Turbine blade inner cavity particle deposition resisting bionic crescent dune structure applied to micro-channel cooling

Abstract

The invention provides a turbine blade inner cavity particle deposition resisting bionic crescent dune structure applied to micro-channel cooling, and belongs to the technical field of turbulent flow structures. The problems that how to design an appropriate turbulent flow structure to enhance heat exchange and how to prevent a large number of particulate matter from being deposited on the structure to affect the flowing heat exchange characteristic of a pipeline are solved. According to the structure, a plurality of bionic sand dune structures are sequentially arranged in a micro pipeline at equal intervals, each bionic sand dune structure is of an axisymmetric meniscus structure, the protruding side of each bionic sand dune structure is the windward side, cooling gas enters the micro pipeline from an inlet, and the cooling gas is separated at the front edge of the bionic sand dune structure when flowing through the bionic sand dune structures; the airflow in the center direction continues to flow towards the leeward side along the surface of the bionic structure, the other airflow flows backwards along the two sides of the windward side of the bionic sand dune structure, and a low-speed backflow area is formed on the rear side of the sand dune structure along with violent flow field disturbance. The arrangement of the structure can increase the fluid disturbance in the pipeline, and has the function of inhibiting deposition.

Description

Technical Field

[0001] The present invention belongs to the technical field of spoiler structures, and in particular relates to a bionic crescent-shaped sand dune structure for resisting particle deposition in the inner cavity of a turbine blade used for micro-channel cooling, and belongs to a spoiler structure used in the micro-channel of an aircraft engine / gas turbine turbine blade. Background Art

[0002] For aircraft engines and gas turbines that are in long-term service in all weather and all areas, impurities such as sand and dust particles, volcanic ash or salt mist aerosols in the environment are mixed in the air and enter the engine through the air inlet, deposit in the cooling channel inside the blade, and gradually form a certain deposition morphology. The deposition of particles will not only affect the aerodynamic efficiency of the turbine blades, but also change their heat transfer performance, and even directly affect the service life of the turbine blades. Therefore, in order to ensure the safe and reliable operation of the turbine blades under high heat load conditions, it is necessary to design a suitable structure to enhance heat exchange, and at the same time, it should be avoided that a large amount of particles are deposited on the structure to affect the pipeline flow and heat transfer characteristics. Summary of the invention

[0003] In view of this, in order to solve the problem of how to design a suitable turbulence structure to enhance heat transfer while avoiding a large amount of particulate matter deposited on the structure to affect the flow and heat transfer characteristics of the pipeline, the present invention proposes a bionic crescent-shaped dune structure for resisting particle deposition in the inner cavity of a turbine blade for micro-channel cooling.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a bionic crescent-shaped dune structure for resisting particle deposition in the inner cavity of a turbine blade for micro-channel cooling, wherein a plurality of bionic dune structures are arranged in an equidistant manner in the micro-channel, wherein the bionic dune structure is an axisymmetric meniscus structure, and its convex side is the windward side, and the cooling gas enters the micro-channel from the inlet, and is separated at the leading edge when flowing through the bionic dune structure, and the airflow in the center direction continues to flow toward the leeward side along the surface of the bionic structure, and the remaining airflow flows backward along both sides of the windward side of the bionic dune structure, and a low-speed recirculation zone will be formed on the rear side of the dune structure, accompanied by severe flow field disturbances.

[0005] Furthermore, it is processed and manufactured through 3D printing.

[0006] Furthermore, starting from the entrance of the micro-channel, the bionic crescent-shaped dune structure is arranged in parallel and equidistantly at intervals of 0.4 mm at the bottom of the micro-channel. The highest point of the bionic crescent-shaped dune structure is h=0.08 mm, the total length L along the air flow direction is 5h, and the width is 6h.

[0007] Furthermore, the projection lengths of the leeward slope and the windward slope of the bionic crescent-shaped sand dune structure on the plane are l1 and l2 respectively, where l1 = 1.5h, l2 = h.

[0008] A microchannel, in which a number of the above-mentioned bionic crescent dune structures are arranged equidistantly and longitudinally in a microtube.

[0009] Furthermore, the microtube is a rectangular tube, the width of the inlet and outlet of the microtube is 1 mm, the height is 0.3 mm, and the equivalent diameter D at the inlet h = 0.46 mm.

