CN106089807A - A kind of diffuser based on fractal blade - Google Patents

Abstract

The invention provides a diffuser based on fractal blades, which includes an upper cover plate, a lower cover plate and a fractal blade group, the fractal blade group is sandwiched between the upper cover plate and the lower cover plate, the upper cover plate, the lower cover plate An air flow channel is formed between the fractal vane group, and the pressure increases after the air flow passes through the gas channel; the multi-stage fractal vane of the present invention can inhibit flow separation, reduce flow blockage and flow loss, and increase the diffusion capacity and efficiency of the diffuser , which is conducive to improving the efficiency of the whole machine, reducing the size of the whole machine, and improving the thrust-to-weight ratio/power-to-weight ratio; it is easy to process and low in production cost; it can be directly installed on the diffuser section of the centrifugal compressor, which is convenient for the transformation and upgrading of the compressor.

Description

A Diffuser Based on Fractal Vanes

technical field

The invention relates to the technical field of gas compression devices, in particular to a diffuser based on fractal blades, which is especially suitable for various devices with centrifugal gas compressors, such as aviation gas turbines, power generation gas turbines, and air-conditioning compressors.

Background technique

The centrifugal compressor is an important component in most small gas turbines and turboshaft engines, consisting of an impeller and a diffuser. The role of the diffuser is not only to convert the kinetic energy of the centrifugal impeller rotation into the airflow energy into pressure potential energy, but also to twist the high-speed airflow with radial and tangential velocities flowing out of the centrifugal impeller into pure axial airflow as much as possible through the blades. supplied to the combustion chamber for combustion. The performance of the diffuser directly affects the working state of the compressor stage and the combustion chamber, which in turn has a greater impact on the performance of the whole machine, and the flow loss generated by the diffuser accounts for about 30% of the loss of the centrifugal compressor stage. Efficiency, pressure ratio and stable operating range have a significant impact.

Diffusers for centrifugal compressors can generally be divided into vaneless diffusers, vaned diffusers and tubular diffusers. The diffusers that are widely used in aero-engines today are mainly vane diffusers and tube diffusers. The vaneless diffuser has a simple structure and a wide working range, but the airflow basically flows along an equiangular helix, the process is long and the loss is large. It is often used in centrifugal compressors with small pressure ratio, low efficiency requirements, small radial size restrictions, and large impeller outlet airflow angle (relative to tangential). The tubular diffuser is composed of a series of diffuser pipes uniformly distributed along the circumferential direction. The two adjacent tubular diffuser passages are intersected at the inlet part, and before the dovetail is formed on the diffuser inlet disc and the wheel cover side Compared with the traditional vane diffuser, the dovetail leading edge of the tubular diffuser is more adaptable to the flow of high Mach number, which can effectively improve the efficiency of high-pressure ratio centrifugal and stable working margin, which is very suitable for high-pressure than centrifugal compressors. However, the tubular diffuser has problems such as difficulty in processing, high cost, and difficulty in guaranteeing processing accuracy.

The vane diffuser can not only slow down the diffusion by increasing the radius, but also deflect the airflow at a certain angle, so that the flow area can be further increased to improve the diffusion capacity, and its efficiency is relatively high. Compared with the vaneless diffuser, the vane diffuser with the same size has stronger diffusion capacity and higher efficiency. Moreover, the vane diffuser can effectively control the outlet flow angle of the diffuser, which provides a good flow environment for the downstream combustion chamber or recirculator. The disadvantage of the existing vaned diffuser is that due to the existence of vanes, the throat of the vaned diffuser is prone to blockage, and the impact loss of the vaned diffuser is large under variable working conditions, and the efficiency drops significantly, especially in In the case of a large angle of attack, severe separation is likely to occur in the flow channel, and even lead to surge. However, in the case of small flow, the flow in the vane diffuser often deteriorates first, which causes the surge of the whole machine. Therefore, there is an urgent need in the art for a diffuser that can balance the aerodynamic performance and processing cost of the diffuser.

Contents of the invention

(1) Technical problems to be solved

In order to solve the above-mentioned problems in the prior art, the present invention provides a diffuser based on fractal blades.

(2) Technical solution

The present invention provides a diffuser based on fractal blades, including: an upper cover plate 1, a lower cover plate 2 and a fractal blade group; the fractal blade group is sandwiched between the upper cover plate 1 and the lower cover plate 2 Between the upper cover plate 1, the lower cover plate 2 and the fractal vane group, an air flow passage 9 is formed, and the pressure of the air flow increases after passing through the air passage 9.

