CN117449916A - A cooling channel applied to the mid-chord area of turbine blades - Google Patents

Abstract

The invention discloses a turbine cooling channel with multiple curves. The blade has 6 curved channels in the chord direction, and 5 shorter and 2 longer cooling channels in the radial direction. The cooling gas enters from the lower part of the channel and is discharged from the upper outlet of the blade through multiple turns. Blades with this form of cooling channel can better weaken the impact of the rotating Cochlear force on the heat transfer of the blade when the blade is rotating. At the same time, they no longer rely on flow structures such as ribs to improve local heat transfer intensity and achieve leading edge surface cooling. and the balance of heat transfer intensity on the trailing edge surface. The blades are less difficult to manufacture, have a more even cooling effect and have a longer service life.

Description

A cooling channel applied to the mid-chord area of turbine blades

Technical field

The present invention relates to the field of turbine machinery, and in particular, to a cooling channel applied in the mid-chord region of a turbine blade.

Background technique

Under high-temperature working conditions, blades in turbine machinery are easily affected by thermal stress, which causes thermal fatigue, deformation and other problems of blade materials. In order to reduce the impact of these problems on turbine mechanical performance and life, cooling channels are often used for active blade cooling. However, traditional cooling channels have problems such as uneven flow and poor cooling effect, which seriously affect the working efficiency and reliability of turbine machinery.

When the turbine blade is rotating, due to the effect of the rotating Cochlear force, there is uneven heat transfer between the leading edge surface and the trailing edge surface of the traditional blade cooling channel. It relies too much on the spoiler structure to improve the local heat transfer intensity. At the same time, the flow around The presence of the structure increases the rate of dust accumulation and shortens the service life of the blade cooling channels.

Contents of the invention

The purpose of the present invention is to provide a cooling channel applied in the mid-chord region of turbine blades, aiming to solve the problems existing in traditional channels.

The present invention is implemented by adopting the following technical solutions:

A cooling channel applied to the mid-chord area of turbine blades. The cooling channel is composed of several S-shaped channels with short radial vertical channels. The outlet of the previous S-shaped channel is connected to the inlet of the next S-shaped channel. The inlet of an S-shaped channel is located at the blade root, and the outlet of the last S-shaped channel is located at the blade tip. The cooling gas enters from the inlet of the first S-shaped channel and is discharged from the outlet of the last S-shaped channel.

A further improvement of the present invention is that the cooling channel has two 180° turning channels in each S-shaped channel. The cooling medium quickly turns in the bends, and the heat transfer intensity in the nearby area can be enhanced through impact and swirl cooling.

A further improvement of the present invention is that the cooling channel is evenly arranged with fins in two shorter vertical channel areas, where the shorter vertical channel area refers to accounting for 40% of the blade cooling area.

A further improvement of the present invention is that the ribs extend obliquely or horizontally along the width direction of the turbine blade.

A further improvement of the present invention is that in order to adapt to changes in the turbine structure, the cooling channel can also choose to flow in from the left side, or choose to flow in from the right side, while outflowing from the opposite side.

A further improvement of the present invention is that the number of S-shaped channels in the cooling channel is at least three.

A further improvement of the present invention is that in order to reduce the temperature difference between the inside and outside of the blade and reduce thermal stress, a number of air film holes are arranged in the cooling channel.

A further improvement of the present invention is that the number of air film hole arrangements is related to the temperature of the external mainstream gas.

The present invention has at least the following beneficial technical effects:

The new turbine cooling channel of the present invention is arranged with multiple 180° turns, so that the disturbance of the working fluid flow in the turning area is greater and the heat exchange capacity is extremely strong.

The vertical channel of the new channel of the present invention is relatively short, and the longest section is only 40% of the height of the blade cooling area. Therefore, the channel is relatively less affected by the rotating Coss force, and the heat transfer between the rotating leading edge surface and the trailing edge surface of the channel is More evenly, if the fins need to be arranged, they can be arranged only in the short vertical channel area, reducing the difficulty of blade manufacturing.

To sum up, the new turbine cooling channel of the present invention can improve the cooling effect of turbine blades while ensuring the performance and life of the turbine machinery.

Description of the drawings

Figure 1 is a schematic structural diagram of the turbine cooling channel of the present invention.

Figure 2 is a simplified schematic diagram of the turbine cooling channel of the present invention.

Figure 3 is a diagram of the heat transfer effect of a traditional cooling channel in a rotating state.

Figure 4 is a comparison chart of the heat transfer effect of the new cooling channel in the rotating state.

Detailed ways

Embodiments of the invention are described in detail below, examples of which are illustrated in the accompanying drawings. The implementation of the present invention is not limited to the above description, and can be appropriately adjusted and improved according to specific needs. And the present invention can be used in combination with other known technologies.

As shown in Figure 1, the present invention implements a cooling channel in the turbine mid-chord region with multiple S-shaped channels. The cooling gas flows in from the bottom and passes through six 180° turns. The flow channel also includes two relatively short vertical long channels, and the cooling fluid finally flows out from the exit of Turn 6.

