阅读说明：本技术 一种开式向心涡轮 (Open centripetal turbine ) 是由 陈化 王宇 于 2020-12-17 设计创作，主要内容包括：本发明公开了本发明提供一种开式向心涡轮,包括：转子和蜗壳,所述蜗壳具有蜗壳出口,所述蜗壳出口与压缩腔连通,所述转子在所述压缩腔内转动,所述压缩腔前端敞开,后端设有封闭件,所述封闭件的内壁面为所述压缩腔的后端面,所述蜗壳出口的后侧面与所述封闭件的内壁面平滑连接。所述蜗壳出口的后侧面与所述封闭件的内壁面在同一平面内。本发明公开的一种开式向心涡轮,使气流的降速和漩涡现象大大改善,降低了气动效率损失,使开式向心涡轮的效率大大提高。(The invention discloses an open centripetal turbine, comprising: the rotor rotates in the compression cavity, the front end of the compression cavity is open, the rear end of the compression cavity is provided with a sealing piece, the inner wall surface of the sealing piece is the rear end surface of the compression cavity, and the rear side surface of the volute outlet is smoothly connected with the inner wall surface of the sealing piece. The rear side of the volute outlet is in the same plane as the inner wall surface of the closure. The open centripetal turbine disclosed by the invention has the advantages that the speed reduction and vortex phenomena of airflow are greatly improved, the pneumatic efficiency loss is reduced, and the efficiency of the open centripetal turbine is greatly improved.)

1. An open centripetal turbine, comprising: the rotor and the volute are provided with a volute outlet (1), the volute outlet (1) is communicated with the compression cavity, the rotor rotates in the compression cavity, the front end of the compression cavity is open, the rear end of the compression cavity is provided with a sealing piece (2), the inner wall surface of the sealing piece (2) is the rear end surface of the compression cavity, and the rear side surface of the volute outlet (1) is smoothly connected with the inner wall surface of the sealing piece (2).

2. An open centripetal turbine according to claim 1, wherein the back side of said volute outlet (1) is coplanar with the inner wall surface of said enclosure (2).

3. An open centripetal turbine according to claim 1, wherein said rotor comprises a blade and a disk, said blade having a tip radius of rotation greater than a radius of said disk.

4. An open centripetal turbine according to claim 1, wherein a first gap (3) is present between the back of said blades and the inner wall surface of said enclosure (2), a second gap (4) is present between the back of said disk and the inner wall surface of said enclosure (2), said first gap (3) being equal to said second gap (4).

5. An open centripetal turbine according to claim 1, wherein said closing element (2) is a heat-insulating plate.

Technical Field

The invention relates to the field of turbines, in particular to an open centripetal turbine.

Background

The centripetal turbine can be divided into a full-back-plate centripetal turbine and an open-type centripetal turbine according to different types of rotor back plates. The open centripetal turbine removes partial materials of a wheel disc on the basis of a full-back-disc centripetal turbine, so that the mass and the rotational inertia of a rotor are greatly reduced. Therefore, the open type centripetal turbine is lower in thermal stress and mechanical stress when in work, longer in service life and more practical in application under high-load working conditions.

However, the loss of aerodynamic efficiency of open centripetal turbines is large.

Disclosure of Invention

The invention provides an open centripetal turbine, which solves the problems.

An open centripetal turbine, comprising: the rotor rotates in the compression cavity, the front end of the compression cavity is open, the rear end of the compression cavity is provided with a sealing piece, the inner wall surface of the sealing piece is the rear end surface of the compression cavity, and the rear side surface of the volute outlet is smoothly connected with the inner wall surface of the sealing piece.

Further, a rear side of the volute outlet is in the same plane as an inner wall surface of the closure.

Further, the rotor comprises a blade and a wheel disc, wherein the tip rotating radius of the blade is larger than the radius of the wheel disc.

Further, a first gap exists between the back of the blade and the inner wall surface of the closing member, a second gap exists between the back of the disk and the inner wall surface of the closing member, and the first gap and the second gap are equal.

Further, the closing member is a heat insulating plate.

