CN112177684B

CN112177684B - Turbine blade trailing edge crack cooling structure adopting sawtooth type partition ribs

Info

Publication number: CN112177684B
Application number: CN202011052625.4A
Authority: CN
Inventors: 孔星傲; 吕东; 王楠; 康浩; 刘英实
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2020-09-29
Filing date: 2020-09-29
Publication date: 2021-08-20
Anticipated expiration: 2040-09-29
Also published as: CN112177684A

Abstract

The invention belongs to the technical field of aircraft engine turbine cooling, and relates to a turbine blade trailing edge slot cooling structure adopting sawtooth type partition ribs. The tail edge exhaust split-joint channel of the invention presents a zigzag wave-shaped structure in the leaf thickness direction, and the split-joint partition ribs have a saw-toothed concave-convex structure in the leaf height direction, thereby prolonging the flow path of cold air in a limited design space. According to the invention, the tail edge exhaust split joint is designed into a wave-shaped structure which oscillates in a reciprocating manner along the leaf thickness direction, and meanwhile, a plurality of saw-tooth type tail edge split joint partition ribs are arranged in the split joint, so that the convection heat exchange area is increased by the zigzag exhaust channel and the concave-convex saw-tooth structure. According to the trailing edge slot cooling structure provided by the invention, the channel is wavy in the blade thickness direction, the wall surface of the partition rib is zigzag, disturbance and oscillation are generated to the flow of cold air, and the boundary layer can be blown off and the thickening of the boundary layer can be inhibited.

Description

Turbine blade trailing edge crack cooling structure adopting sawtooth type partition ribs

Technical Field

The invention belongs to the technical field of aircraft engine turbine cooling, and relates to a turbine blade trailing edge slot cooling structure adopting sawtooth type partition ribs.

Background

For aircraft engines and gas turbines, increasing the pre-turbine gas temperature can greatly increase the efficiency of the device, but the cooling of the turbine blades is caused by the gas ambient temperature being much higher than the current material bearing capacity. At present, the turbine blade is generally designed in a hollow mode, heat is taken away through enhanced convection heat exchange of cooling air in the turbine blade, and an air film is formed when the cooling air is discharged out of the turbine blade to cover and isolate fuel gas for heating, so that the turbine blade cooling device is a main solution for the turbine blade cooling problem.

The trailing edge region of the turbine blade is heated by combustion gases from both the bowl side and the back side of the blade, and is structurally thin and difficult to form a hollow cooling structure, thus being a region of the blade that is difficult to cool and a region where the wall surface is hot and prone to ablation during operation. When designing a cooling structure of the blade tail edge, how to more fully cool the blade tail edge area on the premise of ensuring the sufficient strength of the blade and not damaging the good aerodynamic performance of the blade is a problem to be solved. The median slit is a cooling structure commonly used for the trailing edge of a turbine blade. The structure is characterized in that a cold air channel is arranged in the middle of the tail edge of the blade, cold air supplied from the internal channel of the blade enters a cleft slit in the tail edge, and forms enhanced convection heat transfer with the wall surface and the rib structure in the channel, and then flows out from an exhaust edge slit-shaped window in the tail edge of the blade. Known split-in-the-tail-edge structures typically include a plurality of parallel, straight, trailing-edge ribs, referred to as split-in-the-tail-edge ribs, disposed in adjacent channels to direct cooling air chordally away from the blade, as shown in FIG. 1.

The structure of the split seam in the tail edge can keep the structural shape of the tail edge of the blade more completely, and meanwhile, the mixing effect of cooling gas on fuel gas is smaller, so that the mixing loss is lower. Along with the gas temperature's before the turbine constantly rising before, the traditional trailing edge median wedge seam structure is difficult to satisfy the cooling demand of turbine blade trailing edge position, needs to design more effectual novel cooling structure in order to reduce the regional temperature level of blade trailing edge.

