Air extraction opening structure for gas turbine casing

Abstract

An extraction opening structure for a gas turbine casing comprises the casing, a set of stator blade mounting grooves are formed in the casing, a stator blade is arranged in each stator blade mounting groove, an internal extraction opening is formed in the root of each stator blade mounting groove, and an external extraction opening casing inclined to the internal extraction opening is arranged at the top of each internal extraction opening. A group of stator blade mounting grooves are formed in the casing, a stator blade is arranged in each stator blade mounting groove, an internal extraction opening is formed in the root of each stator blade mounting groove, an external extraction opening inclined to the internal extraction opening is formed in the top of each internal extraction opening, and an extraction opening is formed in the casing at a blade root groove of each stator blade. According to the product, the mainstream area of the gas compressor is stable, so that the running safety of the gas turbine is improved.

Description

Technical Field

[0001] This utility model relates to the field of gas turbines, and in particular to an exhaust port structure for a gas turbine casing. Background Technology

[0002] Surge is a low-frequency, high-amplitude oscillation phenomenon that occurs during the operation of a gas turbine compressor due to unstable airflow. The root cause of surge is airflow separation and backflow resulting from the diffuser properties of the compressor blade channels. When the compressor inlet flow rate decreases or the inlet total temperature is too high, the compressor's operating point may enter an unstable region, thus triggering surge. Air extraction devices are a common method for addressing surge. A turbine ejector is a type of air extraction device, typically using a centrifugal fan as the extraction power source. Air enters the fan through the inlet and is ejected under the centrifugal force generated by the fan's high-speed rotation, creating negative pressure to extract the air. The extracted air is then mixed with the fluid and discharged from the turbine outlet.

[0003] • Air extraction function: The air extraction device reduces the volume of the working fluid in the system by extracting a portion of the air from the compressor outlet, thereby optimizing the system's adiabatic efficiency. In this process, the air extraction device is actually regulating the airflow state within the compressor.

[0004] • Reduced surge mechanism: By extracting some air, the evacuation device helps stabilize the airflow within the compressor, reducing surge caused by airflow separation and backflow. Simultaneously, the evacuation device also reduces overall temperature and pressure fluctuations at the compressor inlet, further reducing the likelihood of surge.

[0005] The existing gas turbine casing extraction devices have the following problems:

[0006] 1. Low reliability of the air extraction device: The air extraction device is prone to failure, which exacerbates the surge problem.

[0007] 2. The impact of air extraction on compressor performance: Although air extraction devices can reduce surge, air extraction will cause uneven airflow pressure distribution inside the compressor, which in turn affects its compression efficiency and stability. Utility Model Content

[0008] This utility model addresses the aforementioned shortcomings of the existing technology by providing an air extraction port structure for a gas turbine casing. This structure involves setting an air extraction port at the root of the blades of a gas turbine compressor, extracting a portion of the airflow to adjust the airflow state inside the compressor, optimizing the airflow distribution, solving the problem of uneven flow field near the compressor air extraction port, and making the airflow more evenly distributed on the blade surface to prevent surge.

[0009] The objective of this utility model is achieved through the following technical solution:

[0010] An air extraction port structure for a gas turbine casing includes a casing, a set of stationary blade mounting slots on the casing, a stationary blade in each stationary blade mounting slot, an internal air extraction port at the root of each stationary blade mounting slot, and an external air extraction port at the top of each internal air extraction port that is inclined to the internal air extraction port.

[0011] The internal air extraction port can be designed with various cross-sections according to the pipeline structure.

[0012] The axial width L2 of the internal air extraction port must not exceed the axial width of the gap between the moving and stationary blades, that is, it must not be opened at the top of the moving blade.

[0013] The axial width L1 of the internal air extraction port shall not be less than 1.5 times the diameter D of the air extraction hole.

[0014] The height H1 of the internal air extraction port shall not be less than 1.5 times the height H2 of the root groove of the stationary blade.

[0015] The circumferential position of the internal air extraction port is located at the junction of two adjacent stationary blades, and the axial distance T2 between adjacent internal air extraction ports is 1 / 3 to 1 / 2 of the axial distance T1 between two adjacent stationary blades.

