CN113586560A

CN113586560A - Pit type intermediate casing capable of inhibiting flow separation

Info

Publication number: CN113586560A
Application number: CN202110852831.1A
Authority: CN
Inventors: 辛建池; 王龙; 刘向阳
Original assignee: Dalian Maritime University
Current assignee: Dalian Maritime University
Priority date: 2021-07-27
Filing date: 2021-07-27
Publication date: 2021-11-02
Anticipated expiration: 2041-07-27
Also published as: CN113586560B

Abstract

The invention discloses a pit type intermediary case for inhibiting flow separation, which comprises an intermediary case outer ring, an intermediary case inner ring and a plurality of support plates, wherein the intermediary case outer ring is provided with a plurality of support plates; the intermediate casing inner ring is arranged in the intermediate casing outer ring, a flow annular channel is formed between the intermediate casing inner ring and the intermediate casing outer ring, a plurality of support plates are uniformly distributed in the flow annular channel in the circumferential direction, one end of each support plate is connected with the outer wall of the intermediate casing inner ring, the other end of each support plate is connected with the inner wall of the intermediate casing outer ring, and pits used for generating vortex when fluid flows are further formed in the back arc positions of the flow annular channel and/or the support plates. The intermediate casing disclosed by the invention is provided with the pits, so that the mixing of low-energy high-entropy fluid in the boundary layer and fluid outside the boundary layer can be promoted, the kinetic energy level of the boundary layer is further improved, the flow separation is inhibited, the flow loss is reduced, the flow condition in the intermediate casing is further improved, and the pneumatic performance of the intermediate casing is improved.

Description

Pit type intermediate casing capable of inhibiting flow separation

Technical Field

The invention relates to the technical field of fluid machinery, in particular to a pit type intermediate casing for inhibiting flow separation.

Background

In the modern society, fluid machinery increasingly plays an important role in the field of national defense science and technology, and is an important part in the fields of aviation, aerospace, navigation, energy, chemical engineering and the like. The main parts of the fluid machine are connected through a transition section (intermediate casing) to guide airflow from an upstream element to a downstream element, so that the continuity of a flow field between the elements is ensured, and support plates are uniformly distributed in the flow annular channel of the transition section in the circumferential direction and can play a role in supporting. However, the transition section has large radial offset and the support plate causes internal flow disorder, airflow flow separation, flow field deterioration and influences aerodynamic performance, which provides challenges for the structural design of the transition section. The reasonable control of the flow separation in the transition section can reduce the flow loss of the fluid machine to a great extent, reduce the dynamic and static interference, improve the mechanical efficiency and prolong the service life of the fluid machine. Has important significance for relieving energy crisis and implementing sustainable development strategy.

Existing methods of controlling flow separation are largely classified into active flow control techniques and passive flow control techniques. Since active flow control is severely limited by external conditions, the application has certain limitations.

Disclosure of Invention

A pit type intermediary case for inhibiting flow separation comprises an intermediary case outer ring, an intermediary case inner ring and a plurality of support plates;

the intermediate casing inner ring is arranged in the intermediate casing outer ring, a flow annular channel is formed between the intermediate casing inner ring and the intermediate casing outer ring, a plurality of support plates are uniformly distributed in the flow annular channel in the circumferential direction, one end of each support plate is connected with the outer wall of the intermediate casing inner ring, the other end of each support plate is connected with the inner wall of the intermediate casing outer ring, and pits used for generating vortex when fluid flows through are further formed in the back arc part of the flow annular channel and/or the support plates.

Further, the support plate is maximum in thickness along the fluid flowing direction, and one or more rows of the pits are uniformly distributed at the position of the whole height.

Furthermore, the pits are arranged in one or more rows at the back arc of the flow annular channel along the flow direction of the fluid, and the arrangement mode of the pits in two adjacent rows is any one of square arrangement, rhombic arrangement and free arrangement.

Furthermore, the shape of the pit is any one of a spherical pit, a flow direction major axis ellipsoid pit, a span direction major axis ellipsoid pit and a crescent pit.

Furthermore, the depth-diameter ratio of the pits is 1/3-1/4, and the relative depth of the pits is less than 2.78 per thousand.

Compared with the prior art, the pit type intermediate casing for inhibiting flow separation disclosed by the invention has the following beneficial effects: because the back arc of the flow annular channel and/or the support plate are/is also provided with the pits for generating vortex when the fluid flows, the flow vortex generated by the pits can promote the mixing of low-energy high-entropy fluid in the boundary layer and fluid outside the boundary layer, so that the kinetic energy level of the boundary layer is improved, the flow separation is inhibited, the flow loss is reduced, the flow condition in the transition section is improved, and the pneumatic performance of the transition section is improved.

Drawings

FIG. 1 is a block diagram of a dimpled interposer casing for inhibiting flow separation as disclosed herein;

FIG. 2 is a schematic view of an arrangement of dimples;

FIG. 3 is a cross-sectional axial structural view of a dimpled intermediate casing for inhibiting flow separation in accordance with the present disclosure;

FIG. 4 is a cross-sectional shape of the plate;

FIG. 5 is a graph comparing total pressure loss (Cpt) at the outlet of the intermediate case according to the present invention;

FIG. 6 is an analysis of static pressure ratio at the inlet and outlet of the present invention;

FIG. 7 is an analysis of the effect of different relative depth pits on the overall pressure loss coefficient of the intermediate case exit cross-section in accordance with the present invention.

