Cooling channel of a turbine blade

Abstract

The present invention provides a cooling channel for a turbine blade, wherein a first main straight channel and a second main straight channel are provided in the blade, the first main straight channel and the second main straight channel being connected to an inlet and an outlet, respectively; the first main straight channel and the second main straight channel are parallel to each other and connected to form a U-shaped cooling channel via an arc-shaped pipe; a leading edge cooling branch channel is provided at the connection between the first main straight channel and the arc-shaped pipe; a trailing edge cooling branch channel is provided at the connection between the second main straight channel and the arc-shaped pipe; the leading edge cooling branch channel and the trailing edge cooling branch channel are located in the leading edge tip and trailing edge tip regions of the blade, respectively. The present invention not only ensures the cooling effect at the center of the blade, but also enhances the cooling effect at the leading and trailing edges of the blade, preventing an overheated area at the leading and trailing edges, while reducing the temperature difference on the blade; and at the same time, utilizing a human ear-shaped cooling branch channel improves the backflow phenomenon in the U-shaped cooling channel.

Description

Technical Field

[0001] The invention provides a cooling channel for a turbine blade, belonging to the technical field of turbines. Background Art

[0002] With the development of the aerospace field, the flight speed of aircraft is getting faster and faster, resulting in excessively high working temperature of turbine components. The temperature of the gas before the turbine can reach over 1600K, which has exceeded the limit of the turbine blade material. In order to ensure the safety of the turbine during operation, the turbine blades must be cooled. Aircraft engines usually use lower temperature air for cooling, but for aircraft used in the aerospace field, such as hypersonic aircraft and rockets, the air temperature inside is also very high due to the high flight speed. However, due to weight restrictions, a separate cooling source cannot be carried, so the aircraft's fuel is usually used to cool the various components. At the same time, the increase in fuel temperature is also conducive to the subsequent combustion to release more energy.

[0003] For fuel-cooled turbines, since the fuel is typically high-molecular-weight hydrocarbons like jet fuel, they crack into smaller hydrocarbons when exposed to high temperatures. While this cracking phenomenon facilitates subsequent combustion and energy release, it also causes carbon deposits in the cooling channels, hindering the flow of coolant and compromising cooling effectiveness. Furthermore, the inherent viscosity of the fuel forces the cooling channels within the blades to employ simple structures, significantly different from those in air-cooled turbines.

[0004] Currently, blade cooling technology using U-shaped cooling channels is being widely studied. Under rotating conditions, the turbulence inside the channel is relatively high, which can enhance heat exchange, but it will also cause backflow in the channel, increase flow resistance, and generate flow losses.

[0005] Therefore, how to use a simple cooling channel structure to ensure the cooling effect of the turbine blades while improving the backflow phenomenon caused by the rotating centrifugal effect is the focus of the design. Summary of the Invention

[0006] The present invention aims to provide a cooling channel for turbine blades that expands the cooling range of the blades, ensuring cooling at the blade center while also enhancing cooling at the leading and trailing edges. This prevents overheating at the leading and trailing edges, while minimizing temperature differences across the blades and thus reducing thermal stress. Furthermore, the use of ear-shaped cooling channels improves backflow within the U-shaped cooling channel.

[0007] The technical means adopted by the present invention is to add two human ear-shaped cooling sub-channels to the leading edge and the trailing edge of the U-shaped cooling channel.

[0008] The specific technical solutions are:

[0009] A cooling passage for a turbine blade includes an inlet and an outlet at the bottom of the blade;

[0010] A first main flow straight channel and a second main flow straight channel are provided in the blade, and the first main flow straight channel and the second main flow straight channel are connected to the inlet and the outlet respectively;

[0011] The first main flow straight channel and the second main flow straight channel are parallel to each other and connected to form a U-shaped cooling channel through an arc-shaped pipe;

[0012] A leading edge cooling sub-channel is provided at the connection between the first main flow straight channel and the arc-shaped pipe;

[0013] A trailing edge cooling branch channel is provided at the connection between the second main flow straight channel and the arc-shaped pipe;

[0014] The leading edge cooling sub-channel and the trailing edge cooling sub-channel are respectively located in the leading edge tip and the trailing edge tip area of the blade.

[0015] The leading edge cooling sub-channel and the trailing edge cooling sub-channel are both human ear-shaped cooling sub-channels.

