CN111550437A - Impeller structure and compressor - Google Patents

Abstract

The invention belongs to the technical field of machinery, and provides an impeller structure and a gas compressor, which comprise: a plurality of blades, wheel hub and wheel back boss, the blade sets up in the wheel hub periphery, wheel back boss is located wheel hub bottom center, just the blade wheel hub with wheel back boss integrated into one piece, the pressure surface, the suction surface of blade and the wheel hub surface forms the runner, wherein wheel hub between the blade is provided with one on the surface and extends to the wheel hub convex surface of runner tail end. The invention can reduce the flow passage area of the fluid on one side of the blade, accelerate the flow speed of the fluid, and is beneficial to improving the kinetic energy of the fluid and resisting the reverse pressure gradient, thereby reducing the generation of wake flow and the mixing loss of an outlet and improving the performance of the compressor.

Description

Impeller structure and compressor

Technical Field

The invention belongs to the technical field of machinery, and particularly relates to an impeller structure and a gas compressor.

Background

In recent years, as emission standards have been upgraded, engine miniaturization has become a trend, and in order to increase the power per liter of the engine, the most effective method is to match the exhaust gas turbocharger. The overall performance of the engine is directly influenced by the advantages and disadvantages of the comprehensive performance of the exhaust gas turbocharger, and the performance of the whole turbocharger can be effectively improved by improving the efficiency of the centrifugal compressor.

At present, besides the performance of a compressor stage is improved by performing fluid dynamics optimization design on a centrifugal compressor impeller blade profile and a volute circumferential flow channel, some passive control measures can be adopted, such as: the performance of the compressor is improved by controlling the clearance of the top of the compressor blade by adopting an abradable coating and improving the surface smoothness of an impeller and a pressure shell. From the flow field distribution of the blade channel of the centrifugal compressor, the flow field near the outlet of the impeller can be composed of two parts of jet flow and wake flow, the fluid speed is higher in the most part of the area near the pressure surface of the blade and the middle of the blade channel, the pressure gradient is larger and larger in the process that the fluid flows from the upstream to the downstream of the blade in the remaining area near the suction surface of the blade, the fluid speed in the area is usually lower, so that the fluid near the outlet of the impeller can not resist the inverse pressure gradient, the countercurrent is finally generated, the width of the wake flow area is called as wake flow area, and the width of the wake flow area can even reach more than half of the width of the outlet of the blade channel, thus, the impeller outlet has great air flow mixing loss, and the performance.

Disclosure of Invention

The invention provides an impeller structure, which can reduce the flow passage area on one side of a blade, is beneficial to improving the fluid kinetic energy, resists the reverse pressure gradient and improves the performance of a gas compressor.

To solve the above problems, the present invention provides an impeller structure, including: a plurality of blades, wheel hub and wheel back boss, the blade sets up in the wheel hub periphery, wheel back boss is located wheel hub bottom center, just the blade wheel hub with wheel back boss integrated into one piece, the pressure surface, the suction surface of blade and the wheel hub surface forms the runner, wherein wheel hub between the blade is provided with one on the surface and extends to the wheel hub convex surface of runner tail end.

Furthermore, the hub convex surface is a convex surface structure with the thickness gradually increasing along the flow direction of the flow channel.

Further, the convex surface of the hub is arranged on one side of the suction surface in the flow passage.

Furthermore, the hub convex surface increases along the direction of the flow direction of the runner, and the position extending the increase of the thickness of the flow direction of the runner is the middle position of the runner and reaches the tail end position of the runner.

Furthermore, the convex surface of the hub is thickened from the direction along the flow direction of the flow channel to the tail end of the flow channel in a convergent shape.

Further, in the circumferential direction of the hub, the hub convex surface is located in an area offset by 50% from the suction surface of the blade.

Further, in the circumferential direction of the hub, the circumferential extension of the hub convex surface occupies 50% of the area of the flow channel.

Furthermore, in the flow direction of the flow channel, the thickening starting position of the convex surface of the hub is 50% -100% of the position of the starting end of the flow channel.