[0010] Furthermore, the length of the microtube is 3.6 mm.

[0011] Furthermore, the inlet of the microchannel is dry air, with a temperature of 700 K and a pressure of 2 MPa.

[0012] Furthermore, the surrounding wall surfaces of the microchannel are all non-slip isothermal wall surfaces, and the wall temperature T W = 900 K.

[0013] A turbine blade with a dune structure, including a number of the above-mentioned microchannels.

[0014] Compared with the prior art, the beneficial effects of the bionic crescent dune structure for anti-particle deposition in the inner cavity of a turbine blade applied to microchannel cooling according to the present invention are as follows:

[0015] 1. The present invention provides a bionic crescent dune flow disturbance structure with anti-particle deposition ability. This structure is modeled by referring to the final evolution form of natural dunes. The arrangement of this structure can increase the fluid disturbance in the pipeline, making the air flow velocity in the upper surface area relatively high, forming a strong horizontal shear flow; at the same time, a transverse secondary flow is generated at the front end of the dune structure, causing the particulate matter mixed in the gas to move towards both sides of the pipeline, and it is difficult to adhere and accumulate on the surface and the rear side position of the dune structure, so it has the function of inhibiting deposition.

[0016] 2. In addition, as the air flow rate at the inlet of the pipeline increases, larger particles will obtain higher kinetic energy, and the energy loss caused by collision is less, so they are not easily deposited, enhancing the effect of inhibiting deposition.

[0017] 3. This structure is simple and compact, and can be manufactured by 3D printing, with good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1 is a schematic diagram of the arrangement position of the microchannel of a turbine blade with a bionic crescent dune structure having anti-particle deposition according to the present invention;

[0020] Figure 2 Schematic diagram of the microchannel with a bionic crescent dune structure arranged according to the present invention, and schematic diagram of the bionic crescent dune structure;

[0021] Figure 3 Numerical simulation boundary conditions of the microchannel of the present invention;

[0022] Figure 4 Local deposition rate contour maps of particles with different particle sizes in a smooth channel and a channel with a bionic dune structure arranged obtained by numerical simulation according to the present invention;

[0023] Figure 5 Comparison of overall deposition rate results of particles with different particle sizes in a smooth channel and a channel with a bionic dune structure arranged obtained by numerical simulation according to the present invention;

[0024] Figure 6 Dimensionless velocity contour map and streamline map in the channel with a bionic dune structure arranged obtained by numerical simulation according to the present invention;

[0025] Figure 7 Local deposition rate contour maps of particles with different particle sizes in two channels under different inlet Reynolds numbers obtained by numerical simulation according to the present invention, where (a) is the local deposition rate contour map of 5.0um particle size particles in two channels under different inlet Reynolds numbers, and (b) is the local deposition rate contour map of 15.0um particle size particles in two channels under different inlet Reynolds numbers;

[0026] Figure 8 Comparison of overall deposition rate results of particles with different particle sizes in two channels under different inlet Reynolds numbers obtained by numerical simulation according to the present invention.

[0027] In the figure: 1 - cold air inlet, 2 - first bionic crescent dune structure, 3 - second bionic crescent dune structure, 4 - third bionic crescent dune structure, 5 - fourth bionic crescent dune structure, 6 - cold air outlet, 7 - blade tip, 8 - blade body, 9 - flange. Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0029] See Figure 1-8Description of this embodiment: A biomimetic crescent dune structure for anti-particle deposition in the inner cavity of a turbine blade applied to microchannel cooling can be manufactured by 3D printing. A number of biomimetic dune structures are arranged in parallel at equal intervals in the microchannel. The biomimetic dune structure is a flow disturbance structure in the channel, starting from the inlet, it is arranged at equal intervals of 0.4 mm parallel to the bottom of the rectangular microchannel. A total of four biomimetic dune structures are provided at the bottom of the rectangular channel, and they are symmetrically distributed on the bottom surface of the channel. Its structure is crescent-shaped, with an overall height of h = 0.08 mm, a total length L along the air flow direction of 5h, and a width of 6h. The projected lengths of the leeward slope and the windward slope of the biomimetic crescent dune flow disturbance model on the plane are l1 and l2 respectively, where l1 = 1.5h and l2 = h.