[0016] The tilt angle α between the centerline of the external air extraction port and the horizontal direction of the air extraction port ranges from 30° to 150°.

[0017] Beneficial effects: Setting an air extraction port at the casing position of the blade root groove has the following benefits: 1. Optimizes airflow distribution: Air extraction at the blade root adjusts the airflow state inside the compressor, making the airflow more evenly distributed on the blade surface and reducing unstable phenomena such as eddies and backflow.

[0018] 2. Reduce airflow velocity: Extracting part of the airflow can reduce the airflow velocity inside the compressor, thereby reducing the impact and friction of the airflow on the blades and reducing the risk of blade wear and damage.

[0019] 3. Reduce airflow blockage: By optimizing airflow distribution and reducing airflow velocity, air extraction at the blade root can effectively reduce the occurrence of airflow blockage, thereby effectively reducing surge and improving the stability and efficiency of the compressor.

[0020] 4. Through extensive CFD calculations and flow field analysis, it was found that the stability of this exhaust port structure is improved by 5% compared with the structure that directly places the exhaust port on the casing, ensuring the stability of the compressor's main flow zone and thus improving the safety of gas turbine operation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the main view of the exhaust port structure of the gas turbine casing according to the present invention.

[0022] Figure 2 This is a schematic diagram of the exhaust port structure of the gas turbine casing according to the present invention, viewed from direction A.

[0023] Figure 3 This is a schematic diagram of the exhaust port structure of the gas turbine casing according to the present invention, viewed from direction B. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0025] refer to Figure 1 , 2 3. An air extraction port structure for a gas turbine casing, comprising a casing 150, a set of stationary blade mounting slots 160 on the casing 150, a stationary blade 110 in each stationary blade mounting slot 160, an internal air extraction port 130 at the root of each stationary blade mounting slot 160, and an external air extraction port 140 at the top of each internal air extraction port 130 that is inclined to the internal air extraction port 130.

[0026] The internal air extraction port 130 can be designed with various cross-sections according to the pipeline structure.

[0027] The axial width L2 of the internal air extraction port must not exceed the axial width of the gap between the moving and stationary blades, that is, it must not be opened at the top of the moving blade.

[0028] The axial width L1 of the internal air extraction port 130 shall not be less than 1.5 times the diameter D of the air extraction hole.

[0029] The height H1 of the internal air extraction port 130 shall not be less than 1.5 times the height H2 of the root groove of the stationary blade.

[0030] The circumferential position of the internal air extraction port 130 is located at the junction of two adjacent stationary blades, and the axial distance T2 between the air extraction ports of the adjacent internal air extraction ports 130 is 1 / 3 to 1 / 2 of the axial distance T1 between the two adjacent stationary blades.

[0031] The tilt angle α between the centerline of the external air extraction port 140 and the horizontal direction of the air extraction port ranges from 30° to 150°.

[0032] This device includes a casing 150, on which a set of stationary blade mounting slots 160 are provided. Each stationary blade 110 is located in each stationary blade mounting slot 160, and an internal exhaust port 130 is located at the bottom of each stationary blade mounting slot 160. The internal exhaust port 130 can be designed with various cross-sections according to the pipeline structure. Simulation analysis using CFD (Computational Fluid Dynamics) software revealed that the airflow blockage at the blade root is a serious problem. During compressor surge, the airflow exhibits low-frequency, high-amplitude oscillations along the compressor axis, usually due to airflow separation. When the compressor airflow is less than the design value, airflow separation occurs on the blade back surface, forming an unstable vortex boundary layer and developing into local stall. This local stall phenomenon can develop into several large local stall zones, eventually expanding to the entire compressor passage, causing passage blockage and severe airflow obstruction. To solve this problem, the exhaust device in this device is located at the blade root.