[0016] The distance τ between the top of the U-shaped cooling channel and the blade tip is 2.75 mm, the spacing d between the first and second main flow straight channels is 4.5 mm, the diameter Φ1 of the U-shaped cooling channel is 1.5 mm, the diameter Φ3 of the leading edge cooling channel is 0.5 mm, the inlet structural angle α1 is 45°, the outlet structural angle α2 is 64°, and the angle β2 with the plane of the U-shaped cooling channel is 22°. The diameter Φ2 of the trailing edge cooling channel is 0.8 mm, the inlet structural angle α3 is 35°, the outlet structural angle α4 is 40°, and the angle β1 with the plane of the U-shaped cooling channel is 20°.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0018] 1. The addition of two cooling channels to the leading and trailing edges of the blades expands the cooling area of the blades and enhances the cooling effect of the cooling fuel on the leading and trailing edges near the blade tip.

[0019] 2. Due to the enhanced cooling effect of the leading and trailing edges of the blade, the temperature difference between the periphery of the blade and the center of the blade is reduced, thereby reducing the thermal stress on the blade;

[0020] 3. Since the cooling channel adopts a human ear-shaped structure, it has one-way flow capability and large reverse flow resistance. Adding this structure at the turning point of the U-shaped cooling channel can reduce backflow. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the turbine blade cooling channel of the present invention

[0022] Figure 2 This is a schematic diagram of the dimensions of the turbine blade cooling channel of the present invention;

[0023] Figure 3 This is a schematic diagram of the angle of the cooling channel structure of the present invention;

[0024] Figure 4 Schematic diagram of the angle between the cooling sub-channel and the plane where the U-shaped cooling channel is located. DETAILED DESCRIPTION

[0025] The specific technical solutions of the present invention are described with reference to the embodiments.

[0026] like Figure 1 As shown, a cooling channel of a turbine blade includes an inlet 1 and an outlet 2 at the bottom of the blade 7;

[0027] A first main flow straight channel 3 and a second main flow straight channel 8 are provided in the blade 7, and the first main flow straight channel 3 and the second main flow straight channel 8 are communicated with the inlet 1 and the outlet 2 respectively;

[0028] The first main flow straight channel 3 and the second main flow straight channel 8 are parallel to each other and connected by an arc-shaped pipe 5 to form a U-shaped cooling channel;

[0029] A leading edge cooling branch channel 4 is provided at the connection between the first main flow straight channel 3 and the arc-shaped pipe 5;

[0030] A trailing edge cooling branch channel 6 is provided at the connection between the second main flow straight channel 8 and the arc-shaped pipe 5;

[0031] The leading edge cooling sub-channel 4 and the trailing edge cooling sub-channel 6 are respectively located in the leading edge tip and the trailing edge tip region of the blade 7 .

[0032] The leading edge cooling sub-channel 4 and the trailing edge cooling sub-channel 6 are both human ear-shaped cooling sub-channels.

[0033] The operating principle is as follows: cooling fuel enters the first main flow channel 3 through inlet 1 near the base of the blade 7, exchanges heat with the blade 7, then passes through the arc-shaped conduit 5 and the second main flow channel 8, finally flowing out through outlet 2. At the junction of the first main flow channel 3 and the arc-shaped conduit 5, a portion of the cooling fuel flows into the leading edge cooling branch channel 4, which then merges into the arc-shaped conduit 5. At the junction of the arc-shaped conduit 5 and the second main flow channel 8, a portion of the cooling fuel flows into the trailing edge cooling branch channel 6, cooling the blade's trailing edge, before merging into the second main flow channel 8.

