Mixed-flow compressor and flow mixing method

Abstract

The invention discloses a mixed-flow compressor and a mixed-flow method. At present, due to the adoption of a two-stage centrifugal compressor, the efficiency is reduced due to too many turning of a flow channel, and meanwhile, complexity is caused when double shafts are adopted. The multi-stage centrifugal compressor comprises a multi-stage axial flow compressor A and a single-stage centrifugal compressor B, wherein the multi-stage axial flow compressor and the single-stage centrifugal compressor share the same rotor; the multi-stage axial-flow compressor comprises an air inlet chamber, an axial-flow compressor casing and a compressor rotor, a plurality of groups of axial-flow compressor moving blades are fixed on the outer ring surface of the compressor rotor, a plurality of groups of compressor guide blade assemblies are fixed in the axial-flow compressor casing, and the axial-flow compressor moving blades and the compressor guide blade assemblies are arranged at intervals; a plurality of groups of rotor wheel discs are fixed in the compressor rotor; the centrifugal wheel disc of the single-stage centrifugal compressor is connected with the last-stage rotor wheel disc of the multi-stage axial flow compressor through a flange; and the centrifugal compressor casing is connected with the axial flow compressor casing through a flange. The invention is applied to the mixed-flow compressor.

Description

Technical Field

[0001] The invention relates to a mixed flow compressor and a mixed flow method. Background Art

[0002] As the pressure ratio of the compressor of small and medium flow engines and gas turbines increases, the channel height of the rear stage becomes smaller and smaller. When the entire compressor adopts axial flow stages, the efficiency of the rear stage will be very low. If a two-stage centrifugal compressor is used, too many turns in the flow channel will lead to a decrease in efficiency, and there will be complex problems when using dual shafts. Summary of the invention

[0003] The object of the present invention is to solve the above-mentioned problems, thereby providing a mixed flow compressor and a mixed flow method.

[0004] The above purpose is achieved through the following technical solutions: A mixed flow compressor comprises a multi-stage axial flow compressor and a single-stage centrifugal compressor, wherein the multi-stage axial flow compressor and the single-stage centrifugal compressor share the same rotor; The multi-stage axial compressor comprises an air inlet chamber, an axial compressor casing and a compressor rotor, a plurality of groups of axial compressor rotor blades are fixed on the outer ring surface of the compressor rotor, a plurality of groups of compressor guide vane assemblies are fixed in the axial compressor casing, and the axial compressor rotor blades and the compressor guide vane assemblies are arranged at intervals; The single-stage centrifugal compressor comprises a centrifugal impeller, an impeller cover, a centrifugal compressor casing and a centrifugal wheel; A plurality of rotor discs are fixed in the compressor rotor, and the centrifugal discs of the single-stage centrifugal compressor are connected to the rotor discs of the last stage of the multi-stage axial flow compressor via flanges; The centrifugal compressor casing is connected to the axial compressor casing via a flange.

[0005] The mixed flow compressor described herein, the single-stage centrifugal compressor comprises a centrifugal impeller, an impeller cover, a centrifugal compressor casing and a centrifugal wheel disc, the centrifugal impeller is fixed on the centrifugal wheel disc, the impeller cover and the centrifugal blade clearance are matched, the impeller cover and the centrifugal compressor casing are fixed by bolts, and the impeller cover mating surface is provided with a labyrinth sealing tooth structure.

[0006] A mixed flow compressor, wherein the compressor guide vane assembly comprises an outer ring, compressor stator blades, an inner ring and an air seal arc; the outer ring is provided with dovetail grooves, the number of dovetail grooves of each stage of the outer ring is equal to the number of compressor stator blades, and the compressor stator blades are fixed on the dovetail grooves; the air seal arc is connected to the inner ring; the inner ring and the compressor stator blades are fixed by rivets, and the outer ring is circumferentially inserted into a matching groove opened in the compressor casing.

[0007] In the mixed flow compressor, the compressor rotor is in the form of a drum, the compressor rotor is connected to the first-stage / last-stage rotor disc via a flange, and is welded to the intermediate-stage disc via an electron beam.