Disclosure of Invention

Aiming at the defects of the existing cleft seam cooling technology in the tail edge, the invention provides the turbine blade tail edge cleft seam cooling structure adopting the sawtooth type partition ribs, which can prolong the flow path of cold air, increase the convective heat exchange area and improve the convective heat exchange coefficient of the cold air and the wall surface of a channel on the premise of ensuring the strength and the air performance of the tail edge of the blade, thereby strengthening the convective heat exchange effect of the tail edge and effectively reducing the temperature level of the blade.

The technical scheme of the invention is as follows:

a turbine blade tail edge slot cooling structure adopting sawtooth type partition ribs comprises a hollow turbine blade, an inner cavity cold air channel, a tail edge exhaust slot channel and tail edge slot partition ribs, as shown in figure 2 (a);

the hollow turbine blade is internally provided with an inner cavity cold air channel for low-temperature cooling gas to flow inside the blade to cool the blade. The tail edge of the hollow turbine blade is provided with a wave-shaped tail edge exhaust split along the chord direction, a plurality of saw-tooth tail edge split partition ribs are uniformly arranged in the tail edge exhaust split, and the saw-tooth tail edge split partition ribs are arranged side by side to form a discrete tail edge exhaust split channel for cooling air to be exhausted out of the blade. The structure of the tail edge slot partition rib can not only improve the structural strength of the tail edge of the blade, but also increase the internal heat exchange area of the blade, and guide the cooling air in the inner cavity of the blade to ensure that the flowing direction of the cooling air is turned. The tail edge exhaust crack channel is of a wavy structure in the overlooking dimension, the tail edge crack partition ribs are of a saw-toothed concave-convex structure in the main overlooking dimension, and different crack structures are formed according to different amplitudes, periods and axial line gradients and whether oscillation is attenuated or not.

As shown in FIG. 2(b), in the top cross section of the blade profile, the tail edge exhaust cleft channel is in a wave shape with gradually reduced amplitude and width along the chord direction, and the shape of the tail edge exhaust cleft channel can be controlled by the top center line of the cleft. The center line alternately appears peaks and troughs on both sides of the center line along the normal direction of the center line of the blade-shaped tail edge, and the projection length of each peak and each trough on the center line of the blade-shaped tail edge is half-wavelength L of the overlooking center line of the cleft seam_xThe distance from the top point to the central line of the trailing edge of the blade profile is the amplitude A of the central line when the cleft seam overlooks_x. Along the cold air flowing direction, the center line of the cleft seam is overlooked by half wavelength L_xAnd amplitude A_xGradually decreases to form a gradually attenuated wavy curve on the overlooking central line of the cleft seam. Amplitude A near the trailing edge end of the blade_xThe attenuation is 0 and is overlapped with the central line of the trailing edge of the blade profile, so that the exhaust direction of cooling air is the same as the airflow at the outlet of the blade grid, and the influence on the gas flow when cold air is exhausted is reduced. The overlooking width d of the split gap is symmetrically distributed about the overlooking central line of the split gap and is gradually reduced along the flowing direction of the cold air.

Furthermore, according to the difference of chord length of the tail edge area of the blade, 2-8 wave crests and wave troughs of the overlooking central line of the cleft seam in overlooking dimension are designed, and the amplitude A of the cleft seam is_xCan be 0.1-0.3 times of the thickness of the local blade profile, amplitude/half wavelength (A)_x/L_x) Can be 0.2 to 0.4. The overlooking width d of the cleft seam can be 0.3-0.5 times of the thickness of the local blade profile.

