Toothed composite structure high-temperature vane cooling device and cooling method thereof

Abstract

The present application belongs to the technical field of aero-engine and gas turbine, and particularly relates to a tooth type composite structure high-temperature blade cooling device and a cooling method thereof. A straight tooth / flat composite structure is prepared on the surface of a high-temperature turbine blade, and the gas mist two-phase outflow channel is in a trapezoidal structure. The straight tooth structure has an accelerating effect on the liquid droplets in the gas mist two-phase flow, and can accelerate the flow of the gas mist two-phase flow in a passive state. When the main stream air and the gas mist two-phase flow are mixed and pass through the surface of the straight tooth structure and cool the surface, the mixed fluid can quickly pass through the surface of the straight tooth, reach the flat high-temperature area and cool the flat high-temperature area, so that the cooling effects of different areas of the high-temperature blade tend to be uniformized.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine and gas turbine technology, and particularly relates to a high-temperature blade cooling device and cooling method with a toothed composite structure. Background Technology

[0002] One of the core components of aero-engines and gas turbines is the turbine blade. Improved turbine performance, such as high thrust-to-weight ratio and high thrust, relies on advanced aerodynamic and thermodynamic design and high thermodynamic cycle parameters. These high thermodynamic cycle parameters place higher demands on the design, material selection, and cooling of turbine blades. Therefore, efficient blade cooling is a crucial prerequisite for ensuring the safe operation of the turbine.

[0003] Current blade cooling primarily utilizes single-phase working fluids (such as air), with limited research on two-phase flow cooling. Among these, gas-mist two-phase flow exhibits superior cooling performance compared to single-phase fluids due to the latent heat of vaporization of droplets. However, as the gas-mist two-phase flow flows and exchanges heat on the high-temperature blade surface, a large amount of droplets vaporizes, leading to a rapid decrease in the cooling effect. Temperature differences at different locations on the high-temperature blade result in significant thermal stress, which is detrimental to the safe operation of the blade. Therefore, improving the cooling efficiency of gas-mist two-phase flow and ensuring uniformity of cooling efficiency on the high-temperature blade surface are urgent scientific challenges that need to be addressed.

[0004] Therefore, it is necessary to develop heat transfer enhancement methods for novel and efficient gas-mist two-phase flow cooling to provide key technical support for the cooling of turbine blades in new aero-engines and gas turbines. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a high-temperature blade cooling device with a toothed composite structure, the technical solution of which is as follows:

[0006] A toothed composite structure high-temperature blade cooling device is characterized in that the surface of the high-temperature blade is set with a toothed structure, while the remaining high-temperature surface is flat; when the gas-mist two-phase fluid mixes with the mainstream air after passing through the outflow channel, it first passes over the toothed surface to cool the high-temperature blade, and then the two-phase fluid enters the flat area to cool the high-temperature blade.

[0007] Preferably, the tooth structure is an isosceles right-angled straight tooth, with the inclined side of the straight tooth facing the direction of the incoming flow of the two-phase mixed fluid of gas and mist.

[0008] Preferably, the straight tooth is located at the outlet of the outflow channel, and the high-temperature surface is located downstream of the straight tooth.

[0009] Preferably, the gas-mist two-phase fluid reaches the surface of the high-temperature blade through the outflow channel, the side of the outflow channel perpendicular to the surface of the high-temperature blade increases at a certain angle, and the outlet of the outflow channel has a trapezoidal structure.

[0010] Preferably, the gas-mist two-phase fluid is formed by mixing mist droplets and air.

[0011] This invention also discloses a method for cooling high-temperature blades with a toothed composite structure, characterized by comprising the following steps:

[0012] Step 1: Fabricate a trapezoidal outflow channel and a straight tooth / planar composite structure for the high-temperature blade;

[0013] Step 2: The gas-mist two-phase fluid reaches the surface of the straight tooth structure through the outflow channel. The gas-mist two-phase flow mixes with the mainstream air. The mixed fluid passes through the straight tooth structure and is cooled.

[0014] Step 3: The mixed fluid reaches the high-temperature area of ​​the plane and is cooled; the trapezoidal outflow channel diffuses the gas-mist two-phase fluid in the contact range of the straight tooth surface, thereby expanding the cooling area; the straight tooth structure has an accelerating effect on the droplets in the gas-mist two-phase flow, accelerating the flow velocity of the gas-mist two-phase flow in a passive state, thereby making the cooling effect of different areas of the high-temperature blade tend to be uniform.

[0015] Beneficial effects:

[0016] This invention creatively proposes a straight tooth / composite structure. Since the cooling capacity decreases as the liquid droplets evaporate in the two-phase flow of gas and mist, a straight tooth structure is set at the outlet of the outflow channel. Driven by the evaporation power and surface energy of the liquid droplets on the surface of the straight tooth structure, the liquid droplets carry air and accelerate to reach the planar structure area for cooling.

