CN108386389B - Centrifugal compressor diffuser structure with blades, casing and hub fused - Google Patents

Centrifugal compressor diffuser structure with blades, casing and hub fused Download PDF

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Publication number
CN108386389B
CN108386389B CN201810128459.8A CN201810128459A CN108386389B CN 108386389 B CN108386389 B CN 108386389B CN 201810128459 A CN201810128459 A CN 201810128459A CN 108386389 B CN108386389 B CN 108386389B
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China
Prior art keywords
diffuser
radial
axial
blade
casing
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CN201810128459.8A
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CN108386389A (en
Inventor
韩戈
龚建波
郭磊
胡春艳
穆勇
卢新根
徐纲
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Institute of Engineering Thermophysics of CAS
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Institute of Engineering Thermophysics of CAS
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/40Casings; Connections of working fluid
    • F04D29/42Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/44Fluid-guiding means, e.g. diffusers
    • F04D29/441Fluid-guiding means, e.g. diffusers especially adapted for elastic fluid pumps
    • F04D29/444Bladed diffusers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02CGAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C3/00Gas-turbine plants characterised by the use of combustion products as the working fluid
    • F02C3/04Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor
    • F02C3/08Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor the compressor comprising at least one radial stage
    • F02C3/085Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor the compressor comprising at least one radial stage the turbine being of the radial-flow type (radial-radial)
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/40Casings; Connections of working fluid
    • F04D29/42Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/44Fluid-guiding means, e.g. diffusers
    • F04D29/46Fluid-guiding means, e.g. diffusers adjustable
    • F04D29/462Fluid-guiding means, e.g. diffusers adjustable especially adapted for elastic fluid pumps
    • F04D29/464Fluid-guiding means, e.g. diffusers adjustable especially adapted for elastic fluid pumps adjusting flow cross-section, otherwise than by using adjustable stator blades

Abstract

The invention discloses a centrifugal compressor diffuser structure with blades fused with a casing and a hub, which belongs to the technical field of small and medium-sized aero-engine compressors and is characterized in that a radial diffuser and an axial diffuser are connected into a whole, the front edge of the radial diffuser is designed to be a sharp edge to reduce loss and the outer diameter of the diffuser, and the blades are further fused with the casing and the hub of the diffuser to reduce the distortion degree of the blades of the diffuser, so that the blades are convenient to design and process. The invention can be directly applied to small-sized aeroengines, and can reduce the outer diameter of the engine and improve the thrust-weight ratio of the engine on the premise of not increasing the processing cost and not reducing the performance of the air compressor.