Furthermore, the thickening starting position of the convex surface of the hub is 80% -100% of the position of the starting end of the flow channel.

The invention also provides an air compressor which comprises the impeller structure in any embodiment.

The invention achieves the following beneficial effects: in the embodiment, the hub convex surface extending to the tail end of the flow channel is arranged on the surface of the hub, so that when fluid enters the tail end of the flow channel from the top to the bottom of the flow channel from the flow channel, the formation of the hub convex surface can reduce the flow channel area of the fluid on one side of the blade, accelerate the flow speed of the fluid, be beneficial to improving the kinetic energy of the fluid and resist the reverse pressure gradient, thereby reducing the generation of wake flow and the mixing loss of an outlet and improving the performance of the gas compressor.

Drawings

FIG. 1a is a schematic structural diagram of an impeller structure provided in the present invention;

FIG. 1b is a graph comparing experimental data provided by an embodiment of the present invention;

FIG. 1c is a schematic structural diagram of a relationship curve between mass flow and pressure ratio provided by the present invention;

FIG. 1d is a schematic structural diagram of a relationship curve between mass flow and efficiency provided by the present invention;

FIG. 2 is a schematic cross-sectional structure view of an impeller structure provided by the present invention;

fig. 3 is a schematic structural diagram of a prior art impeller structure.

The device comprises a hub, a blade, a pressure surface, a suction surface, a hub convex surface, a hub shaft hole, a hub back boss and a runner, wherein the blade is 1, the blade is 11, the pressure surface is 12, the suction surface is 2, the hub is 21, the hub convex surface is 22, the.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the prior art, from the flow field distribution of a blade channel of a centrifugal compressor, in the area close to a suction surface of a blade, where the fluid velocity is higher in the area close to the pressure surface of the blade and most of the middle area of the blade channel, the pressure gradient is larger and larger, and the fluid velocity in the area section is usually lower in the process of flowing from the upstream to the downstream of the blade, so that the fluid near the outlet of an impeller cannot resist the adverse pressure gradient, and finally, a reverse flow occurs, the width of a wake flow area sometimes even reaches more than half of the width of the outlet of the blade channel, and the air flow mixing loss at the outlet of the impeller is very large. In the embodiment, because the hub convex surface 21 extending to the tail end of the flow channel 4 is arranged on the bottom surface of the hub 2, when fluid enters the tail end of the flow channel 4 from the top to the bottom of the flow channel 4, the formation of the hub convex surface 4 can reduce the flow channel area of the fluid on one side of the pressure surface of the blade 1, accelerate the flow speed of the fluid, facilitate the improvement of the kinetic energy of the fluid, resist the reverse pressure gradient, thereby reducing the wake flow generation and the outlet mixing loss, and improving the performance of the compressor.

Example one

Fig. 1a is a schematic structural diagram of an impeller structure according to an embodiment of the present invention. An impeller structure comprising: a plurality of blades 1, wheel hub 2 and wheel back boss 3, blade 1 sets up on wheel hub 2 periphery, and wheel back boss 3 is located 2 bottom centers of wheel hub, and blade 1, wheel hub 2 and wheel back boss 3 integrated into one piece, and the pressure face 11, the suction face 12 of blade 1 and wheel hub 2 surface form runner 4, and wherein, be provided with one on the 2 bottom surfaces of wheel hub between blade 1 and extend to the wheel hub convex surface 21 of 4 tail ends of runner.

Wherein, the blade 1 can be provided with a plurality of pieces, and can be arranged in an axial symmetry manner. The blade 1 can be the blade 1 that is "the back bend S type", "the back bend S type" sets up in the periphery of wheel hub 2, and is connected the setting through a long side and wheel hub 2 integrated into one piece. The pressure side 11 of the blade 1 may be referred to as the tangentially upwards side and the suction side 12 may be referred to as the tangentially downwards side. The flow channel 4 is formed between a pressure surface 11 and a suction surface 12 of two adjacent blades 1, the flow channel 4 may be a flow space provided for a fluid, and the aperture of the flow channel 4 may gradually increase from top to bottom. The blades 1 may have a gradually decreasing thickness extending outwards from the connection with the hub 2, which provides a secure connection while ensuring sufficient flow space for the fluid in the flow channel 4. The connecting part between the blade 1 and the hub 2 can be connected in a smooth curved surface manner, so that the smoothness of fluid can be ensured. It should be noted that the present invention may be based on an axisymmetric centrifugal compressor wheel.

