Hub cooling device coupled with inlet vortex and design method

Abstract

The invention belongs to the technical field of gas turbine engines, and particularly relates to a hub cooling device coupled with inlet vortexes and a design method. Comprising an air film cooling jet hole formed in a hub plate in a channel between two adjacent blades, and a swirler is arranged on the upstream of a stationary point of the front edge of an inlet blade. The air film cooling device has the beneficial effects that the interaction between inlet vortexes and cold air is utilized, so that the air film cooling track can cover more hub areas. The air film holes are round holes, and the hub cooling effect of the air film holes can be improved compared with the prior art after inlet vortexes are added at proper positions.

Description

Technical Field

[0001] The invention belongs to the technical field of gas turbine engines, and in particular relates to a hub cooling device coupled with an inlet vortex and a design method thereof. Background Art

[0002] A turbine engine consists of a compressor, a combustion chamber, and a turbine. The gas is compressed by the compressor to form high-pressure gas, which is then mixed with fuel and burned in the combustion chamber to form high-temperature and high-pressure combustion gas. This combustion gas passes through the turbine and does work on the turbine, driving the rotor to rotate and driving the compressor to work.

[0003] The turbine consists of a hub, blades and a casing. In recent years, the temperature of the gas at the combustion chamber outlet has gradually increased. While the turbine's working capacity has been improved, it has also brought about severe thermal corrosion problems. In engineering, technologies such as film cooling can be used to cool the end wall surface. The gas used for cooling comes from the compressor outlet, so that the gas at the combustion chamber outlet that participates in the work of the turbine is reduced, sacrificing part of the gas's working capacity in exchange for the cooling protection of the turbine end wall. Therefore, how to achieve better cooling effect with less gas has become the main research direction in recent years.

[0004] Air film cooling refers to the technology of delivering cold air to the end wall that needs cooling through air film holes, gaps, etc. Figure 1 The figure shows the geometrical schematic diagram of the hub air film hole used in the present invention. After the cold air is ejected, a thin film will be formed on the end wall surface and separate the end wall from the high-temperature fluid, thereby preventing the wall surface from being corroded. Cold air is often transported by air film holes. Air film cooling first used circular holes for cooling. In order to allow more cold air to adhere to the wall surface, the circular holes are also changed to fan-shaped holes and crescent holes. There is also a solution of using double jet holes to improve the cooling effect.

[0005] Most of these solutions start from the flow structure of the oblique hole jet to improve the film cooling effect, without considering the interaction between the jet and the turbine secondary flow. The inlet boundary layer will produce two vortices with opposite rotation directions due to the stagnation effect of the leading edge of the blade. They are shaped like horseshoes and are therefore collectively called horseshoe vortices. The fluid between the horseshoe vortex and the blade is impacted by the downwash of the horseshoe vortex; while the fluid between adjacent horseshoe vortices is lifted off the hub wall by the upwash. In addition, the hub cross flow will be generated due to the influence of the circumferential pressure gradient. These secondary flows have an adverse effect on hub cooling. Figure 4 The blade horseshoe vortex structure and its induced vortex flow structure. These flow structures are more complex than the channel flow and will also significantly affect the film cooling effect.

[0006] There is a certain jet angle between the film hole and the hub. Due to the jet effect, part of the cold air enters the mainstream after being ejected, and the remaining cold air adheres to the hub. Due to the pressure gradient between the pressure surface and the suction surface of adjacent blades, there is a hub cross flow flowing circumferentially on the hub wall. Under the action of the hub cross flow, the cold air in the mainstream and the cold air attached to the hub are stretched circumferentially. In addition, when the film hole is located between the horseshoe vortices of adjacent blades, it will be affected by the horseshoe vortex upwash, and the cold air in the mainstream will move further away from the hub. It is difficult for the cold air in the mainstream to participate in the cooling of the hub, so the cooling effect is significantly reduced. Summary of the invention

[0007] The purpose of the present invention is to provide a hub cooling device coupled with an inlet vortex and a design method, which can control the hub secondary flow and jet cooling air through the inlet vortex to improve the cooling effect of the turbine hub and extend the engine life.