Preferably, the set of fractal blades includes N stages of fractal blades radially distributed along the diffuser, wherein the next-stage fractal blades are located in the direction of increasing radius of the previous-stage fractal blades, and the next-stage fractal blades The number of fractal blades is twice the number of upper-level fractal blades, each blade of the upper-level fractal blade corresponds to two blades of the lower-level fractal blade, and the two blades of the lower-level fractal blade are symmetrically arranged on the upper level Fractal leaf blade sides.

Preferably, the diffuser is divided into a plurality of fan-shaped diffuser sections along the circumference, the number of the diffuser sections is the same as the number of first-stage fractal blades, and for each diffuser section, its n-th fractal The blade number of the blade is 2 ^n-1 .

Preferably, the blades of the N-level fractal blades are straight blades or curved blades.

Preferably, along the increasing direction of the radius of the diffuser, the blade lengths of the N stages of fractal blades are the same; or increase step by step; or decrease step by step.

Preferably, along the increasing direction of the diffuser radius, the vane heights of the N stages of fractal vanes are the same; or increase step by step; or decrease step by step.

Preferably, the blades of the N-level fractal blades have uniform thickness; or, have a streamlined shape with uneven thickness.

Preferably, the blade inlet end of the first stage fractal blade is dovetail-shaped, zigzag-shaped, arc-shaped or multi-arc-shaped.

Preferably, the upper cover plate 1 and the lower cover plate 2 are annular plate-shaped structures, a gas inlet 3 is formed between the inner edge of the upper cover plate and the inner edge of the lower cover plate, and the outer edge of the upper cover plate A gas outlet 4 is formed between the outer edge of the lower cover plate, the first fractal blade is located at the gas inlet, and the Nth fractal blade is located at the gas outlet.

Preferably, the diffuser further includes: a turning and rectifying channel, the turning and rectifying channel is a cylindrical structure surrounding the diffuser, and its gas inlet is radially opposite to the gas outlet 4 of the diffuser, so The turning and rectifying channel is turned by 90 degrees, and its gas outlet extends along the axial direction.

(3) Beneficial effects

As can be seen from the above technical solutions, the diffuser based on fractal blades of the present invention has the following beneficial effects:

(1) According to the fractal theory, multi-stage fractal blades are arranged in the diffuser along the direction of increasing radius, which can effectively inhibit flow separation, reduce flow blockage and flow loss, and increase the diffusion capacity and efficiency of the diffuser, which is beneficial to Improve the efficiency of the whole machine, reduce the size of the whole machine, and increase the thrust-to-weight ratio/power-to-weight ratio;

(2) The number of increasing blades in the radial direction gradually increases according to the law of 2 ^n-1 , and the next-level fractal blades are symmetrically arranged on both sides of the upper-level fractal blades, which is conducive to further increasing the diffusion capacity of the diffuser , Inhibit flow separation and reduce flow loss, further improving the diffusion efficiency of the diffuser;

(3) The fractal blades can be straight blades, which are easy to process and low in production cost; they can also be curved blades to ensure the required air inlet angle and air outlet angle;

(4) The fractal blade can have a uniform thickness, which is convenient for processing and manufacturing; it can also be a streamlined shape with uneven thickness, which can further reduce the flow loss;

(5) On the basis of not changing the structure of the original centrifugal compressor, the diffuser of the present invention can be directly installed on the diffuser section of the centrifugal compressor, so as to facilitate the transformation and upgrading of the compressor;

(6) The inlet end of the first-stage fractal blade can be shaped like a dovetail, which can further enhance the diffusion effect of the diffuser;

(7) The diffuser may also include a turning rectification channel and a rectification partition to guide the flow direction of the gas and further improve the efficiency of the compressor.

Description of drawings

Fig. 1 is the structural representation of the diffuser based on fractal vane of the embodiment of the present invention;

Fig. 2 is the top view of a diffuser section of the diffuser shown in Fig. 1 omitting the upper cover plate and the lower cover plate;

Fig. 3 is a three-dimensional view of a diffuser section of the diffuser shown in Fig. 1 with an upper cover plate and a lower cover plate;

Fig. 4 is a schematic diagram of a dovetail-shaped inlet end of the first-stage fractal blade.