[0008] In the mixed flow compressor, the compressor casing comprises a guide vane casing and an intermediate casing, and the vane casing and the intermediate casing are connected by bolts.

[0009] In the mixed flow compressor, the axial flow compressor impeller and the axial flow compressor casing are clearance matched, and the clearance d is 0.3-0.5mm.

[0010] In the mixed flow compressor, the compressor rotor is provided with a labyrinth seal tooth structure, and the labyrinth seal teeth and the air seal arc form a seal together.

[0011] In the mixed flow compressor, the axial flow compressor moving blades and the compressor stationary blades are both titanium alloy blades.

[0012] A mixed flow method for a mixed flow compressor, the method comprising the following steps: (1) The air flow is first guided by a row of inlet guide vanes, then accelerated by a row of moving blades, and then decelerated in the stator blade channel, converting the kinetic energy in the rotor into static pressure energy. Then, the air flow is alternately arranged in a row of moving blades and a row of stator blades. This process is repeated in multiple stages of blades until the total pressure ratio reaches the required level. (2) After the air is drawn out from the axial compressor and enters the centrifugal compressor, the airflow is further compressed and discharged after passing through the blade diffuser in the diffuser section, which is to reduce the air velocity and increase the air static pressure; the outlet guide vane assembly is provided with guide vanes for the airflow to flow out in the radial direction. Since the airflow has a very high airflow velocity after coming out of the working impeller, it also has a large kinetic energy, which accounts for about 25%-50% of the impeller processing volume. The outlet guide vane assembly is provided with guide vanes for the airflow to flow out in the radial direction. Beneficial Effects

[0013] 1. The present invention adopts a mixed flow compressor combining axial flow and centrifugal flow, which can combine the characteristics of smooth flow path, high efficiency, adaptability to larger inlet flow of the axial flow stage and adaptability to small flow, wide working range, few parts and high reliability of the centrifugal stage.

[0014] 2. The mixed flow multi-stage compressor of the present invention is used for gas turbines, which can achieve high pressure ratio and high efficiency at a small flow rate. The axial flow compressor and the centrifugal compressor share a rotor, and the overall structure is simple, easy to process, and suitable for popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the structure of a multi-stage axial flow compressor; Figure 3 It is a schematic diagram of the structure of a single-stage centrifugal compressor; Figure 4 It is a schematic diagram of the structure of the compressor guide vane assembly; Figure 5 It is a schematic diagram of the labyrinth seal tooth structure of the compressor rotor; Figure 6 1. It is a schematic diagram of the clearance between the axial flow compressor blades and the axial flow compressor casing; Figure 7 It is a schematic diagram of the structure of the axial flow compressor casing; Figure 8 It is a schematic diagram of the connection between the centrifugal wheel disc and the rotor wheel disc; Fig. 9 It is a schematic diagram of the structure of the expansion section of a single-stage centrifugal compressor; Fig.10 is a schematic diagram of the blade diffuser structure; Fig.11 yes Figure 3 Enlarged view of part C; In the figure: A, multi-stage axial compressor; B, single-stage centrifugal compressor; 1, air inlet chamber; 2, axial compressor casing; 3, compressor rotor; 4, inlet guide vane; 5, axial compressor moving blade; 6, compressor guide vane assembly; 7, rotatable guide vane; 8, rotor wheel; 10, centrifugal wheel; 11, centrifugal blade; 12, impeller cover; 13, centrifugal compressor casing; 14, diffuser section; 15, outlet guide vane assembly; 16, back seal; 21, outer ring; 22, compressor stator; 23, inner ring; 24, air seal arc; 25, labyrinth seal tooth; 51, guide vane casing; 52, intermediate casing; 53, bolts; 71, blade diffuser; 72, outer wall; 73, inner wall; 81, outlet guide vane; 82, side wall. DETAILED DESCRIPTION