As shown in fig. 2(c), in the front view of the blade, a plurality of zigzag-shaped tail edge split slit partition ribs arranged side by side are uniformly arranged in the tail edge, and discrete tail edge exhaust split slit channels are formed between the tail edge and the partition ribs. The structural shape of the tail edge slot partition rib is controlled by a partition rib central line, and the radial height h of the tail edge slot partition rib is uniformly distributed on two sides of the line to form a sawtooth type tail edge slot partition rib structure. As shown in figure 3, the center line of the barrier ribs alternately appears triangular wave crests and waves along the normal direction at two sides of the axis of the barrier ribsThe valley, forming a jagged curve. The axes of the center lines of the partition ribs can be horizontal straight lines, inclined straight lines or arc-shaped curves, and included angles between tangential directions of the cold air inlet end and the cold air outlet end and a horizontal plane are an incident angle A1 and an emergent angle A2 respectively. One period of the center line of the barrier rib consists of a complete wave crest and a complete wave trough, and the projection length of the wave crest and the wave trough on the axial line is half-wavelength L of the center line of the barrier rib_yThe distance from the peak to the axis is the amplitude A of the center line of the partition rib_yThe half-wavelength L of the center line of the partition rib corresponding to each wave crest and each wave trough_yAnd amplitude A_yMay be the same or different. The formed tail edge gap partition rib is of a triangular sawtooth structure on the two side wall surfaces.

Furthermore, the center line of the partition rib can be designed into 4-12 periods under the main view dimension, and the amplitude A of the center line of the partition rib is_yCan be 0.05 to 0.15 times of the radial height h of the slit partition rib and half-wavelength L of the center line of the partition rib_yThe specific design can be carried out according to the chord length of the blade tail edge area and the period number of the center line of the barrier rib, and the amplitude/half wavelength (A)_y/L_y) Can be 0.1-0.3, and the incident angle A1 and the emergent angle A2 can be 0-45 degrees.

As described above, the blade trailing edge cooling structure of the invention enables the trailing edge exhaust slit channel to form a zigzag wave channel structure in the blade thickness direction, and the trailing edge slit partition ribs have a zigzag concave-convex structure in the blade height direction, so that the flow path of cold air is prolonged in a limited design space, the convection heat exchange area is increased, the heat exchange capacity of the cold air and the channel wall surface is enhanced, and a better cooling effect can be obtained on the premise of not increasing the consumption of the cold air.

The invention has the beneficial effects that:

1 extension cold air flow path makes the cold air utilize more fully:

the existing tail edge middle slit structure adopts a linear exhaust slit channel, so that the length of the channel is more limited in the area of the tail edge of the blade with a narrow space, the flow path of cooling air is short, and the cooling air cannot fully exchange heat with the wall surface of the channel. The tail edge exhaust split-joint channel of the invention presents a zigzag wave-shaped structure in the leaf thickness direction, and the split-joint partition ribs have a saw-toothed concave-convex structure in the leaf height direction, thereby prolonging the flow path of cold air in a limited design space. Compared with the existing split seam structure in the tail edge, the split seam structure can prolong the flow path of the cold air by about 18 percent, thereby leading the cold air to be more fully utilized.

2, increasing the convection heat transfer area:

according to the invention, the tail edge exhaust split joint is designed into a wave-shaped structure which oscillates in a reciprocating manner along the leaf thickness direction, and meanwhile, a plurality of sawtooth type tail edge split joint partition ribs are arranged in the split joint, so that the convection heat exchange area is increased by the zigzag exhaust channel and the concave-convex sawtooth structure. Compared with the existing split seam structure in the tail edge, the invention can increase the heat convection area in the split seam channel by about 14 percent, thereby increasing the heat exchange amount and improving the cooling effect under the condition of not changing the cold air consumption.

3, breaking a boundary layer and strengthening the heat exchange effect:

for the traditional trailing edge median slit structure, cooling air is lack of disturbance in a smooth channel, a stable and thick boundary layer can be formed near the wall surface, and heat exchange between the cooling air and the channel wall surface is blocked. For the trailing edge slot cooling structure provided by the invention, the channel is wavy in the blade thickness direction, the wall surface of the partition rib is zigzag, and the channel and the wall surface all generate disturbance and oscillation on the flow of cold air, so that a boundary layer can be blown off and the thickening of the boundary layer can be inhibited. In addition, the cooling gas has certain impact effect on the wall surface of the channel when turning, and the purpose of heat exchange enhancement can be achieved. As shown in FIG. 5, the numerical simulation calculation shows that, compared with the existing cleft structure in the trailing edge, the invention can improve the heat exchange effect of the region by about 15%, thereby more effectively reducing the temperature level of the trailing edge of the blade.

