in that：Including at least primary furcation structure, wherein per primary furcation structure include to A few basic bifurcated unit, the basic bifurcated unit, which includes one, to be responsible for and at least a branch pipe, wherein i-stage bifurcated knot An at least branch pipe in structure is as the supervisor in i+1 grade bifurcation structure, and wherein i is positive integer, and i >=1,

The cooling duct is closed type structure, further includes at least level-one against bifurcation structure, wherein per level-one against bifurcation structure in Including at least one basic inverse bifurcated unit, the basic inverse bifurcated unit includes a supervisor and an at least branch pipe, wherein For j-th stage against at least branch pipe in bifurcation structure as the supervisor in+1 grade of inverse bifurcation structure of jth, wherein i, j are positive integer, And i, j >=1, an at least branch pipe in afterbody bifurcation structure and afterbody are against at least branch pipe in bifurcation structure It is connected.

2. cooling duct according to claim 1, it is characterised in that：The cooling duct has M grades of bifurcation structures, described Basic bifurcated unit includes a supervisor and N root branch pipes, and each branch pipe is as i+1 fraction wherein in i-stage bifurcation structure The supervisor in structure is pitched, wherein M, N, i is positive integer, and M, N >=1, M-1 >=i >=1.

3. cooling duct according to claim 1, it is characterised in that：Cooling media includes cooling air and/or steam.

4. cooling duct according to claim 1, it is characterised in that：The entrance of the cooling duct is set to turbo blade Air supply channel on, the cooling duct is axial and/or circumferentially disposed along the air supply channel.

5. cooling duct according to claim 2, it is characterised in that：The cooling duct includes：

P grades of inverse bifurcation structures, the basic inverse bifurcated unit include a supervisor and Q root branch pipes, and wherein j-th stage is against bifurcation structure In each branch pipe as the supervisor in the inverse bifurcation structure of+1 grade of jth, wherein P, Q, j is positive integer, and P, Q >=1, P-1 >=j >=1,

Wherein, the branch pipe in M grades of bifurcation structures is connected to the branch pipe one-to-one correspondence of P grades of inverse bifurcation structures, first order bifurcated Supervisor in structure includes cooling duct entrance, and the first order includes that cooling duct exports against the supervisor in bifurcation structure.

6. cooling duct according to claim 5, which is characterized in that the branch pipe in the M grades of bifurcation structures and P grades Setting straight pipe is connected between the branch pipe of inverse bifurcation structure.

7. a kind of cooling duct group of turbo blade, including at least one cooling duct described in claim 5 or 6, it is described extremely Few cooling duct head and the tail described in claim 5 or 6 are sequentially communicated series connection.

8. a kind of turbo blade, including the cooling described in claim the 1-6 any cooling duct and/or claim 7 Channel group.