[0016] Reference Figure 1-Figure 11 , a mixed flow compressor, comprising a multi-stage axial flow compressor A and a single-stage centrifugal compressor B, wherein the multi-stage axial flow compressor and the single-stage centrifugal compressor share the same rotor; Air enters the axial flow section of the compressor through the intake chamber, is compressed and then enters the centrifugal section, where it is further compressed and supplied to the combustion chamber; The mixed flow compressor adopts the combination of axial flow and centrifugal flow, which can combine the characteristics of smooth flow path, high efficiency, adaptability to larger inlet flow of the axial flow stage and adaptability to small flow, wide working range, few parts and high reliability of the centrifugal stage; The multi-stage axial compressor comprises an air inlet chamber 1, an axial compressor casing 2 and a compressor rotor 3, a plurality of groups of axial compressor blades 5 are fixed on the outer ring surface of the compressor rotor, a plurality of groups of compressor guide vane assemblies 6 are fixed in the axial compressor casing, and the axial compressor blades and the compressor guide vane assemblies are arranged at intervals; The multi-stage axial flow compressor first has one row of inlet guide vanes along the air flow direction, and then one row of moving blades and one row of stationary blades are arranged alternately, and all blades are evenly arranged at a certain installation angle along the circumferential direction; The multi-stage axial flow compressor has a meridian flow channel structure composed of the end walls of nine-stage dynamic and static blades. The meridian flow channel is formed in a form similar to equal outer diameter. The upper end wall is horizontal, and the upper and lower end walls of the blades are designed to form a certain angle with the center line. The upper and lower meridian flow channels form a certain reasonable angle with the center line, ensuring the aerodynamic efficiency of the nine-stage high-pressure compressor at 13,300 revolutions per minute.

[0017] A multi-stage axial flow compressor first has a row of inlet guide vanes along the air flow direction, and then a row of moving blades / a row of stationary blades are arranged alternately. First, a row of inlet guide vanes are used to guide the air, and then a row of moving blades accelerates the air, and then decelerates in the stationary blade channel to convert the kinetic energy in the rotor into static pressure energy. This process is repeated in multiple stages of blades until the total pressure ratio reaches the requirement.

[0018] The inlet guide vanes of the multi-stage axial flow compressor adopt a variable angle design. The inlet guide vanes can expand and stabilize the compressor and reduce the degree of distortion of the compressor. Through the variable angle design, the airflow passing through the inlet guide vanes generates pre-swirl, so that the angle of attack when entering the rotor is reduced, and the angle of the airflow entering the first stage of the compressor is changed as the speed changes, so as to improve the performance of the non-design state, suppress the airflow separation phenomenon, and improve the compressor working condition; The first and second stage compressor stators also adopt a variable angle design, which can increase the stable operating margin of the compressor, ensure that the airflow passes through the compressor at an approximately constant axial speed, prevent air flow loss and compressor surge, improve the low-load performance of the compressor, better match the performance of various components of the gas turbine, control the turbine exhaust temperature, and improve the combined cycle efficiency.

[0019] In each stage of the multi-stage axial flow compressor, a plurality of rotor disks and axial flow compressor moving blades are evenly arranged along the circumferential direction, and the two are connected by a blade root mortise and tenon groove, and the blade root shape can be a dovetail type, a fork type, or a tooth type; The single-stage centrifugal compressor comprises a centrifugal impeller 11, an impeller cover 12, a centrifugal compressor casing 13 and a centrifugal wheel 10; A plurality of rotor discs 8 are fixed in the compressor rotor, and the centrifugal disc 10 of the single-stage centrifugal compressor is connected to the rotor disc of the last stage of the multi-stage axial flow compressor through a flange; The centrifugal compressor casing is connected to the axial compressor casing via a flange.

[0020] The centrifugal compressor has the characteristics of small size and high single-stage compression ratio. It combines the axial flow compressor and the centrifugal compressor. Through a common rotor shaft, the intake air is first pressurized and deflected in the axial flow compressor, and then enters the centrifugal compressor. Under small flow conditions, a larger deflection of the intake angle can be achieved, thereby achieving high flow and high compression ratio in a small space.