Drawings

FIG. 1(a) is a view showing a structure of a cleft in the trailing edge of a conventional turbine blade.

FIG. 1(b) is a cross-sectional view of a prior art cleft structure C-C in the trailing edge of a turbine blade.

FIG. 1(c) is an enlarged view of a portion of a prior art cleft in the trailing edge of a turbine blade.

FIG. 2(a) is a view showing a structure of a turbine blade trailing edge cleft using zigzag partition ribs.

FIG. 2(b) is a D-D sectional view of a wave-shaped turbine blade trailing edge cleft structure.

FIG. 2(c) is a partial enlarged view of the horizontal straight zigzag rib structure.

FIG. 3 is a schematic view of the center line of zigzag type barrier ribs.

FIG. 4(a) is a partial enlarged view of the inclined straight zigzag rib structure.

FIG. 4(b) is a partial enlarged view of the zigzag rib structure with a circular arc curve.

FIG. 5(a) is a three-dimensional numerical simulation result of the flow of cold gas inside a cleft structure in the trailing edge of a conventional turbine blade.

FIG. 5(b) is a three-dimensional numerical simulation result of the cold air flow inside the turbine blade trailing edge cleft structure using the zigzag partition ribs.

In the figure: 1. a hollow turbine blade; 2. an inner cavity cold air channel; 3. a trailing edge exhaust slit channel; 4. the tail edge splits the seam and separates the rib; 5. exhausting and splitting the tail edge; 6. the cleft seam overlooks the central line; 7. the center line of the blade profile trailing edge; 8. the top view of the central line wave crest of the cleft seam; 9. the cleft seam overlooks the wave trough of the central line; 10. half-wavelength L of overlooking central line of slit_x(ii) a 11. Amplitude A of center line of overlook of split seam_x(ii) a 12. Overlooking the width d of the cleft seam; 13. the radial height h of the split joint partition rib; 14. the center line of the partition rib; 15. the axis of the center line of the partition rib; 16. incident angle a 1; 17. an emergence angle < A2; 18. wave crest of center line of the partition rib; 19. the center line wave trough of the partition ribs; 20. half-wavelength L of center line of partition rib_y(ii) a 21. Amplitude A of center line of partition rib_y(ii) a 22. A cold air passage partition wall.

Detailed Description

In order that the present invention may be more readily and clearly understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings.

Example 1:

please refer to fig. 2. A turbine blade tail edge slot cooling structure adopting sawtooth type partition ribs comprises a hollow turbine blade 1, an inner cavity cold air channel 2, a tail edge exhaust slot channel 3 and a tail edge slot partition rib 4;

the hollow turbine blade 1 is internally provided with an inner cavity cold air channel 2 which is arranged at the tail edge along the chord directionThe wave-shaped tail edge exhaust split seam 5 is internally and uniformly provided with a plurality of sawtooth-type tail edge split seam partition ribs 4 which are arranged side by side to form a discrete tail edge exhaust split seam channel 3. The channel is in the shape of a wave with gradually reduced amplitude and width along the chord direction, and the shape of the channel can be controlled by the top view central line 6 of the cleft seam. Typically, the number of the wave crests and the wave troughs of the central line in the top-down dimension is designed to be 2, and the amplitude A of the wave crests and the wave troughs_x0.3 times the thickness of the local profile, amplitude/half wavelength (A)_x/L_x) Is 0.2. The overlooking width d of the cleft seam is 0.5 times of the thickness of the local blade profile. The structural shape of the tail edge slot partitioning rib 4 is controlled by a partitioning rib central line 14, and the radial height h of the tail edge slot partitioning rib is uniformly distributed on two sides of the line to form a sawtooth type tail edge slot partitioning rib structure. Typically, as shown in fig. 2(c), the rib center line 14 takes a horizontal straight line as an axis in the primary viewing dimension, the angle a1 is equal to the angle a2 is equal to 0 °, 12 periods are total, and the half-wavelength L of the rib center line corresponding to each peak and trough is half-wavelength L_yAnd amplitude A_ySame, amplitude A_yAmplitude/half wavelength (A) of 0.05 times the radial height h of the ribs_y/L_y) Is 0.3.