[0017] This invention innovatively proposes a straight-tooth / composite structure, which can enhance the uniformity of cooling for high-temperature turbine blades. It is an efficient and safe cooling method that can solve the problem of high-temperature cooling for turbine blades.

[0018] The simple and reliable straight tooth structure of this invention can achieve uniform cooling area on the high-temperature blade wall. At the same time, the trapezoidal channel can expand the coverage area of ​​the gas-mist two-phase flow on the high-temperature blade, increasing the cooling surface area. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a high-temperature blade cooling device with a toothed composite structure according to the present invention.

[0020] Figure 2 This is a front view of a high-temperature blade cooling device with a toothed composite structure according to the present invention.

[0021] Figure 3 This is a straight tooth structure diagram of a high-temperature blade cooling device with a toothed composite structure according to the present invention;

[0022] Figure 4 This is a schematic diagram of the trapezoidal outflow structure of a toothed composite high-temperature blade cooling device according to the present invention;

[0023] Figure 5 This is a schematic diagram showing the cooling efficiency calculation results of Embodiment 1 of the present invention.

[0024] Among them: 1. Main flow channel, 2. Trapezoidal outflow channel, 3. High temperature blade area, 4. Two-phase flow outlet, 31. Straight tooth area, 32. Planar area. Detailed Implementation

[0025] This invention discloses a toothed composite structure high-temperature blade cooling device, characterized in that a toothed structure is formed on part of the high-temperature blade surface, while the remaining high-temperature surfaces are flat. When the gas-mist two-phase fluid mixes with the mainstream air through the outflow channel, it first passes over the toothed surface to cool the high-temperature blade, and then the two-phase fluid enters the flat area to cool the high-temperature blade. The toothed structure is an isosceles right-angled straight tooth, with the inclined side of the straight tooth facing the direction of the gas-mist two-phase fluid flow. The straight tooth is located at the outlet of the outflow channel, and the high-temperature surface is downstream of the straight tooth. The gas-mist two-phase fluid reaches the surface of the high-temperature blade through the outflow channel, and the side of the outflow channel perpendicular to the surface of the high-temperature blade increases at a certain angle, with the outlet of the outflow channel having a trapezoidal structure. The gas-mist two-phase fluid is formed by the mixture of droplets and air.

[0026] This invention also discloses a method for cooling high-temperature blades with a toothed composite structure, characterized by comprising the following steps:

[0027] Step 1: Fabricate a trapezoidal outflow channel and a straight tooth / planar composite structure for the high-temperature blade;

[0028] Step 2: The gas-mist two-phase fluid reaches the surface of the straight tooth structure through the outflow channel. The gas-mist two-phase flow mixes with the mainstream air. The mixed fluid passes through the straight tooth structure and is cooled.

[0029] Step 3: The mixed fluid reaches the high-temperature area of ​​the plane and is cooled; the trapezoidal outflow channel diffuses the gas-mist two-phase fluid in the contact range of the straight tooth surface, thereby expanding the cooling area; the straight tooth structure has an accelerating effect on the droplets in the gas-mist two-phase flow, accelerating the flow velocity of the gas-mist two-phase flow in a passive state, thereby making the cooling effect of different areas of the high-temperature blade tend to be uniform.

[0030] Air enters the high-temperature blade region 3 through the main flow channel 1. The gas-mist two-phase flow reaches the straight tooth structure 31 of the high-temperature blade through the trapezoidal outflow channel 2. The two fluids then mix and pass over the straight tooth structure 31 for cooling. During the gas-mist two-phase flow heating process, driven by the droplet evaporation kinetics and surface energy, the droplets carry air and accelerate to the planar region 32. After being cooled by the gas-liquid two-phase flow, it is discharged from the outlet 4.

[0031] The preparation of straight tooth structure 3 is as follows Figure 3 As shown, the right-angled side is 1mm long, and the hypotenuse faces the direction of the two-phase flow of the aerosol. The outflow channel is as follows. Figure 4 As shown, the outlet of the outflow channel has a trapezoidal structure, with the two sides of the channel perpendicular to the surface of the high-temperature blade increasing at a certain angle, and the two sides parallel to the high-temperature blade having a parallel structure.

[0032] Implementation Column 1

[0033] The cooling efficiency of two structures—flat surface and straight-tooth / flat surface—in a gas-mist two-phase flow was simulated and analyzed. Based on published literature and previous work, the main parameters of the model included: the turbine high-temperature blades were 320mm × 32mm × 80mm; the outflow channel inlet was an 8mm square, the lower side of the outlet was 16mm, and the angle with the blade was 35°; the length of the straight-tooth region along the flow velocity direction was 10mm, and the remaining high-temperature blade region was flat. The simulation used a mainstream air velocity of 10m / s and a temperature of 400K; the temperature of the gas-mist two-phase flow was 300K, the blowing ratio was 1; the droplet diameter was 10μm, and the droplet mass flow rate was 1%.