[0021] The single-stage centrifugal compressor comprises a centrifugal impeller 11, an impeller cover 12, a centrifugal compressor casing 13 and a centrifugal wheel disc 10, a centrifugal impeller is fixed on the centrifugal wheel disc, the centrifugal blades 11 and the centrifugal wheel disc 10 are integrally forged, the impeller cover and the centrifugal blades are gap-matched, the impeller cover and the centrifugal compressor casing are fixed by bolts, and the mating surface of the impeller cover is provided with a labyrinth sealing tooth structure.

[0022] The compressor guide vane assembly comprises an outer ring 21, a compressor vane 22, an inner ring 23 and an air seal arc 24; the outer ring is provided with dovetail grooves, the number of dovetail grooves of each stage of the outer ring is equal to the number of compressor vanes, and the compressor vanes are fixed on the dovetail grooves; the air seal arc is connected to the inner ring; the inner ring and the compressor vanes are fixed by rivets, and the outer ring is circumferentially inserted into a matching groove opened in the compressor casing; The design of grooves on the casing and the installation of the outer ring in the grooves greatly reduce the installation burden. At the same time, in terms of processing technology, the compressor stators of each stage have the same size and the same length of compressor stator blades, making it more convenient for actual production and manufacturing; The compressor rotor is in the form of a drum, and is connected to the first-stage / last-stage rotor disc via a flange, and is welded to the intermediate-stage disc via an electron beam.

[0023] The compressor casing includes a guide vane casing 51 and an intermediate casing 52 , and the vane casing 51 and the intermediate casing are connected by bolts 53 .

[0024] The axial flow compressor impeller and the axial flow compressor casing are clearance matched, and the clearance d is 0.3-0.5mm.

[0025] The compressor rotor is provided with a labyrinth seal tooth structure. The labyrinth seal tooth 25 forms a seal together with the air seal arc 24 to prevent air leakage between compressor stages and ensure aerodynamic efficiency. At the same time, the sealing effect can be enhanced by the multi-stage labyrinth seal tooth structure. The compressor rotor is equipped with a labyrinth seal tooth structure, which can effectively isolate the cylinder temperature and prevent hot combustion gas from entering the cylinder, thereby achieving the effect of sealing the cylinder, improving the sealing of the high-pressure compressor wheel, and thus effectively increasing the life of the turbine cylinder, ensuring the safe and efficient operation of the gas turbine.

[0026] The axial flow compressor moving blades and compressor stationary blades are both titanium alloy blades.

[0027] The single-stage centrifugal compressor diffuser section includes an inner wall 73 and an outer wall 72, with a blade diffuser 71 in the middle. After the air comes out of the working impeller, it has a very high airflow velocity, that is, it has a large kinetic energy, which accounts for about 25%-50% of the impeller processing volume. The diffuser section is provided with a blade diffuser to reduce the air flow velocity and increase the air static pressure; the outlet guide vane assembly is provided with guide vanes for the airflow to flow out radially.

[0028] An outlet guide vane assembly is provided above the blade diffuser. The outlet guide vane 81 is welded to the end walls 82 on both sides and fixed to the diffuser section end cover by bolts.

[0029] The invention proposes a mixed flow multi-stage compressor for a gas turbine, which can achieve high pressure ratio and high efficiency at a small flow rate. The axial flow compressor and the centrifugal compressor share a rotor, and the overall structure is simple, easy to process, and suitable for popularization and use.

[0030] A mixed flow method for a mixed flow compressor, the method comprising the following steps: (1) The air flow is first guided by a row of inlet guide vanes, then accelerated by a row of moving blades, and then decelerated in the stator blade channel, converting the kinetic energy in the rotor into static pressure energy. Then, the air flow is alternately arranged in a row of moving blades and a row of stator blades. This process is repeated in multiple stages of blades until the total pressure ratio reaches the required level. (2) After the air is drawn out from the axial compressor and enters the centrifugal compressor, the airflow is further compressed and discharged after passing through the blade diffuser in the diffuser section, which is to reduce the air velocity and increase the air static pressure; the outlet guide vane assembly is provided with guide vanes for the airflow to flow out in the radial direction. Since the airflow has a very high airflow velocity after coming out of the working impeller, it also has a large kinetic energy, which accounts for about 25%-50% of the impeller processing volume. The outlet guide vane assembly is provided with guide vanes for the airflow to flow out in the radial direction.