[0030] A microchannel, in which a number of biomimetic dune structures are arranged in parallel at equal intervals. The microchannel described in this embodiment is a rectangular channel. The width of the channel inlet and outlet is 1 mm, and the height is 0.3 mm. The equivalent diameter D h = 0.46 mm. The length of the entire micro-cooling channel is 3.6 mm.

[0031] The inlet of the microchannel is dry air, with a temperature of 700 K and a pressure of 2 MPa.

[0032] The surrounding walls of the microchannel are all non-slip isothermal walls, and the wall temperature T W = 900 K.

[0033] A turbine blade with a dune structure includes a number of the above microchannels.

[0034] The working principle of the biomimetic crescent dune structure for anti-particle deposition in the inner cavity of a turbine blade applied to microchannel cooling is as follows:

[0035] Under the same Reynolds number, the heat transfer performance of the channel increases with a smaller diameter. By arranging numerous tiny cooling channels (in the order of 100 μm to 1 mm) close to the gas side on the inner wall of the turbine blade, on the one hand, the heat transfer coefficient is increased, and on the other hand, the heat transfer surface area is also increased, making the cooling performance of the tiny channels greatly improved, and the blade cooling more uniform, thus significantly improving the thermal stress caused by uneven heat transfer in the large-scale cooling method and enhancing the reliability and service life of the turbine blade.

[0036] Common flow disturbance structures on the internal cooling channels of traditional turbine blades include fin types (straight fins, inclined fins, V-shaped fins, etc.), dimples, etc. Since the size of the microchannels is small, when arranging flow disturbance structures, the effect of suppressing particle deposition in the channels should be considered to prevent a large amount of particles from depositing or even blocking in the microchannels, which would affect the flow and heat transfer characteristics of the pipeline. The crescent dune is a characteristic topographical structure in the desert. When wind-blown sand flows over a sand pile, the wind speed at the top of the sand pile is high and the air pressure is relatively low. On the leeward side, a vortex is formed, which pushes the sand grains in the wind to both sides of the leeward slope of the sand pile. With the accumulation of sand, the entire sand dune finally forms a stable crescent dune structure. Therefore, using the method of bionics and referring to the formation principle of the surface of the crescent dune, the present invention analyzes the influence of arranging the crescent dune structure on the particle deposition characteristics of the microchannels.

[0037] In order to maximize the flow and heat transfer characteristics of the microchannels of the turbine blade while reducing the influence caused by particle deposition, the present invention proposes a bionic crescent dune structure with anti-particle deposition and arranges it in the microchannels of the turbine blade. This structure is designed by referring to the sand dune structure in the desert. According to Figure 6 As can be seen from the velocity flow field shown: when the cooling gas flows through the channel arranged with the bionic sand dune structure, it can effectively increase the contact area between the fluid and it, break the flow and heat transfer boundary layers, and promote the mixing of hot and cold fluids. At the same time, the arrangement of the sand dune structure generates a high-speed area in its top region, where particles are more likely to obtain a higher relative velocity, which helps to suppress particle deposition.

[0038] In this embodiment, the cooling gas enters the microchannel with the bionic structure from the inlet and separates at the front of the bionic sand dune structure when flowing through it: the air flow in the central direction continues to flow along the surface of the bionic structure towards the leeward side and forms an acceleration area at the top of the sand dune structure; the remaining air flow flows towards the rear along both sides of the front of the bionic sand dune structure, and a low-speed recirculation area will be formed at the rear of the sand dune structure, accompanied by intense flow field disturbance. For the particles attached to the wall surface, when they are subjected to a large wall shear force, they will detach from the wall surface and it is difficult to deposit. Since a high-speed area is generated near the windward side and the top region of the bionic sand dune structure, a high wall shear stress area is formed on the surface of the sand dune structure. At the same time, the particles will obtain a higher relative velocity in the flow field, making the particles easily peeled off from the wall surface by the air flow and continue to move forward along the flow direction. From Figure 4 and Figure 5It can be seen that particles with a particle size smaller than 5 μm have better fluidity and are more likely to move with the airflow to the recirculation area on the leeward side of the bionic dune structure. However, due to the lower probability of collision between small-sized particles and the wall, the particles are not easily deposited in this area. On the contrary, particles with a diameter greater than 5 μm have a larger inertia and are difficult to be captured by the vortices in the channel and collide with the wall. In addition, there is a transverse secondary flow in the channel with the bionic structure, which makes the particles move to both sides and accelerate backward. Therefore, the particle deposition rate decreases significantly compared with that in a smooth channel. From Figure 5 It can be seen that when Re = 3000, for particles with particle sizes of 10 μm, 15 μm, and 20 μm, their deposition rates in the channel with the dune structure decrease to 70.2%, 59.9%, and 31.9% of the deposition rate in the smooth channel, respectively.