The hub 2 may have a truncated cone shape with a small top and a large bottom, and the radius of the portion where the hub is connected to the blade 1 gradually increases from top to bottom, and the radius of the portion where the hub is not connected to the blade 1 is the same. A shaft hole 22 may be provided at the center of the hub 2, and the lower end of the shaft hole 22 penetrates the wheel back boss 3. Shaft hole 22 can be cylindrical structure, and two top interface bores about shaft hole 22 can be greater than shaft hole 22's radius, and shaft hole 22 can be used for passing through interference fit with the motor shaft tip of motor, forms and can dismantle the connection. The motor shaft can be a connecting end between the motor and the impeller, and the motor can drive the impeller to rotate to work.

The wheel back boss 3 can be located at the center of the bottom of the hub 2 and the blade 1 and protrudes downwards, the edge of the wheel back boss 3 extends along the bottom of the hub 2 to the periphery, and when the wheel back boss extends, the wheel back boss 3 presents a curved surface to extend, the gradient from the starting end of the wheel back boss 3 to the position 1/3 is large, and the gradient from the position 1/3 to the position of the tail end is small. Wheel back boss 3 can provide rotation space for blade 1, when external device is connected with wheel back boss 3, can keep safe distance with blade 1, avoids the touching to cause the damage. The blade 1, the hub 2 and the wheel back boss 3 can be integrally formed, and are in seamless connection and strong in integrity.

Referring to fig. 1a, the hub convex surface 21 may be disposed in the flow channel 4 between two adjacent blades 1, and extend to the tail end of the flow channel 4, which may also be referred to as a wake region. The formation of the convex surface 21 of the hub divides the flow channel 4 into two regions with smaller flow channel area, especially the region near the suction surface 12 side of the blade 1, and by reducing the flow channel area of the fluid at the side of the blade 1, the flow speed of the fluid in the wake region can be increased, which is beneficial to improving the kinetic energy of the fluid. L1 in fig. 1a may indicate a location where the hub convex surface 21 is thickened in the lateral direction, and the hub convex surface 21 may be located closer to the left blade 1.

Specifically, as shown in fig. 1b, a comparison graph of experimental data provided by the embodiment of the present invention is shown. The mass flow rate one, the pressure ratio one and the efficiency one are experimental data corresponding to the method provided by the embodiment of the patent scheme. The second mass flow, the second pressure ratio and the second efficiency are experimental data of the prior art scheme. Under the condition of ensuring that the rotating speed of the motor is not changed, a structural diagram of a relation curve between the mass flow and the pressure ratio shown in fig. 1c can be drawn. As can be seen from fig. 1c, the impeller structure provided by the present invention has a larger pressure ratio at a lower mass flow rate, particularly a change before the mass flow rate is 0.09 in the figure, and the larger the mass flow rate, the smaller the corresponding pressure ratio. With continuing reference to FIG. 1, FIG. 1d is a schematic structural diagram of a relationship between mass flow and efficiency provided by the present invention. As can be seen from fig. 1d, the impeller structure provided by the embodiment of the present invention has higher efficiency in the case of low mass flow rate, especially in the case of mass flow rate less than 0.1, compared with the prior art. And as can be seen from fig. 1d, in the relationship diagram, when the mass flow rate is 0.09, there is an efficiency peak 0.763406.