【Symbol Description】

1-upper cover; 2-lower cover; 3-gas inlet;

4-gas outlet; 5-first fractal blade; 6-second fractal blade;

7-the third-level fractal blade; 8-the fourth-level fractal blade; 9-airflow channel;

10 - The inlet end of the first stage fractal blade.

detailed description

The invention provides a diffuser based on fractal blades. Fractal is a general term for self-similar graphics and structures, and is a universal law contained in nature. The invention uses fractal theory to design the distribution mode and number of fractal blades in the diffuser. , can effectively improve the diffusion capacity of the diffuser, broaden the stable working range of the diffuser, prevent flow separation, and reduce the mixing loss at the outlet of the diffuser. The diffuser of the present invention has large flow area, small flow blockage, and small flow loss, which is beneficial to improve the efficiency of the whole machine, reduce the size of the whole machine, and improve the thrust-to-weight ratio/power-to-weight ratio without changing the structure of the original centrifugal compressor. On the basis of direct replacement of the diffuser section of the original centrifugal compressor, it is convenient to realize the transformation and upgrading of the device.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

As shown in Figures 1-4, the diffuser based on fractal blades according to the embodiment of the present invention includes an upper cover plate 1, a lower cover plate 2 and a fractal blade group, and the upper cover plate 1 and the lower cover plate 2 are annular plates The gas inlet 3 is formed between the inner edge of the upper cover plate and the inner edge of the lower cover plate, the gas outlet 4 is formed between the outer edge of the upper cover plate and the outer edge of the lower cover plate, and the fractal blade group is sandwiched between the upper cover Between the plate 1 and the lower cover plate 2, between the upper cover plate 1 and the lower cover plate 2 and the fractal vane group, an airflow passage 9 is formed, and the airflow passage 9 is expanded along the direction of increasing the diffuser radius, and can also remain unchanged , the gas flow enters the diffuser from the gas inlet 3, and after passing through the gas channel 9, the pressure increases and flows out from the gas outlet 4.

As shown in the figure, the fractal vane set of this embodiment includes four fractal vanes radially distributed along the diffuser: the first fractal vane 5, the second fractal vane 6, the third fractal vane 7 and the fourth fractal vane Fractal blades 8, the first stage fractal blades 5 are located at the gas inlet 3, the fourth stage fractal blades 8 are located at the gas outlet 4, and the next stage fractal blades are located at the direction of increase of the diffuser radius of the previous stage fractal blades (i.e. From the gas inlet 3 to the gas outlet 4 or the downstream direction), each fractal blade is arranged in the circumferential direction and is ring-shaped as a whole. Each blade of the blade corresponds to two blades of the next-level fractal blade, and the two blades of the lower-level fractal blade are symmetrically arranged on both sides of the blade of the upper-level fractal blade.

The diffuser can be divided into multiple fan-shaped diffuser sections along the circumference, and the number of diffuser sections is the same as the number of first-stage fractal blades. For each diffuser section, it includes one first-stage fractal blade 5, 2 pieces of second-level fractal blades 6, 4 pieces of third-level fractal blades 7 and 8 pieces of fourth-level fractal blades 8, that is, for each diffuser section, the number of n-level fractal blades is 2 ^{n- 1} .

In the diffuser based on fractal blades in the embodiment of the present invention, multi-stage fractal blades are designed in the diffuser along the radius increasing direction according to the fractal theory, which can suppress flow separation, reduce flow blockage and flow loss, and increase the diffuser Diffusion capacity and efficiency. Specifically, for a diffuser with radial flow, as the radius increases, the flow area also gradually increases, that is to say, the degree of gas diffusion increases gradually with the increase of the radius. In this case, if no measures are taken and the number and thickness of the vanes are kept constant, flow separation will occur, increasing flow loss and reducing the diffusion capacity, and the ingenuity of the diffuser based on fractal vanes of the present invention is that, According to the fractal law, on the one hand, the number of blades gradually increases with the increase of the radius direction according to the distribution law of 2 ^n-1 ; on the other hand, the blades of the next level of fractal are symmetrically arranged These two distribution forms are beneficial to increase the diffusion capacity of the diffuser, inhibit flow separation and reduce flow loss, and improve the diffusion efficiency of the diffuser.

In this embodiment, the fractal blades can be straight blades, which are easy to process and low in production cost; they can also be curved blades, which match the inlet angle and outlet angle at the same time, so as to ensure the required inlet angle and outlet angle . The lengths of the fractal blades at each stage can be the same or different, preferably along the direction of increasing the radius of the diffuser, the length of the fractal blades increases step by step. The heights of the fractal blades at all levels can be the same or different, preferably the heights of the fractal blades at all levels are the same. For each piece of fractal blade, it can have a uniform thickness, which can facilitate processing, and can also have a streamlined shape with uneven thickness, which can further reduce flow loss.

Preferably, as shown in FIG. 4 , the inlet end 10 of the first-stage fractal blade can be modified, and the inlet end can be dovetail-shaped, which can further enhance the diffusion effect of the diffuser. Further, the inlet port can also be in the shape of zigzag, arc, or multiple arcs.