In the figure: 1. the intermediate casing outer ring 2, the intermediate casing inner ring 3, the concave pits on the support plate 4, the concave pits on the back arc 5, the support plate 6 and the flow annular channel.

Detailed Description

Referring to fig. 1, 2 and 3, a concave type intermediate casing for suppressing flow separation according to the present invention comprises an intermediate casing outer ring 1, an intermediate casing inner ring 2 and a plurality of support plates 5;

the intermediate casing inner ring 2 is arranged in the intermediate casing outer ring 1, a flow annular channel 6 is formed between the intermediate casing inner ring 2 and the intermediate casing outer ring 1, a plurality of support plates 5 are uniformly distributed in the flow annular channel 6 in the circumferential direction, one end of each support plate is connected with the outer wall of the intermediate casing inner ring 2, the other end of each support plate is connected with the inner wall of the intermediate casing outer ring 1, and pits for generating vortex when fluid flows are further formed in the back arc position of the flow annular channel 6 and/or the support plates 5.

Specifically, in this embodiment, the flow annular channel 6 and the support plate 5 are provided with dimples for generating a vortex when the fluid flows, as shown in fig. 2 and 3, in this embodiment, the fluid inflow end of the intermediate casing is larger than the fluid outflow end (arrow C in the figure indicates the fluid flow direction), the back arc of the flow annular channel is a transition section (area a in the figure) between the large diameter end and the small diameter end of the outer wall of the inner ring of the intermediate casing, when the fluid inflow end is smaller than the fluid outflow end, the back arc of the flow annular channel is a transition section (area B in the figure) between the small diameter end and the large diameter end of the inner wall of the outer ring of the intermediate casing, the dimples 4 on the back arc are provided at the back arc of the flow annular channel 6, as shown in fig. 4, the cross section of the support plate 5 is an approximately elliptical structure with gradually increasing thickness from both ends to the middle, the support plate is arranged along the flowing direction of the fluid, the pits 3 on the support plate are arranged on two side surfaces of the support plate 5, in the invention, as the pits are arranged at the back arc part of the flowing annular channel and on the support plate and are used as vortex generators, when the fluid at the back arc part and the boundary layer of the support plate flows, vortex structures with different forms are formed in the pits, the generated flowing vortex can promote the mixing of the low-energy high-entropy fluid in the boundary layer and the fluid outside the layer, further improve the kinetic energy level of the boundary layer, inhibit the flow separation, reduce the flow loss, further improve the flowing condition in the transition section and improve the aerodynamic performance of the transition section, and particularly, as shown in figure 5, the change rule of the total pressure loss coefficient (Cpt) of the outlet section of different medium casing structures along with the Mach number is given, so that the total pressure loss coefficient of the casing with the pits arranged on the support plate and the end wall of the medium can be obviously reduced, the maximum can be reduced by 0.007.

Further onThe support plate is provided with one or more rows of pits at the position with the largest thickness along the fluid flowing direction and the whole height, the pits are provided with one or more rows along the fluid flowing direction at the back arc of the flowing annular channel, and the arrangement mode of the pits in two adjacent rows is any one of square arrangement, rhombic arrangement and free arrangement. The shape of the pit is any one of a spherical pit, a flow direction major axis ellipsoid pit, a spanwise major axis ellipsoid pit and a crescent pit; as shown in fig. 6, the inlet/outlet static pressure ratio of the disclosed intermediate casing to the existing intermediate casing can be increased. As shown in FIG. 6, the inlet to outlet section pressure ratio (P) for different intermediary casing structures is given_out/P_in) The mach number is changed. It can be seen that the pressure ratio of the intermediate casing with the recesses arranged simultaneously on the support plate and the end wall is significantly higher, in particular as the mach number increases.

Furthermore, the depth-diameter ratio (the ratio of the depth to the diameter) of the pits is 1/3-1/4, and the relative depth (the ratio of the maximum thickness of the pits to the maximum thickness of the support plate) of the pits is below 2.78 per thousand of the maximum thickness of the support plate. As shown in fig. 7, the influence of the pits with different relative depths on the total pressure loss coefficient of the outlet section of the intermediate casing is shown, and when the relative depth of the pit is 1.39%, the effect of reducing the flow loss of the intermediate casing is best.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A dimpled intermediate casing to inhibit flow separation, comprising: the intermediate casing structure comprises an intermediate casing outer ring, an intermediate casing inner ring and a plurality of support plates;

2. The dimpled intermediary cartridge for inhibiting flow separation according to claim 1, wherein: and one or more rows of the concave pits are uniformly distributed at the position of the support plate with the largest thickness along the fluid flowing direction and the whole height.

3. The dimpled intermediary cartridge for inhibiting flow separation according to claim 1, wherein: the pits are arranged in one row or multiple rows at the back arc of the flow annular channel along the flow direction of the fluid, and the arrangement mode of the pits in two adjacent rows is any one of square arrangement, rhombic arrangement and free arrangement.

4. The dimpled intermediary casing for inhibiting flow separation according to any one of claims 1 to 3, wherein: the pits are in any shape of spherical pits, flow direction major axis ellipsoidal pits, span direction major axis ellipsoidal pits and crescent pits.

5. The dimpled intermediary cartridge for inhibiting flow separation according to claim 4, wherein: the depth-diameter ratio of the pits is 1/3-1/4, and the relative depth of the pits is less than 2.78 per thousand.