The open centripetal turbine disclosed by the invention has the advantages that the speed reduction and vortex phenomena of airflow are greatly improved, the pneumatic efficiency loss is reduced, and the efficiency of the open centripetal turbine is greatly improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic view of a prior art full back disk turbine configuration;

FIG. 2 is an enlarged view of a portion of a prior art full back disk turbine volute outlet;

FIG. 3 is a prior art flow diagram of a full back disk turbine rotor flowpath;

FIG. 4 is an entropy distribution plot of a prior art full back disk turbine rotor;

FIG. 5 is a schematic view of a prior art open turbine configuration;

FIG. 6 is an enlarged partial view of the outlet of the volute of the prior art open turbine configuration;

FIG. 7 is a prior art flow diagram of an open turbine rotor flowpath;

FIG. 8 is an entropy profile of a prior art open turbine rotor;

FIG. 9 is a schematic view of an open turbine configuration according to the present invention;

FIG. 10 is an enlarged view of a portion of the outlet of the volute of the open turbine configuration of the present invention;

FIG. 11 is a flow diagram of an open turbine rotor flowpath according to the present invention;

FIG. 12 is an entropy profile of an open turbine rotor according to the present invention;

FIG. 13 is a graph of aerodynamic efficiency for a prior art heat shield having different groove depths relative to the volute outlet.

In the figure: 1. a volute outlet; 2. a closure; 3. a first gap; 4. a second gap.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the turbine structure in the prior art, an airflow enters a compression chamber from a volute to drive a rotor to rotate and flows out along the axial direction of the rotor, an outlet of the volute is communicated with the compression chamber, hereinafter, the direction of the airflow flowing out along the axial direction of the rotor is referred to as "front", the opposite direction of the airflow flowing out along the axial direction of the rotor is referred to as "rear", therefore, the side surface of the volute relatively to the rear is referred to as "rear side", and the surface of a closing member facing the rotor is positioned in the compression chamber and is referred to as.

The reason for the great aerodynamic efficiency loss of the open centripetal turbine is obtained through analysis.

Fig. 1 and 4 are schematic views of a turbine structure in the prior art, which are respectively a full-back disc turbine and an open turbine. In the prior art, in order to improve the operation of the turbine, the incoming flow in the volute needs to act on the rotor blades as much as possible, so the volute outlet is set to be completely towards the blades of the rotor, that is, the hub of the rotor is flush with the rear side of the volute outlet in the full back-disk turbine, and the rotation plane of the back disk of the rotor is flush with the rear side of the volute outlet in the open turbine. The two structures enable the volute outlet to be completely towards the blades of the rotor, and further enable the rotor to convert kinetic energy into output work as much as possible. However, in order to prevent the rotor from rubbing against the closing member provided in the direction of the back surface of the rotor, i.e., the heat insulating plate needs to be disposed offset from the rear side surface of the turbine outlet, i.e., the heat insulating plate is retracted in the axial direction with respect to the rear side surface of the volute outlet.

Since the heat shield is axially set back relative to the rear side of the volute outlet, a stepped configuration is created. In prior art full back disk turbines, the hub face of the rotor and the volute outlet back side are flush. Due to the existence of the full back plate structure, the incoming flow of the volute does not have obvious flow change when passing through the step structure, and can smoothly flow into the rotor channel. In prior art open turbines, the rotor back disk face of the rotor is flush with the volute outlet back side face. Unlike full back-disk structures, the back-disk of open turbine rotors is completely cut in the high radius region, and significant flow separation occurs when the incoming flow of the volute passes through the stepped structure. The flow separation causes the air flow to generate obvious deceleration and even to form vortex, and the deceleration and the vortex of the air flow bring about the increase of entropy, thereby causing efficiency loss. Meanwhile, the back disc of the open turbine rotor is of an open structure, so that air flow can directly enter a back gap through an open part, the loss is further enlarged, and the efficiency of the turbine is further influenced.

In order to improve the airflow deceleration and swirl phenomenon in the open turbine, it is necessary to reduce the flow separation of the airflow at the step structure, and this phenomenon can be improved by making the rear side of the volute outlet smoothly connected to the heat insulating plate. The smooth connection of the two parts greatly improves the speed reduction and vortex phenomena of the airflow, and when the two parts are on the same plane, the speed reduction and vortex improvement effect is optimal. The loss of pneumatic efficiency is reduced, and the efficiency of the open centripetal turbine is improved.