Description

Centrifugal compressor diffuser structure with blades, casing and hub fused
Technical Field
The invention belongs to the technical field of small and medium-sized aircraft engine compressors, relates to a diffuser structure of a centrifugal compressor, and particularly relates to a diffuser structure of a centrifugal compressor with blades, a casing and a hub fused together, which can reduce the maximum outer diameter of the diffuser under the condition that the diameter of an inlet of the diffuser is not changed, and simultaneously reduce the distortion degree of a pressure surface and a suction surface of the blades of the diffuser.
Background
The centrifugal compressor has the advantages of high single-stage pressure ratio, wide working range, simple structure, high reliability and the like, and is widely applied to small gas turbines and small and medium-sized aeroengines. Along with the improvement of the pressure ratio of the centrifugal compressor, the non-uniform degree of the airflow at the outlet of the centrifugal impeller is improved, the airflow speed is also improved, the Mach number at the inlet of the radial diffuser reaches high subsonic or even ultrasonic, shock waves are formed at the inlet or the passage of the diffuser, and the performance of the centrifugal compressor is influenced. Meanwhile, in order to reduce the windward area of the engine and improve the thrust-weight ratio of the engine, the radial size of the engine needs to be reduced to the maximum extent, along with the reduction of the outer diameter of the engine, the length of a radial diffuser of the centrifugal compressor is reduced, the diffusion load of the diffuser is increased rapidly, so that the flow channel separation in a blade passage is easy to occur, the loss in the diffuser is increased, and the design of the diffuser is more difficult.
In the prior art, a radial diffuser and an axial diffuser are made into an integral structure (such as CN201410453415.4, CN200810196137.3 and the like), so that the mixing loss of a turning section between the radial diffuser and the axial diffuser is reduced, the maximum outer diameter of the diffuser is favorably reduced on the premise that the characteristics of a compressor are not changed, but the integral diffuser blades can deflect from a pressure surface to a suction surface simultaneously in the process of turning from the radial direction to the axial direction, and when the radial height of the diffuser is small, the diffuser blades are seriously twisted, so that the design, the modeling and the processing of the diffuser blades are difficult.
Disclosure of Invention
In view of the above disadvantages and shortcomings of the prior art, the present invention aims to provide a diffuser structure of a centrifugal compressor with blades fused with a casing and a hub, wherein the diffuser blades are fused with the casing and the hub of a diffuser flow passage to complete the modeling of the diffuser blades, so that the maximum outer diameter of the diffuser is ensured to be reduced under the condition that the diameter of the diffuser inlet is not changed, and the distortion degree of the diffuser blades under a smaller radial to axial turning radius can be effectively reduced.
The technical scheme adopted by the invention for realizing the technical purpose is as follows:
a centrifugal compressor diffuser structure with blades fused with a casing and a hub comprises a diffuser disc and a plurality of diffuser blades which are integrally formed at the circumferential edge part of the diffuser disc and are uniformly distributed, a space between every two adjacent diffuser blades forms a diffuser airflow channel, each diffuser blade comprises a radial blade segment formed on the end surface of the diffuser disc and an axial blade segment formed on the edge of the diffuser disc, each diffuser airflow channel comprises a radial diffuser airflow channel segment and an axial diffuser airflow channel segment, and the centrifugal compressor diffuser structure is characterized in that,
the diffuser vane comprises a diffuser leading edge formed at the leading end of the radial vane segment and a diffuser trailing edge formed at the trailing end of the axial vane segment,
the vane pressure surface of the radial vane segment gradually transitions from the diffuser leading edge to the hub of the axial diffuser flow passage segment downstream of the diffuser flow passage,
the vane suction surface of the radial vane segment gradually transitions from the diffuser leading edge downstream of the diffuser flow path to a portion of the casing of the axial diffuser flow path segment,
the hub located at the radial diffuser airflow passage section develops downstream along the diffuser airflow passage and gradually changes into the blade suction surface of the axial blade section,
the casing positioned at the radial diffuser airflow passage section develops downstream along the diffuser airflow passage, and the casing at the axial diffuser airflow passage section and the casing part converted from the blade suction surface of the radial blade section jointly form the casing at the axial diffuser airflow passage section,
and regenerating a curved surface from the intersection of the casing of the radial diffuser airflow passage section and the blade pressure surface of the radial blade section, wherein the curved surface develops downstream along the diffuser airflow passage and gradually increases from zero in width to form the pressure surface of the axial blade section.
Further, the blade pressure surface and the blade suction surface of the radial blade section intersect at the diffuser leading edge to form a sharp-edge diffuser leading edge to adapt to high Mach number incoming flow.
Further, the regenerated curved surface has zero width at the intersection of the blade pressure surface of the radial blade section and the casing of the radial diffuser airflow passage section, and is continuously twisted along with the downstream development of the regenerated curved surface, and the regenerated curved surface gradually increases in width to form the pressure surface of the axial blade section.
Further, the cross section of the throat part at the airflow passage section of the radial diffuser is quadrilateral.
Further, the cross-sectional shapes of the radial diffuser airflow passage section and the axial diffuser airflow passage section are pentagons.
Further, the diffuser blade count is between 10 and 35.
Further, the ratio of the maximum outer diameter of the diffuser to the inlet diameter of the diffuser is preferably selected to be less than 1.3.