[0034] The air-to-flow ratio is the ratio of the product of the coolant inlet density and velocity to the product of the mainstream air inlet density and velocity. The expression for the air-to-flow ratio is as follows:

[0035]

[0036] In the formula: ρ c and ρ m These are the density of the coolant and the density of the mainstream air, respectively, in kg / m³. 3 v c and v m These are the coolant velocity and the mainstream inlet air velocity, respectively, in m / s.

[0037] Cooling efficiency is the ratio of the difference between the mainstream temperature and the wall adiabatic temperature to the difference between the mainstream temperature and the coolant temperature, and its expression is:

[0038]

[0039] In the formula: T m Mainstream temperature, K; T c It is the temperature of the cooling jet, K; T w It is the adiabatic temperature of the blade surface after film cooling, in K.

[0040] The average cooling efficiency is the average cooling efficiency of a specific cross-section within the computational domain. The expression is as follows:

[0041]

[0042] In the formula: l is the cross-sectional length, in meters (m).

[0043] Cooling efficiency is calculated using the vertical axis to represent the average cooling efficiency in the vertical direction of the two-phase airflow, and the horizontal axis to represent the distance from the outlet of the two-phase airflow. The graph shows that cooling efficiency continuously decreases in the direction of the two-phase airflow. Taking a blowing ratio M=1 as an example, the cooling efficiency of the flat surface is higher when x is between 0 and 4. When x is greater than 4, the cooling efficiency of the straight-tooth / flat surface is higher than that of the flat surface. Data analysis shows that the average cooling efficiency of the straight-tooth / flat structure is approximately 26.8%, while the average cooling efficiency of the flat surface is approximately 22.9%. Compared to the flat structure, the cooling efficiency of the straight-tooth / flat structure is improved by 17.0%.

[0044] The results from the above case studies demonstrate that, under the same parameter conditions, the straight-tooth structure accelerates droplet movement, reduces droplet evaporation at the inlet, and increases droplet evaporation on the flat surface, leading to increased cooling efficiency in that area. Therefore, the straight-tooth / flat-surface structure can improve the overall cooling efficiency of high-temperature blades and reduce temperature inhomogeneity at different locations on the high-temperature blades, thus contributing to improved overall cooling temperature uniformity.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A high-temperature blade cooling device with a toothed composite structure, characterized in that, The high-temperature blade surface is designed with a toothed structure, while the remaining high-temperature surfaces are flat. When the gas-mist two-phase fluid mixes with the mainstream air through the outflow channel, it first passes over the toothed surface to cool the high-temperature blade. Subsequently, the two-phase fluid enters the flat area to cool the high-temperature blade. The toothed structure is an isosceles right-angled straight tooth, with the inclined side of the straight tooth facing the direction of the gas-mist two-phase fluid flow. The straight tooth is located at the outlet of the outflow channel, and the high-temperature flat surface is downstream of the straight tooth. The gas-mist two-phase fluid reaches the surface of the high-temperature blade through the outflow channel. The side of the outflow channel perpendicular to the surface of the high-temperature blade increases at a certain angle, and the outlet of the outflow channel is a trapezoidal structure. The gas-mist two-phase fluid is a mixture of droplets and air. The right-angled side of the straight tooth structure is 1 mm long, and the inclined side faces the direction of the gas-mist two-phase flow. The outflow channel is a trapezoidal structure, with the two sides perpendicular to the surface of the high-temperature blade increasing at a certain angle, and the two sides parallel to the high-temperature blade being parallel structures.

2. A method for cooling high-temperature blades with a toothed composite structure, the method being based on the device described in claim 1, characterized in that, Step 1: Fabricate a trapezoidal outflow channel and a straight tooth / planar composite structure for the high-temperature blade; Step 2: The gas-mist two-phase fluid reaches the surface of the straight tooth structure through the outflow channel. The gas-mist two-phase flow mixes with the mainstream air. The mixed fluid passes through the straight tooth structure and is cooled. Step 3: The mixed fluid reaches the high-temperature region of the plane and is cooled; The trapezoidal outflow channel diffuses the gas-mist two-phase fluid within the contact area of ​​the straight tooth surface, thereby expanding the cooling zone. The straight tooth structure accelerates the droplets in the gas-mist two-phase flow, increasing the flow velocity of the gas-mist two-phase flow in a passive state, thus achieving a more uniform cooling effect in different areas of the high-temperature blade.

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