[0039] In addition, changing the inlet Reynolds number of the gas also has an impact on the particle deposition rate. During the process of the flow field changing from laminar flow to turbulent flow, due to the enhanced turbulent effect in the flow field, the particle deposition rate increases. Figure 6 ,7 shows that in this embodiment, particles with a particle size smaller than 5 μm have a smaller inertia and are more likely to be affected by turbulence, increasing the probability of collision with the wall. Since the collision area in the channel with the dune structure is larger, the deposition rate of this particle size is higher than that in the smooth channel. For particles with a diameter of 15 μm, when the inlet is in the turbulent condition, as the inlet velocity continues to increase, the particles will obtain a larger initial kinetic energy and are still difficult to deposit even after multiple collisions. The particle deposition rates in both channels will decrease, and the inhibitory effect on particle deposition is stronger when the dune structure is arranged.

[0040] The embodiments of the present invention disclosed above are only used to help explain the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well.

Claims

1. A bionic crescent-shaped sand dune structure for preventing particle deposition in the inner cavity of a turbine blade for microchannel cooling, characterized in that: Several bionic dune structures are arranged in parallel at equal distances in the micro-pipeline. The bionic dune structure is an axisymmetric meniscus structure, and its convex side is the windward side. The cooling gas enters the micro-pipeline from the inlet and is separated at the leading edge when flowing through the bionic dune structure. The airflow in the center direction continues to flow toward the leeward side along the surface of the bionic structure, and the remaining airflow flows backward along both sides of the windward side of the bionic dune structure. A low-speed recirculation zone will be formed on the rear side of the dune structure, accompanied by severe flow field disturbances.

2. The bionic crescent-shaped sand dune structure for preventing particle deposition in the inner cavity of a turbine blade for microchannel cooling according to claim 1, characterized in that: It is manufactured through 3D printing.

3. The bionic crescent-shaped sand dune structure for preventing particle deposition in the inner cavity of a turbine blade for microchannel cooling according to claim 1, characterized in that: Starting from the entrance of the micro-channel, the bionic crescent-shaped dune structure is arranged in parallel and equidistantly at an interval of 0.4 mm at the bottom of the micro-channel. The highest point of the bionic crescent-shaped dune structure is h=0.08 mm, the total length L along the air flow direction is 5h, and the width is 6h.

4. The bionic crescent-shaped sand dune structure for preventing particle deposition in the inner cavity of a turbine blade for microchannel cooling according to claim 3 is characterized in that: The projection lengths of the leeward slope and the windward slope of the bionic crescent-shaped dune structure on the plane are l1 and l2 respectively, where l1 = 1.5h and l2 = h.

5. A microchannel, characterized in that: A number of bionic crescent-shaped sand dune structures as described in any one of claims 1 to 6 are arranged in parallel and at equal distances in the micro-pipes.

6. The microchannel according to claim 5, characterized in that: The inlet of the microchannel is dry air with a temperature of 700K and a pressure of 2MPa.

7. The microchannel according to claim 5, characterized in that: The walls of the microchannel are all no-slip isothermal walls, and the wall temperature T W =900K.

8. The microchannel according to claim 1, characterized in that: The micro-channel is a rectangular channel, the width of the micro-channel inlet and outlet is 1 mm, the height is 0.3 mm, and the equivalent diameter D at the inlet is h =0.46mm.

9. The microchannel according to claim 1, characterized in that: The length of the microchannel is 3.6 mm.

10. A turbine blade with a dune structure, characterized in that: The method comprises a plurality of microchannels as claimed in any one of claims 7 to 9.

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