When the diffuser of this embodiment is working, the gas flowing out of the impeller enters the gas flow channel from the gas inlet, and flows out of the diffuser through the gas outlet, and the gas flow channel of the diffuser guides the direction of gas flow, so as to realize the deceleration and expansion of the gas. On the basis of not changing the structure of the original centrifugal compressor, it is directly installed on the diffuser section of the centrifugal compressor, which facilitates the transformation and upgrading of the compressor.

In other embodiments of the present invention, the diffuser also includes a turning and rectifying channel, which is a cylindrical structure surrounding the diffuser, and its gas inlet is radially opposite to the gas outlet 4 of the diffuser , turning the rectification channel by 90 degrees, and its gas outlet is along the axial direction, turning the gas flow to the gas inlet direction of the next-stage diffuser or combustion chamber. Furthermore, a rectification partition is arranged in the turning rectification channel, and the rectification partition can guide the flow direction of the gas to further improve the efficiency of the compressor.

It can be understood that although the diffuser in this embodiment includes four-stage fractal blades, this is only an exemplary description, and the present invention is not limited thereto. Based on factors such as the size of the diffuser and the diffusion effect, the diffuser The fractal blade group can have N levels of fractal blades, 1≤N≤100, wherein the number of first-level fractal blades can be 3-100 pieces, which will not affect the realization of the technical effect of the present invention and fall within the protection scope of the present invention.

So far, the present embodiment has been described in detail with reference to the drawings. Based on the above description, those skilled in the art should have a clear understanding of the diffuser based on fractal blades of the present invention.

It should be noted that, in the accompanying drawings or in the text of the specification, implementations that are not shown or described are forms known to those of ordinary skill in the art, and are not described in detail. In addition, the above definition of each element is not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily modify or replace them, for example:

(1) Fractal blades can also choose other structures;

(2) The directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only referring to the directions of the drawings, and are not used to limit The protection scope of the present invention;

(3) The above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, technical features in different embodiments can be freely combined to form more embodiments.

In summary, the diffuser based on fractal blades of the present invention can be used in compressors for aviation, power generation, chemical industry, metallurgy, and HVAC. Simple and compact diffuser that is easy to process and manufacture.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a diffuser based on fractal blade, it is characterised in that including: upper cover plate (1), lower cover (2) and fractal blade Group；Described fractal vane group is located between described upper cover plate (1) and lower cover (2), described upper cover plate (1), lower cover (2) with Forming gas channel (9) between fractal vane group, air-flow pressure after described gas passage (9) increases.

2. diffuser as claimed in claim 1, it is characterised in that described fractal vane group includes along diffuser radially-arranged The fractal blade of N level, wherein, the fractal blade of next stage be positioned at the fractal blade of upper level along diffuser radius augment direction, next The twice that quantity is the fractal blade quantity of upper level of the fractal blade of level, each blade correspondence next stage of the fractal blade of upper level Two blades of fractal blade, the said two blade of the fractal blade of next stage is symmetricly set on the blade of the fractal blade of upper level Both sides.

3. diffuser as claimed in claim 2, it is characterised in that described diffuser is circumferentially divided into the diffusion of multiple sector Section, the quantity of the quantity of described diffuser blade fractal with the first order is identical, for each diffuser, its n-th grade of fractal leaf The blade quantity of sheet is 2^n-1。

4. diffuser as claimed in claim 2, it is characterised in that the blade of the described fractal blade of N level is prismatic blade or bending Blade.

5. diffuser as claimed in claim 2, it is characterised in that along diffuser radius augment direction, the described fractal blade of N level Length of blade identical；Or increase step by step；Or reduce step by step.

6. diffuser as claimed in claim 2, it is characterised in that along diffuser radius augment direction, the described fractal blade of N level Blade height identical；Or increase step by step；Or reduce step by step.

7. diffuser as claimed in claim 2, it is characterised in that the blade of the described fractal blade of N level has homogeneous thickness； Or, there is the streamline-shaped of uneven thickness.

8. diffuser as claimed in claim 2, it is characterised in that the vane inlet end of the fractal blade of the first order be swallow-tail form, Zigzag, circular arc or many circular arc.

9. diffuser as claimed in claim 2, it is characterised in that described upper cover plate (1) and lower cover (2) are annular plate-like knot Structure, forms gas feed (3), the outer rim of described upper cover plate and lower cover between inner edge and the inner edge of lower cover of described upper cover plate Outer rim between formed gas outlet (4), the fractal blade of the first order is positioned at gas feed, and the fractal blade of N level is positioned at gas Exit.

10. diffuser as claimed in claim 9, it is characterised in that described diffuser also includes: rectification passage of turning back, described Rectification passage of turning back is the cylinder-like structure around diffuser, its gas feed the most just gas outlet (4) to diffuser, Described rectification passage of turning back turns to through 90 degree, and its gas outlet axially extends.