Compared with the existing blade diffuser, the diffuser structure of the centrifugal compressor with the blades fused with the casing and the hub has the obvious technical effects that: (1) the diffuser blades connect the radial diffuser blades and the axial diffuser blades into a whole, so that the mixing loss in a diffuser channel is reduced, and the outer diameter of the diffuser can be further reduced on the premise that the total loss of the compressor is not changed; (2) the sharp front edge formed by the blade pressure surface and the blade suction surface of the radial blade section at the front edge of the diffuser can better adapt to high Mach number incoming flow; (3) through the structure that the diffuser blades are fused with the casing and the hub, the maximum outer diameter of the diffuser is reduced under the condition that the diameter of the diffuser inlet is unchanged, meanwhile, the distortion degree of the diffuser blades under the smaller radial to axial turning radius can be effectively reduced, the blades are easy to design and process, the diffuser blades can be directly applied to the centrifugal compressor of the small and medium-sized aero-engine, the outer diameter of the engine can be reduced on the premise that the processing cost is not increased and the performance of the compressor is not reduced, and the thrust-weight ratio of the engine is improved.
Drawings
FIG. 1 is a front view of a centrifugal compressor diffuser of the present invention with blades fused to a casing and hub;
FIG. 2 is a rear view of the diffuser structure of the present invention;
FIG. 3 is a three-dimensional view of the diffuser structure of the present invention;
FIG. 4 is another three-dimensional view of a diffuser structure of the present invention;
FIG. 5 is a meridional view of a diffuser structure of the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples, which are illustrative of the present invention and are not to be construed as being limited thereto.
As shown in fig. 1 to 5, the diffuser structure of the centrifugal compressor with the blades fused with the casing and the hub comprises a diffuser body 1, wherein the diffuser body 1 consists of diffuser blades and a diffuser disc, the number of the diffuser blades is between 10 and 35, and the diffuser blades can be machined by milling diffuser airflow channels 9 on the diffuser disc during machining. The diffuser blade structure comprises a diffuser disc, a plurality of diffuser blades and diffuser airflow channels, wherein the diffuser blades are integrally formed and evenly distributed on the circumferential edge part of the diffuser disc, the space between every two adjacent diffuser blades forms a diffuser airflow channel 9, each diffuser blade comprises a radial blade segment formed on the end surface of the diffuser disc and an axial blade segment formed on the edge of the diffuser disc, each diffuser airflow channel 9 comprises a radial diffuser airflow channel segment and an axial diffuser airflow channel segment, and the diffuser blade channels 9 are directly rotated to the axial direction from the radial direction. The diffuser vane includes a diffuser leading edge 5 formed at the leading end of the radial vane segment and a diffuser trailing edge 8 formed at the trailing end of the axial vane segment. The pressure surface 6 of the blade near the leading edge 5 of the diffuser intersects the suction surface 2 of the blade near the leading edge 5 of the diffuser to form a sharp edge 5, i.e., the leading edge 5 of the diffuser blade.
The integrated blade of the diffuser is formed by fusing a pressure surface, a suction surface, a casing and a hub. The pressure surface 6 of the blade near the diffuser leading edge no longer acts as a pressure surface of the blade in the process of progressing downstream of the diffuser passage, but gradually transitions to the hub of the diffuser passage. The suction surface 2 of the vane near the leading edge of the diffuser also no longer acts as a suction surface for the vane as it progresses downstream in the diffuser passage, but rather gradually decreases in width and becomes part of the diffuser casing. The width of the curved surface 7 at the intersection of the pressure surface of the front edge of the diffuser and the casing is zero, and the width of the curved surface 7 gradually increases as the curved surface develops downstream to form a pressure surface at the rear half part of the passage of the diffuser. The hub 3 at the inlet of the diffuser passage develops downstream along the diffuser passage and no longer acts as a hub for the diffuser passage, gradually changing into the suction surface of the diffuser blades. The casing at the diffuser inlet develops backwards along the diffuser passage, and the casing at the diffuser rear half section and part of the casing surface 2 converted from the suction surface of the diffuser front edge jointly form the casing of the diffuser passage. The diffuser blade is finally formed by six curved surfaces, namely a curved surface 6 fusing a pressure surface and a hub of the diffuser, a curved surface 2 fusing a suction surface and a casing of the diffuser, a curved surface 3 fusing the hub and the suction surface of the diffuser, a curved surface 7 forming a pressure surface of the rear half part of the diffuser, a blade top curved surface 4 of the diffuser blade and a tail edge plane 8 of the diffuser blade, so that the modeling of the diffuser blade is completed. The cross section of the diffuser airflow passage 9 is quadrilateral except for the cross section of the throat part, and the cross section of the rest part is pentagonal.
Because diffuser air flow passage 9 can be directly changeed the air current from radial to axial, reduce the mixing loss between radial diffuser and the axial diffuser, consequently compare with the diffusion system of traditional radial diffuser with axial diffuser, this kind of diffuser can further reduce the diffuser external diameter, makes the diffuser load increase, can also reach the performance the same with traditional diffuser simultaneously. The front edge 5 of the diffuser is a sharp edge and can better adapt to incoming flow with high Mach number. Due to the fact that the maximum outer diameter is reduced, the ratio of the radius of the blade top 10 at the tail edge of the diffuser to the radius of the leading edge 5 at the inlet of the diffuser is reduced, the turning radius of a passage of the diffuser is reduced, meanwhile, the diffuser blade deflects from the pressure surface to the suction surface, and therefore the twisting degree of the diffuser blade is increased. The diffuser blade greatly reduces the distortion degree of the diffuser blade and reduces the design and processing difficulty by dividing the pressure surface into the upstream curved surface 6 and the downstream curved surface 7 and dividing the suction surface into the upstream curved surface 2 and the downstream curved surface 3.
In addition, it should be noted that, in the present specification, only the case where the pressure surface and the suction surface of the diffuser blade are divided into two sections, i.e., the upstream section and the downstream section, and are fused with the casing and the hub is described, the case is also applicable to a multi-section blade molding type where the pressure surface and the suction surface of the diffuser blade are divided from the upstream section to the downstream section, and the shapes, the names, and the like of the blades may be different. All equivalent or simple changes of the structure, the characteristics and the principle of the invention which are described in the patent conception of the invention are included in the protection scope of the patent of the invention. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.