[0008] The technical solution of the present invention is as follows: a hub cooling device coupled with an inlet vortex comprises a film cooling jet hole opened on a hub plate in a channel between two adjacent blades, and a swirler is arranged upstream of the stagnation point of the leading edge of the inlet blade.

[0009] The air film cooling jet hole is a circular hole.

[0010] A swirler is arranged at the 1 / 4 channel position on the pressure surface side upstream of the stagnation point of the leading edge of the inlet blade.

[0011] The cyclone is a crownless cyclone, comprising 12 blades with a rotation angle of 30°, and the rotation direction of the generated vortex is opposite to the rotation direction of the horseshoe vortex pressure support.

[0012] The diameter d of the cyclone is 13% of the axial chord length, the thickness w is 8.7% of the axial chord length, and the distance between the center of the cyclone and the wall is 8.7% of the axial chord length.

[0013] A design method for a hub cooling device coupled with an inlet vortex comprises the following steps:

[0014] Step 1: Perform an oil flow display test under uniform inlet conditions to obtain the range of the hub area affected by the horseshoe vortex, and set the film cooling jet holes in the hub area affected by the horseshoe vortex;

[0015] Step 2: The inlet area is evenly divided into four parts in the circumferential direction, wherein the vortex center generated by the phase swirler located upstream of the blade leading edge impacts the stagnation point of the blade leading edge;

[0016] Step 3: Fix the swirler at a phase close to the pressure surface of the blade to generate a vortex, which can increase the air film coverage area of ​​the hub.

[0017] The beneficial effect of the present invention is that the interaction between the inlet vortex and the cold air is utilized so that the air film cooling track can cover more wheel hub areas. The air film hole is a circular hole, and after adding the inlet vortex at the appropriate position, the wheel hub cooling effect of the air film hole can be improved compared with the existing situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the positions of film cooling jet holes in a hub cooling device coupled with an inlet vortex provided by the present invention;

[0019] Figure 2 A three-dimensional schematic diagram of an inlet swirler in a hub cooling device coupled with an inlet vortex provided by the present invention;

[0020] Figure 3 It is the side view of the inlet cyclone and the cyclone parameters-test;

[0021] Figure 4 The horseshoe vortex structure and the vortex structure induced by the horseshoe vortex under uniform inlet conditions - numerical simulation;

[0022] Figure 5 This is the inlet vortex velocity cloud map - numerical simulation;

[0023] Figure 6 The cloud diagram of hub adiabatic cooling efficiency in the blade channel under uniform inlet conditions - numerical simulation;

[0024] Figure 7 This is a cloud diagram of the adiabatic cooling efficiency of the hub in the blade channel under vortex inlet conditions - numerical simulation.

[0025] In the figure: 1 blade, 2 channel inner hub plate, 3 film cooling jet hole, 4 swirler. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 , Figure 2 and Figure 3 A hub cooling device coupled with an inlet vortex is shown, comprising a film cooling jet hole 3 provided on a hub plate in a channel between two adjacent blades 1. In an embodiment of the present invention, the film cooling jet holes 3 are arranged in two rows near the blade tip, with multiple holes in each row. The film cooling jet holes 3 are circular holes. A swirler 4 is provided at the 1 / 4 channel position on the upstream pressure surface side of the leading edge stagnation point of the inlet blade 1. The swirler is provided to improve the cooling effect of the hub with the film cooling jet hole 3. The swirler 4 is a crownless swirler, comprising 12 blades with a rotation angle of 30°, and the rotation direction of the vortex generated is opposite to the rotation direction of the horseshoe vortex pressure branch. Figure 3 The diameter d of the middle cyclone is 13% of the axial chord length, the thickness w is 8.7% of the axial chord length, and the distance between the center of the cyclone 4 and the wall is 8.7% of the axial chord length.

