RU2518703C2 - Multistage radial turbine - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed turbine comprises rotary shaft, set of rotor blades, set of nozzles and connection channel. Rotor blades are fitted on the shaft and spaced apart thereat to direct working fluid flow in, in fact, lengthwise direction. Nozzles are arranged at top upstream part of every rotor blade to accelerate working fluid flow. Connection section has curved U-like section, blade section and inverse bend section. Said curved U-like section deflects working fluid flow from rotor blade radially outward in lengthwise direction. Blade section comprises a set of blades deflecting working fluid flow in direction of blades rotation, from said curved U-like section radially outward. Said inverse bend section deflects the flow radially inward, flow flowing from blade section radially outward. Said curved U-like section features cross-section area nearby blade section, downstream of section end, not exceeding 0.8-0.9 of its across-section area nearby the end proximate to radial turbine rotor blade, at its upper side.

EFFECT: decreased leaks via turbine shaft support bearings.

2 cl, 2 dwg

Description

Technical field

The present invention relates to multistage radial turbines.

State of the art

The design of the radial turbine is characterized by the presence of a group of centrifugal blades mounted on a hub mounted on a rotary shaft, and these blades are exposed to air or gas, which is a working medium that extends inward in the radial direction from the outside, moving through the space between essentially parallel circular plates used as a flow channel, and which acts on centrifugal blades, involving the hub in rotation, and then leaves essentially in p odolnom direction of the shaft.

Since a high degree of expansion can be achieved even by means of a single-stage design, precisely one-stage radial turbines are usually used in the prior art.

In order to efficiently use the energy of the working medium, in which a large pressure drop is accompanied by a significant thermal drop, it was proposed to use a multi-stage configuration in a radial turbine, i.e. use the work environment in several stages.

For example, in Patent Document 1, it is proposed to arrange several radial turbines in a row so that the flow of the working medium coming out of one radial turbine enters the inlet of the next radial turbine, saving the energy of the working medium. In this case, all radial turbines have their own shafts with different speeds of rotation, and the work is performed due to the rotation of the individual shafts.

References to cited documents

Patent document 1: Japanese patent application for which no examination was conducted, Publication No. Sho 59-79096.

SUMMARY OF THE INVENTION

Object of the invention

In the design described in Patent Document 1, each radial turbine has its own rotary shaft, so the number of bearings and shaft seals increases. Because of this, losses in bearings and losses due to leaks increase, which makes it impossible to efficiently convert the energy of a working medium under high pressure into kinetic energy of rotation.

In particular, if kinetic energy is generated to carry out some operation, the rotation force is transmitted from the individual output shafts to the shaft performing this operation, for example, by gearing; this raises the problem that the turbine design becomes cumbersome.

In view of the above circumstances, the present invention is to develop a multi-stage turbine, which allows to reduce the number of bearings used and increase the conversion efficiency.

The solution of the problem

To solve the above problem, the present invention provides the following solution.

According to a key aspect of the present invention, there is provided a multi-stage radial turbine, comprising: a single rotary shaft; a group of rotor blades of the radial turbine, which are attached to the rotary shaft through the gaps and direct the flow of the working medium coming in the radial direction from the outside, essentially in the longitudinal direction of the shaft; a group of nozzles mounted separately on the upstream side of each rotor blade and accelerating the flow of the working medium in the direction of rotation; a connecting channel providing communication between the outlet portion of the rotor blade of the front stage and the upstream side of the nozzle of the rear stage, the connecting channel having a curved U-shaped portion that deflects the flow of the medium flowing in the longitudinal direction of the shaft from the rotor blade outward in the radial direction ; a blade section containing a group of deflecting blades deflecting the flow of the working medium in the direction of rotation of the rotor blades with the flow of the working medium from the curved U-shaped portion outward in the radial direction; and a backward bending portion that deflects inward in the radial direction a stream exiting the blade portion, thereby causing an outward swirl in the radial direction.

In accordance with the proposed invention, the flow of the working medium coming in the radial direction from the outside is accelerated by the nozzle in the direction of rotation and enters the outer peripheral part of the rotor blade of the radial turbine. The working medium entering the rotor blade leaves the specified rotor blade in the longitudinal direction of the shaft, passes through a curved U-shaped section, where it deviates outward in the radial direction, and then deviates under the action of deflecting blades in the direction of rotation of the rotor blade of the radial turbine, this outward in the radial direction while passing through the blade section. The working medium, which leaves the blade section in the radial direction with an outward swirl, passes through the reverse bending section, where it deviates inward in the radial direction and then enters the next stage nozzle from the outside in the radial direction. The flow of the working medium cyclically undergoes the described processes, and then leaves the rotor blades of the last stage, for example, essentially in the longitudinal direction of the shaft. In this case, the rotation of each rotor blade is transmitted to a single rotary shaft, ensuring its rotation.