It should be noted that the above-mentioned pressure ratio may refer to a ratio of an outlet pressure to an inlet pressure of the compressor. The above equation for mass flow may be as follows:

mass flow (M) ═ medium density (ρ) × volume flow (Q)

Medium density (ρ) × average flow velocity (v) × flow passage cross-sectional area (a)

The medium may be a fluid flowing through the flow channel 4, the volume flow rate may be a volume of the fluid passing through a cross section of the flow channel 4 in a unit time, which is referred to as "flow rate" and is denoted by Q, the volume flow rate (Q) is an average flow velocity (v) x a flow channel cross-sectional area (a), the average flow velocity may be an average flow velocity of the fluid in the flow channel 4, and the flow channel cross-sectional area may be a cross-sectional area of the fluid flowing through the flow channel 4.

More specifically, in the embodiment of the present invention, by providing a hub convex surface 21 extending to the rear end of the flow channel 4 on the surface of the hub 2, the hub convex surface 4 is formed to reduce the flow channel area (flow channel cross-sectional area) of the fluid on the blade 1 side when the fluid enters the rear end of the flow channel 4 from the top to the bottom of the flow channel 4. As shown in fig. 1b-1d above, a decrease in cross-sectional area of the flow path reduces the mass flow rate, with a smaller mass flow rate corresponding to a larger pressure ratio and a higher efficiency at a portion with a smaller mass flow rate (0.09 or less) relative to a portion with a larger mass flow rate (0.09 or greater), with a maximum efficiency at 0.09.

In the embodiment of the invention, as the hub convex surface 21 extending to the tail end of the flow channel 4 is arranged on the surface of the hub 2, when fluid enters the tail end of the flow channel 4 from the top to the bottom of the flow channel 4, the formation of the hub convex surface 4 can reduce the flow channel area of the fluid on one side of the blade 1, accelerate the flow speed of the fluid, be beneficial to improving the kinetic energy of the fluid and resist the reverse pressure gradient, thereby reducing the generation of wake flow and the mixing loss of an outlet and improving the performance of the gas compressor.

Example two

As shown in fig. 2, fig. 2 is a schematic cross-sectional structure diagram of an impeller structure provided by the present invention. In the first embodiment, the hub convex surface 21 is a convex surface structure in which the thickness gradually increases in the flow direction of the flow passage 4, and the hub convex surface 21 is arranged on the side of the flow passage 4 which is deviated from the suction surface 12.

The flow direction of the flow channel 4 is from top to bottom, i.e., the flow is from the end with the small caliber of the flow channel 4 to the end with the large caliber of the flow channel 4. The thickness of the hub convex surface 21 gradually increases to the end of the flow channel 4 in the flow direction of the flow channel 4. And the convex surface structure of the hub convex surface 21 can be a semi-elliptical structure, namely, a circular arc-shaped curved surface structure. The convex surface 21 of the hub protrudes upwards, and the thickness of the convex surface 21 of the hub gradually increases from top to bottom along the flow direction until the convex surface extends to the tail end of the flow channel 4, and the thickness of the convex surface 21 of the hub reaches the maximum. And one side of the hub convex surface 21 is connected with the suction surface 12, and the other side of the hub convex surface extends to the middle area of the flow channel 4, so that a structure similar to an S shape is integrally formed, the flow channel 4 is divided into two parts, and the flow channel area of the flow channel 4 is reduced.

As shown in fig. 3 provided in connection with the prior art, the flow passage 4 between the suction surface 12 and the pressure surface 11 has only a single flow passage 4, and when the fluid rapidly flows down from the middle portion of the flow passage 4 (the jet flow region of the flow passage 4) between the pressure surface 11 and the flow passage 4, the fluid may impact the wake region, especially the side close to the suction surface 12. The pressure gradient gradually increases in the process of flowing the fluid from top to bottom, and the wake flow area of the flow channel 4 is gentle relative to the jet flow area, so that the flow speed of the fluid is reduced. In the process of flowing the fluid from top to bottom, the lower half part of the suction surface 12, which is close to the suction surface, has a lower diffusion capacity than the lower half part of the pressure surface 11 because of a large flow passage area and a small gradient, so that a sufficient speed needs to be ensured so that the fluid flowing speed can resist the adverse pressure gradient and the occurrence of reverse flow is avoided. The hub convex surface 21 of the present invention may be the side that is disposed in the flow passage 4 and is more biased toward the suction surface 12. The convex surface 21 of the hub is arranged in the flow channel 4 which is more close to the suction surface 12, so that the single flow channel 4 can be divided into two smooth flow channel 4 areas, and the convex part can channel and press the fluid to the two sides of the convex part, thereby ensuring the concentration of the fluid and generating faster flow velocity to resist the adverse pressure gradient.