Claims (7)

1. A centrifugal compressor diffuser structure with blades fused with a casing and a hub is characterized by comprising a diffuser disc and a plurality of diffuser blades which are integrally formed at the circumferential edge part of the diffuser disc and are uniformly distributed, a space between every two adjacent diffuser blades is formed into a diffuser airflow channel, each diffuser blade comprises a radial blade segment formed on the end surface of the diffuser disc and an axial blade segment formed on the edge of the diffuser disc, each diffuser airflow channel comprises a radial diffuser airflow channel segment and an axial diffuser airflow channel segment, and airflow is directly converted from the radial direction to the axial direction, so that the mixing loss between the radial diffuser and the axial diffuser is reduced;
the diffuser vane comprises a diffuser leading edge formed at the leading end of the radial vane segment and a diffuser trailing edge formed at the trailing end of the axial vane segment,
the vane pressure surface of the radial vane segment gradually transitions from the diffuser leading edge to the hub of the axial diffuser flow passage segment downstream of the diffuser flow passage,
the vane suction surface of the radial vane segment gradually transitions from the diffuser leading edge downstream of the diffuser flow path to a portion of the casing of the axial diffuser flow path segment,
the hub located at the radial diffuser airflow passage section develops downstream along the diffuser airflow passage and gradually changes into the blade suction surface of the axial blade section,
the casing positioned at the radial diffuser airflow passage section develops downstream along the diffuser airflow passage, and the casing at the axial diffuser airflow passage section and the casing part converted from the blade suction surface of the radial blade section jointly form the casing at the axial diffuser airflow passage section,
and regenerating a curved surface from the intersection of the casing of the radial diffuser airflow passage section and the blade pressure surface of the radial blade section, wherein the curved surface develops downstream along the diffuser airflow passage and gradually increases from zero in width to form the pressure surface of the axial blade section.
2. The centrifugal compressor diffuser structure of claim 1 wherein the vane pressure and suction surfaces of the radial vane segment intersect at the diffuser leading edge to form a sharp edge diffuser leading edge to accommodate high mach number incoming flows.
3. The centrifugal compressor diffuser structure of claim 1 wherein the regenerated curved surface has a width of zero at the intersection of the vane pressure surface of the radial vane segment and the casing of the radial diffuser flow passage segment, and is twisted and increased in width as it progresses downstream to form the pressure surface of the axial vane segment.
4. The centrifugal compressor diffuser structure of claim 1 wherein a cross-sectional shape of a throat at the radial diffuser flow passage section is quadrilateral.
5. The centrifugal compressor diffuser structure of claim 1 wherein the radial diffuser flow passage section and the axial diffuser flow passage section are pentagonal in cross-sectional shape.
6. The centrifugal compressor diffuser structure of claim 1 wherein the number of diffuser blades is between 10 and 35.
7. The centrifugal compressor diffuser structure of claim 1 wherein the ratio of the diffuser maximum outer diameter to the diffuser inlet diameter is selected to be less than 1.3.
CN201810128459.8A 2018-02-08 2018-02-08 Centrifugal compressor diffuser structure with blades, casing and hub fused Active CN108386389B (en)

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CN110005525A (en) * 2019-03-01 2019-07-12 南京航空航天大学 It is a kind of to go the compressor of whirl spraying mouth to subtract vortex structure with cascade-type
CN112377268A (en) * 2020-11-13 2021-02-19 中国航发湖南动力机械研究所 Integrated diffuser for additive manufacturing

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CN101363452A (en) * 2008-09-16 2009-02-11 南京航空航天大学 Conformality passage type diffuser and three-dimensional design method thereof
CN201281045Y (en) * 2008-09-16 2009-07-29 南京航空航天大学 Conformal passage type diffuser
ITCO20120055A1 (en) * 2012-11-06 2014-05-07 Nuovo Pignone Srl RETURN CHANNEL SHOVEL FOR CENTRIFUGAL COMPRESSORS
CN103775388B (en) * 2014-01-08 2015-12-09 南京航空航天大学 Plunder and turn round formula three dimendional blade Diffuser and design method
CN104343734B (en) * 2014-09-05 2018-06-19 北京动力机械研究所 Centrifugal compressor

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