[0028] A design method for a hub cooling device coupled with an inlet vortex comprises the following steps:

[0029] Step 1: Carry out an oil flow display test under uniform inlet conditions to obtain the range of the hub area affected by the horseshoe vortex. Set the film cooling jet holes in the hub area affected by the horseshoe vortex.

[0030] Step 2: The inlet area is evenly divided into four parts in the circumferential direction, in which the vortex center generated by the phase swirler located upstream of the blade leading edge impacts the stagnation point of the blade leading edge.

[0031] use Figure 2 The swirler shown induces vortex and is fixed at the 1 / 4 channel position of the pressure surface upstream of the inlet blade stagnation point. Figure 3 As shown, the diameter (d) of the cyclone is 13% of the axial chord length, the thickness (w) is 8.7% of the axial chord length, and the distance between the center of the cyclone and the wall is 8.7% of the axial chord length.

[0032] The numerical simulation uses Rankine vortex to simulate the flow field generated by the cyclone in the test. The rotation direction of the inlet vortex is opposite to the horseshoe vortex pressure support. The inlet vortex radius is 6.5% of the axial chord length, and the vortex center is 8.7% of the axial chord length from the hub wall. A cylindrical coordinate system is established at the vortex center, with the axial direction parallel to the inlet mainstream direction. The velocity-related parameters of the inlet vortex in the numerical calculation are as follows:

[0033]

[0034] Among them, V in V is the inlet velocity under uniform inlet conditions. θ is the inlet tangential velocity in the cylindrical coordinate system, V s is the flow velocity, the radial velocity is 0, k is the correlation factor between the tangential velocity and the axial velocity, k = 0.4. The numerical calculation compares the adiabatic cooling efficiency of the hub in the channel under the above vortex inlet and uniform inlet conditions. Figure 6 and Figure 7 shown. Figure 7 The air film cooling trajectory under the condition of medium vortex inlet is closer to the mainstream direction. The air film coverage area of ​​the wheel hub is increased.

[0035] Step 3: Fix the swirler designed above at a phase close to the pressure surface of the blade to generate a vortex, thereby increasing the air film coverage area of ​​the hub.

Claims

1. A hub cooling device coupled with an inlet vortex, characterized in that: The invention comprises an air film cooling jet hole opened on a hub plate in a channel between two adjacent blades, and a swirler is arranged upstream of a stagnation point at the leading edge of an inlet blade.

2. A hub cooling device coupled with an inlet vortex as claimed in claim 1, characterized in that: The air film cooling jet hole is a circular hole.

3. A hub cooling device coupled with an inlet vortex as claimed in claim 1, characterized in that: A swirler is arranged at the 1 / 4 channel position on the pressure surface side upstream of the stagnation point of the leading edge of the inlet blade.

4. A hub cooling device coupled with an inlet vortex as claimed in claim 1, characterized in that: The cyclone is a crownless cyclone, comprising 12 blades with a rotation angle of 30°, and the rotation direction of the generated vortex is opposite to the rotation direction of the horseshoe vortex pressure support.

5. A hub cooling device coupled with an inlet vortex as claimed in claim 3 or 4, characterized in that: The diameter d of the cyclone is 13% of the axial chord length, the thickness w is 8.7% of the axial chord length, and the distance between the center of the cyclone and the wall is 8.7% of the axial chord length.

6. A design method for a hub cooling device coupled with an inlet vortex, characterized in that: The steps include: Step 1: Perform an oil flow display test under uniform inlet conditions to obtain the range of the hub area affected by the horseshoe vortex, and set the film cooling jet holes in the hub area affected by the horseshoe vortex; Step 2: The inlet area is evenly divided into four parts in the circumferential direction, wherein the vortex center generated by the phase swirler located upstream of the blade leading edge impacts the stagnation point of the blade leading edge; Step 3: Fix the swirler at a phase close to the pressure surface of the blade to generate a vortex, which can increase the air film coverage area of ​​the hub.

Images