Furthermore, the thickness of the hub convex surface 21 increases along the flow direction of the flow channel 4, and the position where the thickness increases along the flow direction of the flow channel 4 is the middle position of the flow channel 4 and reaches the tail end position of the flow channel 4; the hub convex surface 21 is thickened from the direction of the flow channel 4 to the tail end of the flow channel 4 in a convergent shape; in the flow direction of the flow channel 4, the thickening starting position of the hub convex surface 21 is 50% -100% of the position of the starting end of the flow channel 4; the thickening starting position of the hub convex surface 21 is 80% -100% of the position of the starting end of the flow passage 4.

Specifically, referring to L2 in fig. 2, L2 is the region of the hub convex surface 21 where the thickness changes. Considering that the flow velocity in the wake area of the flow channel 4 is slow and the reverse flow is likely to occur, the position where the thickness of the hub convex surface 21 gradually increases in the flow direction of the flow channel 4 may be from the middle position of the flow channel 4 to the end position of the flow channel 4, or may indicate that the thickening start position is from the 50% position to the 100% position of the start end of the flow channel 4, and the thickening start position converges, one side of the thickening start position smoothly extends to the suction surface 12, and the other side of the thickening start position extends to the middle position of the flow channel 4, so that the flow channel 4 is divided into two smaller flow channels, and the flow channel area near the suction surface 12 side is smaller, which is more beneficial to increasing the flow velocity of the.

As an alternative embodiment, the thickening start position of the hub convex surface 21 in the flow direction may be set to be 80% -100% of the position of the start end of the flow passage 4, and the thickening position may be used as a preferable region to further facilitate the increase of the flow speed of the fluid.

Further, in the circumferential direction of the hub 2, the hub convex surface 21 is located within 50% of the area biased toward the suction surface 12 of the blade 1; so as to improve the fluid kinetic energy of the partial suction surface area.

As a further improvement, the circumferential extension of the hub convexity 21 in the circumferential direction of the hub 2 occupies 50% of the area of the flow channel 4.

Specifically, in the circumferential direction of the hub 2, the thickness of the hub convex surface 21 may increase in a range from the suction surface 12 side to 50% of the flow passage 4, and specifically, refer to L1 in fig. 1 a. The convex surface 21 of the hub forms an S-shaped structure with the suction surface 12, so that the side of the flow channel 4 close to the suction surface 12 forms a convergent shape with a high middle part and low two ends along the flow direction. And the hub land 21 occupies an area that is 50% of the area in the circumferential direction of the flow channel 4, i.e., occupies half of the flow channel 4 as viewed in the circumferential direction. Because the fluid is more easily diffused in the wake area near the suction surface 12 and the flow rate is low, the hub convex surface 21 is arranged in 50% of the area of the flow channel 4 near the suction surface 12, so that the flow channel area of the fluid near the suction surface 12 can be reduced, the flow speed of the fluid can be increased, and the fluid can resist the reverse flow.

It should be noted that the thickness of the hub convex surface 21 gradually increases along the flow direction of the flow channel 4, and the increasing thickness is not particularly limited in this embodiment. Because the length of the flow channel 4 is different, and the number of the arranged blades 1 is different, the length and the thickness of the hub convex surface 21 are different, so that the thickness of the hub convex surface 21 can be adjusted according to parameters such as the width of the flow channel 4 formed among the blades 1, the total length of the flow channel 4 and the like, and the overall performance is higher.