[0034] First, the first main flow straight channel 3 of the turbine blade 7 is connected by an arc-shaped pipe 5, which prevents flow separation and vortex formation caused by curvature discontinuity, thereby reducing flow losses within the U-shaped cooling channel. To prevent the leading and trailing edges of the blades from being undercooled near the blade tip, resulting in overheating, two human ear-shaped cooling sub-channels are introduced from the U-shaped cooling channel: the leading edge cooling sub-channel 4 and the trailing edge cooling sub-channel 6. This allows a portion of the cooling fuel to flow from the U-shaped cooling channel into the cooling sub-channels, cooling the leading and trailing edges near the blade tip through the cooling sub-channels. Simultaneously, due to the high-speed rotation of the blades, the U-shaped cooling channel's turning point is affected by centrifugal force, Coriolis force, buoyancy, and curvature effects during turbine operation, generating complex vortex structures within the channel and causing backflow. Because the human ear-shaped structure is similar to that of a Tesla valve and has unidirectional conduction capabilities, it creates significant resistance to reverse flow. Therefore, adopting a human ear-shaped structure for the cooling sub-channels effectively prevents backflow within the U-shaped cooling channel and reduces flow resistance. In this way, adding a human-ear-shaped cooling sub-channel near the turning point of the U-shaped cooling channel not only cools the leading and trailing edges near the blade tip, but also utilizes the one-way flow capability of a Tesla-like valve to suppress backflow near the turning point. Simultaneously, the cooling sub-channel expands the cooling area of the blade, enhancing the cooling effect around the blade, thereby reducing the temperature difference between the blade perimeter and the center. Because the thermal expansion and contraction of the blade are restricted, the high-temperature area expands and elongates, while the low-temperature area restricts its expansion. This generates compressive stress in the high-temperature area and tensile stress in the low-temperature area, i.e., thermal stress. Assuming the internal temperature difference of an object is T(x, y, z) and the object's thermal expansion coefficient is α, the thermal expansion of the object is α*T. Since thermal stress is positively correlated with expansion, the smaller the temperature difference T, the smaller the thermal stress. This also reduces the thermal stress on the blade.

[0035] Various parameters can be adjusted and selected according to the specific blade shape. The recommended parameter ranges are as follows:

[0036] Table 1 Parameter recommended values

[0037]

[0038]

[0039] Secondly, the present invention can be a combination of some forms mentioned in the technical solution, which can be selected according to the actual situation. For example: if the leading edge cooling effect is good, the leading edge cooling sub-channel can be omitted, and only the arc connection and the trailing edge cooling sub-channel can be selected; if the straight channel produces backflow, a human ear-shaped cooling sub-channel is added to the straight channel.

[0040] As a preferred Figure 2As shown, in this embodiment, the distance τ between the top of the U-shaped cooling channel and the blade tip is 2.75 mm, the distance d between the first main flow straight channel 3 and the second main flow straight channel 8 is 4.5 mm, the diameter Φ1 of the U-shaped cooling channel is 1.5 mm, the diameter Φ3 of the leading edge cooling channel 4 is 0.5 mm, and the inlet structural angle α1 is 45°. Figure 3 and Figure 4 As shown, the outlet structural angle α2 is 64°, and the included angle β2 with the plane of the U-shaped cooling channel is 22°. The diameter Φ2 of the trailing edge cooling channel 6 is 0.8mm, the inlet structural angle α3 is 35°, the outlet structural angle α4 is 40°, and the included angle β1 with the plane of the U-shaped cooling channel is 20°.

Claims

1. A cooling channel for a turbine blade, characterized in that: including an inlet (1) and an outlet (2) at the bottom of the blade (7); A first main flow straight channel (3) and a second main flow straight channel (8) are provided in the blade (7), and the first main flow straight channel (3) and the second main flow straight channel (8) are respectively connected to the inlet (1) and the outlet (2); The first main flow straight channel (3) and the second main flow straight channel (8) are parallel to each other and are connected to form a U-shaped cooling channel via an arc-shaped pipe (5); A leading edge cooling branch channel (4) is provided at the connection between the first main flow straight channel (3) and the arc-shaped pipe (5); A trailing edge cooling branch channel (6) is provided at the connection between the second main flow straight channel (8) and the arc-shaped pipe (5); The leading edge cooling sub-channel (4) and the trailing edge cooling sub-channel (6) are respectively located in the leading edge tip and the trailing edge tip region of the blade (7); The leading edge cooling sub-channel (4) has a pipe diameter Φ3 of 0.5 mm, an inlet structural angle α1 of 45°, an outlet structural angle α2 of 64°, and an included angle β2 with the plane where the U-shaped cooling channel is located is 22°; the trailing edge cooling sub-channel (6) has a pipe diameter Φ2 of 0.8 mm, an inlet structural angle α3 of 35°, an outlet structural angle α4 of 40°, and an included angle β1 with the plane where the U-shaped cooling channel is located is 20°.

2. The cooling channel of a turbine blade according to claim 1, characterized in that: The leading edge cooling sub-channel (4) and the trailing edge cooling sub-channel (6) are both human ear-shaped cooling sub-channels.

3. The cooling channel of a turbine blade according to claim 2, characterized in that: The distance τ between the top of the U-shaped cooling channel and the blade tip is 2.75 mm, the distance d between the first main flow straight channel (3) and the second main flow straight channel (8) is 4.5 mm, and the diameter Φ1 of the U-shaped cooling channel is 1.5 mm.

Images