To facilitate analysis and understanding, Figure 2 shows a simplified cooling channel. Compared with the traditional S-shaped cooling channel, the overall flow channel length of the channel has not changed, and the positions of the inlet and outlet are exactly the same, and it does not completely rely on the bypass structure to improve the combined heat exchange effect.

It should be noted that the cross-sectional area of the cooling channel may be different at different locations. Specifically, it may be determined according to the different surface curvatures at the locations of the channels and the different cooling needs of the regions.

Figure 3-4 shows the comparison of heat transfer effects between new channels and traditional cooling channels. It can be seen intuitively that the heat transfer intensity and uniformity of the new blades are far better than those of traditional channels, and there is no need to add any form of additional flow structure.

Optionally, as shown in Figure 2, in order to further enhance the heat exchange effect of channel 1 and long channel 2, you can consider adding flow structures (ribs, ball sockets, ball convexes, etc.) near these two channels. It can be understood that when arranging the spoiler structure, its space size should be smaller than the cross-sectional area size of the cooling channel flow channel to avoid clogging the cooling channel. The specific layout can be selected based on actual cooling needs and on-site process conditions.

Optionally, when the blade radial length is larger, you can choose to add more S-bend areas.

Optionally, in order for the cooling gas to flow into the cooling channel more conveniently, the inlet of the channel can be set on the left and right sides of the whole, and the cooling effect will not change much.

Optionally, the new channel can also be applied to the leading edge area away from the mid-chord area, and an impingement cooling or air film cooling structure for the leading edge can also be provided at the channel.

Optionally, the new channel can also be applied to the trailing edge area away from the mid-chord area, and a spoiler column array or a trailing edge split structure can also be provided at the channel for the trailing edge.

Optionally, when the temperature of the external mainstream gas is high, in order to reduce the temperature difference between the inside and outside of the blade and reduce thermal stress, mid-chord air film cooling holes can also be added to the leading edge surface and the trailing edge surface. The shape of the holes is not limited.

Optionally, the number of air film hole arrangements is related to the external mainstream gas temperature. The number of air film holes arranged in this part is related to the size of the air film holes and the temperature difference between inside and outside. When the temperature difference is relatively large, a larger number of air film hole arrays with larger sizes need to be arranged to ensure that the air film can well cover the blade surface.

Specifically, 1-3 exhaust film holes are evenly arranged on the suction surface of the turbine blade close to the leading edge (i.e., the long channel 2 and the turns 1, 4, and 5 in the picture). The size and form of the air film holes are variable. .

The specific design steps of the present invention are:

(1) Based on the three-dimensional shape data of the blade, determine the location of the new channel, the number of S-bends, and the location of the entrance and exit.

(2) According to the heat load distribution on the blade surface, determine the blade cooling gas flow rate and check the pressure drop of the cooling channel.

(3) According to the heat load of the blade, select the flow structure of the vertical channel.

(4) Select the form and arrangement of additional air film holes based on the temperature difference between inside and outside and the properties of the blade material.

The above contents are only for illustrating the technical ideas of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made based on the technical ideas proposed by the present invention and based on the technical solutions shall fall within the scope of the claims of the present invention. within the scope of protection.

In the present invention, the width between the outer surface of the blade and the channel can be changed according to the strength of the blade material. Specifically, when the blade strength is poor, the channel cross-sectional area can be appropriately reduced.

Claims (8)

1. A cooling channel for a chord zone in a turbine blade, characterized in that the cooling channel consists of a plurality of radially shorter S-shaped channels of vertical channels, the outlet of the former S-shaped channel being connected to the inlet of the next S-shaped channel, the inlet of the first S-shaped channel being located at the blade root, the outlet of the last S-shaped channel being located at the blade tip, cooling gas entering from the inlet of the first S-shaped channel and exiting from the outlet of the last S-shaped channel.

2. A cooling passage for a mid-chord region of a turbine blade according to claim 1, wherein the cooling passage has 2 180 degree turn passages in each S-shaped passage, the cooling medium turns rapidly at the turn, and heat exchange strength in the vicinity can be enhanced by impingement and swirl cooling.

3. A cooling passage for a chord zone in a turbine blade according to claim 1 wherein the cooling passage is evenly arranged with fins in two shorter vertical passage zones, wherein the shorter vertical passage zone is 40% of the blade cooling zone.

4. A cooling channel for a chord zone in a turbine blade according to claim 3, wherein the rib extends obliquely or horizontally in the width direction of the turbine blade.

5. A cooling passage for a mid-chord region of a turbine blade according to claim 1, wherein the cooling passage is further adapted to accommodate changes in turbine configuration by either a left side inflow or a right side inflow while a side outflow.

6. A cooling passage for a chord zone in a turbine blade according to claim 1 wherein the number of S-shaped passages in the cooling passage is at least three.

7. A cooling passage for a mid-chord region of a turbine blade according to claim 1, wherein a plurality of film holes are disposed in the cooling passage for reducing the temperature differential between the inner and outer surfaces of the blade to reduce thermal stresses.

8. A cooling passage for a mid-chord region of a turbine blade according to claim 1 wherein the number of film holes is dependent on the ambient mainstream gas temperature.