Example 2:

the hollow turbine blade 1 is internally provided with an inner cavity cold air channel 2, the tail edge is provided with a wave-shaped tail edge exhaust split joint 5 along the chord direction, a plurality of sawtooth-type tail edge split joint partition ribs 4 are uniformly arranged in the tail edge, and the sawtooth-type tail edge split joint partition ribs are arranged side by side to form a discrete tail edge exhaust split joint channel 3. The channel is in the shape of a wave with gradually reduced amplitude and width along the chord direction, and the shape of the channel can be controlled by the top view central line 6 of the cleft seam. Typically, the number of the wave crests and the wave troughs of the central line in the top-view dimension is designed to be 8, and the amplitude A of the wave crests and the wave troughs_x0.1 times the thickness of the local blade profile, amplitude/half wavelength (A)_x/L_x) Is 0.4. The overlooking width d of the cleft seam is 0.3 times of the thickness of the local blade profile. The structural shape of the tail edge slot partition rib 4 is controlled by a partition rib central line 14, and the radial height h of the tail edge slot partition rib is equal on two sides of the line, so that a sawtooth type tail edge slot partition rib structure is formed. Typically byAs shown in fig. 4(a), the rib center line 14 takes one oblique straight line as an axis in the primary view dimension, the angle a1 is equal to the angle a2 is equal to 45 °, 4 periods are total, and the half-wavelength L of the rib center line corresponding to each peak and trough is half-wavelength L_yAnd amplitude A_ySame, amplitude A_yAmplitude/half wavelength (A) of 0.15 times the radial height h of the ribs_y/L_y) Is 0.1.

Example 3:

the hollow turbine blade 1 is internally provided with an inner cavity cold air channel 2, the tail edge is provided with a wave-shaped tail edge exhaust split joint 5 along the chord direction, a plurality of sawtooth-type tail edge split joint partition ribs 4 are uniformly arranged in the tail edge, and the sawtooth-type tail edge split joint partition ribs are arranged side by side to form a discrete tail edge exhaust split joint channel 3. The channel is in the shape of a wave with gradually reduced amplitude and width along the chord direction, and the shape of the channel can be controlled by the top view central line 6 of the cleft seam. Typically, the number of the wave crests and the wave troughs of the central line in the top-down dimension is designed to be 8, and the amplitude A of the wave crests and the wave troughs_x0.1 times the thickness of the local blade profile, amplitude/half wavelength (A)_x/L_x) Is 0.4. The overlooking width d of the cleft seam is 0.5 times of the thickness of the local blade profile. The structural shape of the tail edge slot partitioning rib 4 is controlled by a partitioning rib central line 14, and the radial height h of the tail edge slot partitioning rib is uniformly distributed on two sides of the line to form a sawtooth type tail edge slot partitioning rib structure. Typically, as shown in fig. 4(b), the rib center line 14 takes one circular arc curve as an axis in the primary viewing dimension, the angle a1 is 45 °, the angle a2 is 0 °, and 12 periods in total, and the rib center line half-wavelength L corresponding to each peak and trough is half-wavelength_yAnd amplitude A_ySame, amplitude A_yAmplitude/half wavelength (A) of 0.05 times the radial height h of the ribs_y/L_y) Is 0.3.