[0033] The axial width L1 of the internal air extraction port 130 can be designed to be any width, but it shall not be less than 1.5 times the diameter D of the extraction hole. The axial width L2 of the internal air extraction port shall not exceed the axial width of the gap between the moving and stationary blades, that is, it shall not be opened at the top of the moving blade. The height H1 of the internal air extraction hole of the internal air extraction port 130 shall not be less than 1.5 times the height H2 of the root groove of the stationary blade. The circumferential position of the internal air extraction port 130 is located at the junction of two adjacent stationary blades, and the axial distance T2 between adjacent air extraction ports of the internal air extraction port 130 is 1 / 3 to 1 / 2 of the axial distance T1 between two adjacent stationary blades. The design of the above air extraction port takes into account the strength requirements of the blades, avoids excessive damage to the blades, and meets the requirements of air extraction.

[0034] Each internal air extraction port 130 has an external air extraction port 140 at its top. The angle α between the centerline of the external air extraction port 140 and the horizontal direction of the air extraction port ranges from 30° to 150°.

[0035] The inclined design of the intake and exhaust ports can reduce the angle between the fluid at the injection port and the flow direction, thereby reducing mixing losses; optimize airflow distribution: the inclined intake and exhaust ports help to better guide the airflow, optimize the airflow distribution inside the compressor, and improve the compressor efficiency; adapt to the compressor structure: the compressor has a complex structure, and the inclined design can better adapt to the overall structure of the compressor, ensuring smooth intake and exhaust.

[0036] An extraction port is located at the root groove of the stationary blade in the casing. During gas turbine operation, gas is extracted according to the needs of the entire unit. A portion of the gas in the mainstream area first enters the internal extraction port, is rectified in a relatively large container, and then is delivered to the required location through the external extraction port. This has the following effects:

[0037] 1. Optimized airflow distribution: Air extraction at the blade root adjusts the airflow state inside the compressor, making the airflow more evenly distributed on the blade surface and reducing unstable phenomena such as eddies and backflow.

[0038] 2. Reduce airflow velocity: Extracting part of the airflow can reduce the airflow velocity inside the compressor, thereby reducing the impact and friction of the airflow on the blades and reducing the risk of blade wear and damage.

[0039] 3. Reduce airflow blockage: By optimizing airflow distribution and reducing airflow velocity, air extraction at the blade root can effectively reduce the occurrence of airflow blockage, thereby effectively reducing surge and improving the stability and efficiency of the compressor.

[0040] This invention relates to a gas turbine exhaust port structure designed to prevent the impact of compressor-positioned exhaust on the stability of the compressor's mainstream flow. Extensive CFD calculations and flow field analyses have shown that this exhaust port structure improves stability by 5% compared to structures where the exhaust port is directly located on the casing, ensuring the stability of the compressor's mainstream flow and thus enhancing the safety of gas turbine operation.

Claims

1. A vent structure for a gas turbine casing, characterized in that: The device includes a casing (150), on which a set of stationary blade mounting slots (160) are provided. Each stationary blade mounting slot (160) contains a stationary blade (110). Each stationary blade mounting slot (160) has an internal air extraction port (130) at its root and an external air extraction port (140) at its top that is inclined to the internal air extraction port (130).

2. The extraction port structure for a gas turbine casing according to claim 1, characterized in that: The internal air extraction port (130) can be designed with various cross sections according to the pipeline structure.

3. The extraction port structure for a gas turbine casing according to claim 1, characterized in that: The axial width L (2) of the internal air extraction port (130) shall not exceed the axial width of the gap between the moving and stationary blades, that is, it shall not be opened at the top of the moving blade.

4. The extraction port structure for a gas turbine casing according to claim 1, characterized in that: The axial width L1 of the internal air extraction port (130) shall not be less than 1.5 times the diameter D of the air extraction hole.

5. The extraction port structure for a gas turbine casing according to claim 1, characterized in that: The height H1 of the internal air extraction port (130) shall not be less than 1.5 times the height H2 of the root groove of the stationary blade.

6. The extraction port structure for a gas turbine casing according to claim 1, characterized in that: The circumferential position of the internal air extraction port (130) is located at the junction of two adjacent stationary blades, and the axial distance T2 between adjacent internal air extraction ports (130) is 1 / 3 to 1 / 2 of the axial distance T2 between two adjacent stationary blades.

7. The extraction port structure for a gas turbine casing according to claim 1, characterized in that: The angle α between the centerline of the external air extraction port (140) and the horizontal direction of the air extraction port ranges from 30° to 150°.

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