In the embodiment of the invention, the hub 2 close to one side of the suction surface 12 of the blade 1 is gradually thickened along the direction of the flow channel 4 to form a hub convex surface 21, the thickened position of the hub convex surface 21 is 50-100% of the total length of the flow channel 4 along the flow direction, and a convergent shape is formed, so that the flow channel area of the fluid can be reduced; in the circumferential direction, the thickened position of the hub convex surface 21 is more inclined to the area from the suction surface 12 to the middle 50% of the flow passage 4, so that the flow speed of the fluid close to the suction surface 12 can be increased. By arranging the convex surface 21 of the hub, the flow passage area of the fluid on one side of the suction surface 12 is reduced, when the fluid enters a wake flow region from a jet flow region from top to bottom, the kinetic energy of the fluid can be improved, the reverse pressure gradient is resisted, the wake flow generation and outlet mixing loss are reduced, and the performance of the compressor is improved.

EXAMPLE III

The embodiment of the invention also provides an air compressor which comprises the impeller structure in any one of the embodiments.

The impeller structure provided by the embodiment of the present invention may include a full main blade form, or may include a main blade form and a splitter blade form, and is not particularly limited.

In the embodiment of the invention, the hub 2 close to one side of the suction surface 12 of the blade 1 is gradually thickened along the direction of the flow channel 4 to form a hub convex surface 21, the thickened position of the hub convex surface 21 is 50-100% of the total length of the flow channel 4 along the flow direction, and a convergent shape is formed, so that the flow channel area of the fluid can be reduced; in the circumferential direction, the thickened position of the hub convex surface 21 is more inclined to the area from the suction surface 12 to the middle 50% of the flow passage 4, so that the flow speed of the fluid close to the suction surface 12 can be increased. By arranging the convex surface 21 of the hub, the flow passage area of the fluid on one side of the suction surface 12 is reduced, when the fluid enters a wake flow region from a jet flow region from top to bottom, the kinetic energy of the fluid can be improved, the reverse pressure gradient is resisted, the wake flow generation and outlet mixing loss are reduced, and the performance of the compressor is improved.

The terms "including" and "having," and any variations thereof, in the description and claims of this application and the description of the above figures are intended to cover non-exclusive inclusions. The terms "first," "second," and the like in the description and claims of this application or in the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by a person skilled in the art that the embodiments described herein can be combined with other embodiments, the connection between the motor and the control means being an electrical connection.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An impeller structure, comprising: a plurality of blades, wheel hub and wheel back boss, the blade sets up in the wheel hub periphery, wheel back boss is located wheel hub bottom center, just the blade wheel hub with wheel back boss integrated into one piece, the pressure surface, the suction surface of blade and the wheel hub surface forms the runner, wherein wheel hub between the blade is provided with one on the surface and extends to the wheel hub convex surface of runner tail end.

2. The impeller structure of claim 1, wherein the hub convexity is a convex structure having a thickness that increases gradually in a direction of flow of the flow channel.

3. An impeller structure according to claim 1 or 2, wherein said hub convexity is provided in said flow path offset to the side of said suction surface.

4. An impeller structure according to claim 1 or 2, wherein the hub convex surface increases in thickness in the direction of flow of the flow channel, and the position where the thickness increases in the direction of flow of the flow channel is the middle position of the flow channel to the end position of the flow channel.

5. An impeller structure according to claim 2, wherein said hub convexity increases from a thickness in the direction of flow of said flow channel to a convergence at the trailing end of said flow channel.

6. An impeller structure according to claim 2, wherein said hub convex surface is located in an area offset by 50% from said suction surface of said blade in a circumferential direction of said hub.

7. An impeller structure according to claim 6, wherein the circumferential extent of said hub convexity in the circumferential direction of said hub occupies 50% of the area of said flow passage.

8. An impeller structure according to claim 2, wherein the thickening start position of the convex surface of the boss is 50% to 100% of the position of the start end of the flow passage in the flow direction of the flow passage.

9. An impeller structure according to claim 8, wherein the thickening start position of the convex surface of the hub is 80% to 100% of the position of the start end of the flow passage.

10. A compressor comprising an impeller structure according to any one of claims 1 to 9.

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