Claims

1. A turbine blade tail edge crack cooling structure adopting sawtooth type partition ribs is characterized by comprising a hollow turbine blade (1), an inner cavity cold air channel (2), a tail edge exhaust crack channel (3) and a tail edge crack partition rib (4);

an inner cavity cold air channel (2) is arranged in the hollow turbine blade (1) and used for low-temperature cooling gas to flow in the blade to cool the blade; the tail edge of the hollow turbine blade (1) is provided with a wavy tail edge exhaust cleft joint (5) along the chord direction, a plurality of sawtooth type tail edge cleft joint partition ribs (4) are uniformly arranged in the tail edge exhaust cleft joint (5) and are arranged side by side to form a discrete tail edge exhaust cleft joint channel (3) for cooling air to be discharged out of the blade;

the tail edge exhaust cleft seam (5) is in a wave shape with gradually attenuated amplitude and width along the chord direction, and the shape of the tail edge exhaust cleft seam can be controlled by a overlooking central line (6) of the cleft seam; the top view central line (6) of the cleft seam alternately appears peaks and troughs on both sides along the normal direction of the central line (7) of the blade-shaped tail edge, and the wave form formed by the peaks and the troughs has the half-wavelength L of the top view central line of the cleft seam_x(10) The distance from the vertex to the central line (7) of the trailing edge of the blade profile is the amplitude A of the central line when the cleft seam is overlooked_x(11) (ii) a Along the cold air flowing direction, the center line of the cleft seam is overlooked by half wavelength L_xAnd amplitude A_xGradually decreases to enable the overlooking central line (6) of the cleft seam to form a gradually attenuated wavy curve; amplitude A near the trailing edge end of the blade_xThe attenuation is 0 and is superposed with the central line (7) of the trailing edge of the blade profile; the overlooking width d (12) of the split seam is symmetrically distributed about the overlooking central line (6) of the split seam and is gradually reduced along the flowing direction of the cold air;

a plurality of zigzag tail edge slit partition ribs (4) which are arranged side by side are uniformly arranged in the tail edge, and discrete tail edge exhaust slit channels (3) are formed between the tail edge and the partition ribs; the structural shape of the tail edge split joint partition rib (4) is controlled by a partition rib central line (14), and the radial height h (13) of the split joint partition rib is uniformly distributed on two sides of the line to form a sawtooth type tail edge split joint partition rib structure; triangular wave crests and wave troughs alternately appear on the center line (14) of the partition ribs along the normal direction on two sides of the axis of the partition ribs to form a sawtooth curve; the axial line of the partition rib central line (14) is a horizontal straight line, an inclined straight line or an arc-shaped curve, and the included angles between the tangential directions of the cold air inlet end and the cold air outlet end and the horizontal plane are an incident angle & lt A1 and an emergent angle & lt A2 respectively; one period of the center line (14) of the partition rib is composed of a complete wave crest and a complete wave trough, and the wave form formed by the wave crest and the wave trough has a half-wavelength L of the center line of the partition rib_y(20) From its apex to the axisThe distance of the lines is the amplitude A of the center line of the partition rib_y(21) The half-wavelength L of the center line of the partition rib corresponding to each wave crest and each wave trough_yAnd amplitude A_yThe same or different; the formed tail edge cleft joint partition rib (4) is of a triangular sawtooth structure on the two side wall surfaces.

2. The turbine blade trailing edge cleft cooling structure adopting sawtooth type partition ribs as claimed in claim 1, wherein the number of peaks and troughs of the top view central line (6) of the cleft is designed to be 2-8 in total in the top view dimension, and the amplitude A of the cleft is_xThe thickness of the local blade profile is 0.1-0.3 times, and the amplitude A_xHalf-wavelength L of overlooking center line of split slit_x0.2 to 0.4; the overlooking width d (12) of the cleft seam is 0.3-0.5 times of the thickness of the local leaf profile.

3. The turbine blade trailing edge slot cooling structure adopting sawtooth type partition ribs as claimed in claim 1 or 2, characterized in that, the partition rib center line (14) is designed with 4-12 cycles in the main view dimension, and the amplitude A is_yIs 0.05 to 0.15 times of the radial height h (13) of the slit partition rib and has a half-wave length L of the center line of the partition rib_yThe amplitude A is designed according to the chord length of the tail edge area of the blade and the period number of the center line (14) of the partition rib_yHalf-wavelength L of center line of partition rib_yIs 0.1 to 0.3, and the incident angle A1 and the emergent angle A2 are 0 to 45 degrees.