As shown in fig. 1 and 2, a full back disk centripetal turbine includes: the rotor rotates in the compression cavity, the front end of the compression cavity is open, the rear end of the compression cavity is provided with a heat insulation plate, and airflow flows into the compression cavity from the outlet of the volute and then flows out from the front end of the compression cavity. In the flowing process of the air flow, the air flow passes through the junction of the volute and the heat insulation plate, in order to enable the air flow to directly act on the blades of the rotor, the heat insulation plate is arranged behind the rear side face of the outlet of the volute, namely the heat insulation plate forms a groove relative to the rear side face of the outlet of the volute, and therefore the rotor can be arranged backwards, and the air flow can directly act on the blades of the rotor.

As shown in fig. 3 and 4, the rear side of the volute outlet and the heat insulation plate form a step-like structure because the heat insulation plate forms a groove relative to the rear side of the volute outlet. However, since the hub surface of the rotor is flush with the rear side surface of the volute outlet and the full back plate structure of the rotor is very close to the step structure, the airflow coming out of the volute can smoothly cross the step and flows into the compression chamber, and in fig. 3, the color change at the position a is uniform, which indicates that the airflow is stable. In fig. 4, the color change at the B position is uniform, which indicates that the entropy distribution of the entire flow channel is relatively uniform.

As shown in fig. 5 and 6, an open centripetal turbine is adopted, the radius of rotation of the blade tip of each blade is larger than that of the rotor back disc, so that openings exist among the blades, the front and the back of the rotor are communicated, and air flow can flow into the rotor back gap from the openings. At the volute outlet, flow separation and stall of the airflow past the steps can occur, and due to the presence of the openings, the separation and stall also affect the flow field in the rotor channels, and even vortices can form near the steps. These effects all lead to an increase in entropy and a loss of aerodynamic efficiency, as shown in fig. 7 and 8, where the C position in fig. 7 is colored more clearly to indicate flow separation and stall, and the D position in fig. 8 is colored lighter to indicate an increase in entropy.

In order to reduce the influence of the airflow passing through the steps, the rear side surface of the volute outlet is smoothly connected with the rear end surface of the compression chamber. This reduces the swirl that occurs when the fluid passes through the step structure.

Further, as shown in fig. 9 and 10, the rear side surface of the volute outlet is in the same plane with the rear end surface of the compression chamber, that is, the forward plane of the heat insulation plate is flush with the rear side surface of the volute outlet, so that the groove formed by the heat insulation plate relative to the rear side surface of the volute outlet is eliminated. The invention eliminates the influence of the step structure on the air flow, so that the air flow can smoothly flow into the rotor flow channel (compression chamber) from the volute.

A first gap 3 exists between the back of the blade and the inner wall surface of the closing member 2, a second gap 4 exists between the back of the disk and the inner wall surface of the closing member 2, and the first gap 3 and the second gap 4 are equal. The space at the back of the impeller is uniform and flat, the airflow is not easy to disturb, and the airflow flowing of the rotor is not influenced.

We analyzed the effect of the grooves on aerodynamic efficiency under different operating conditions. Under conditions where the U/C values (U is blade tip speed, C is outlet isentropic jet velocity, different U/C values represent different operating conditions) were 0.5 and 0.71 respectively, the fluid mass flow in the differently configured turbines is shown in the following table:

it can be seen from the table that the fluid mass flow in the turbines of different configurations remains substantially constant.

However, as shown in FIG. 13, the aligned configuration of the volute and the heat shield is more aerodynamic efficient than the non-aligned configuration of four different groove depths, and the deeper the groove depth, the greater the loss of efficiency and the lower the aerodynamic efficiency.

Through the above analysis, the embodiment arranges the heat insulation plate on the forward plane, that is, the inner wall surface is flush with the rear side surface of the volute outlet, so that the rear side surface of the volute outlet and the rear end surface of the compression cavity are in the same plane, as shown in fig. 11 and 12, the color change of the position E is uniform, the streamline of the rotor flow channel is smooth and stable, the position D has no color highlight display, the change is uniform, and the entropy value is lower than that of a non-flush structure.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.