Claims

1. A mixed flow compressor, characterized in that: It comprises a multi-stage axial flow compressor and a single-stage centrifugal compressor, wherein the multi-stage axial flow compressor and the single-stage centrifugal compressor share the same rotor; The multi-stage axial compressor comprises an air inlet chamber, an axial compressor casing and a compressor rotor, a plurality of groups of axial compressor rotor blades are fixed on the outer ring surface of the compressor rotor, a plurality of groups of compressor guide vane assemblies are fixed in the axial compressor casing, and the axial compressor rotor blades and the compressor guide vane assemblies are arranged at intervals; The single-stage centrifugal compressor comprises a centrifugal impeller, an impeller cover, a centrifugal compressor casing and a centrifugal wheel; A plurality of rotor discs are fixed in the compressor rotor, and the centrifugal discs of the single-stage centrifugal compressor are connected to the rotor discs of the last stage of the multi-stage axial flow compressor via flanges; The centrifugal compressor casing is connected to the axial compressor casing via a flange.

2. A mixed flow compressor according to claim 1, characterized in that: The single-stage centrifugal compressor comprises a centrifugal impeller, an impeller cover, a centrifugal compressor casing and a centrifugal wheel disc, the centrifugal impeller is fixed on the centrifugal wheel disc, the impeller cover is clearance-matched with the centrifugal blades, the impeller cover is fixed to the centrifugal compressor casing by bolts, and the mating surface of the impeller cover is provided with a labyrinth sealing tooth structure.

3. A mixed flow compressor according to claim 1, characterized in that: The compressor guide vane assembly comprises an outer ring, compressor stator blades, an inner ring and an air seal arc; the outer ring is provided with dovetail grooves, the number of dovetail grooves of each stage of the outer ring is equal to the number of compressor stator blades, and the compressor stator blades are fixed on the dovetail grooves; the air seal arc is connected to the inner ring; the inner ring and the compressor stator blades are fixed by rivets, and the outer ring is circumferentially inserted into a matching groove opened in the compressor casing.

4. A mixed flow compressor according to claim 1, characterized in that: The compressor rotor is in the form of a drum, and is connected to the first-stage / last-stage rotor disc via a flange, and is welded to the intermediate-stage disc via an electron beam.

5. A mixed flow compressor according to claim 1, characterized in that: The compressor casing comprises a guide vane casing and an intermediate casing, and the vane casing and the intermediate casing are connected by bolts.

6. A mixed flow compressor according to claim 1, characterized in that: The axial flow compressor impeller and the axial flow compressor casing are clearance matched, and the clearance d is 0.3-0.5mm.

7. A mixed flow compressor according to claim 1, characterized in that: The compressor rotor is provided with a labyrinth seal tooth structure, and the labyrinth seal teeth form a seal together with the air seal arc.

8. A mixed flow compressor according to claim 3, characterized in that: The axial flow compressor moving blades and compressor stationary blades are both titanium alloy blades.

9. A mixed flow method for a mixed flow compressor according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: (1) The air flow is first guided by a row of inlet guide vanes, then accelerated by a row of moving blades, and then decelerated in the stator blade channel, converting the kinetic energy in the rotor into static pressure energy. Then, the air flow is alternately arranged in a row of moving blades and a row of stator blades. This process is repeated in multiple stages of blades until the total pressure ratio reaches the required level. (2) After the air is drawn out from the axial compressor and enters the centrifugal compressor, the airflow is further compressed and discharged after passing through the blade diffuser in the diffuser section, which is to reduce the air velocity and increase the air static pressure; the outlet guide vane assembly is provided with guide vanes for the airflow to flow out in the radial direction. Since the airflow has a very high airflow velocity after coming out of the working impeller, it also has a large kinetic energy, which accounts for about 25%-50% of the impeller processing volume. The outlet guide vane assembly is provided with guide vanes for the airflow to flow out in the radial direction.

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