Since the group of rotor blades of the radial turbine is in this way attached to a single rotary shaft through the gaps, bearings and seals are required for only one rotary shaft, and therefore, their number can be reduced compared with the case of using a group of rotary shafts.

Due to the fact that losses in bearings and losses due to leaks are reduced, the energy of the working medium under high pressure will be effectively converted into kinetic energy of rotation.

In addition, the rotor blades of the radial turbine and the rotary shaft can have a design similar to a conventional design, but it becomes possible to prevent the increase in the size of these elements of a multistage radial turbine.

According to one embodiment of the invention, the curved U-shaped section is designed so that the cross-sectional area of the channel at the end closest to the blade section on its downstream side is smaller than the cross-sectional area of the channel at the end closest to the rotor blade of the radial turbine, on its upstream side.

Since the curved U-shaped section is designed so that the cross-sectional area of the channel at the end closest to the blade section, on its downstream side, is smaller than the cross-sectional area of the channel at the end closest to the rotor blade of the radial turbine, on its upstream side, it becomes possible to accelerate the flow of the working medium in the specified curved U-shaped section.

Due to this, flow stall can be reduced due to the influence of low flow rate zones that may be present at the outlet portions of the rotor blade of the radial turbine.

According to a preferred embodiment of the invention, said channel cross-sectional area on its downstream side does not exceed 0.8-0.9 of the channel cross-sectional area on its upstream side.

Zones of low flow velocity that can occur in the outlet sections of the rotor blades of the radial turbine usually occupy 10-20% of the channel area in these sections.

Due to the acceleration of the flow of the working medium in the curved U-shaped section provided by the invention by at least 10-20%, it is possible to reduce the influence of the low flow rate zones.

In a preferred case, the deflecting blades are in the form of an involute.

This configuration makes it possible to reduce the difference between the channel area at the inlet section between the deflecting blades of the blade section and the channel area at the output section.

Accordingly, it is possible to reduce losses associated with deceleration and deviation of the medium in the blade section.

Provided technical result

Since, according to the present invention, the rotor blades of the radial turbine are connected through the gap to one rotary shaft, bearings and seals are required for only one rotary shaft, therefore, their number will be reduced compared with the case of using multiple rotary shafts.

Based on the foregoing, losses in bearings and losses resulting from leaks are reduced, which means that the energy of the working medium under high pressure is effectively converted into kinetic energy of rotation.

In addition, the rotor blades of the radial turbine and the rotary shaft can have a design similar to a conventional design, but it becomes possible to prevent the increase in the size of these elements of a multistage radial turbine.

Brief Description of the Drawings

Figure 1 schematically depicts in section a fragment of a multi-stage single-shaft radial turbine, corresponding to one of the variants of the invention.

Figure 2 shows a section taken along the line X-X shown in Figure 1.

Description of the invention

Next, with reference to figures 1 and 2, the proposed multi-stage single-shaft radial turbine 1 is described.

Figure 1 schematically depicts in section a fragment of the proposed multistage single-shaft radial turbine. Figure 2 shows a section taken along the line X-X shown in Figure 1.

A multi-stage single-shaft radial turbine 1 has a rotary shaft 3, a group, for example two, of rotor blades 5, a housing 7 and a connecting flow channel 9.

The rotary shaft 3 is held on the housing 7 by one end placed in a radial bearing (not shown), while the other end is held by a radial bearing (not shown) and a thrust bearing (not shown).

A group of rotor blades 5 are provided in the turbine, which are spaced at intervals in the longitudinal direction L of the rotary shaft 3 and which direct the flow of the medium flowing in the radial direction K from the outer peripheral side, essentially in the specified longitudinal direction L of the rotary shaft.

The rotor blades 5 of the radial turbine have hubs 11 attached to the rotary shaft 3, a group of centrifugal blades 13, mounted on the hubs 11 at regular intervals in the circumferential direction, and screens 15 attached to the ends of these blades 13.

In the rotor blades 5 of the radial turbine, gas channels are provided, i.e. channels through which gas (working medium) passes, limited by said hubs 11, blades 13 and shields 15. Sections of these gas channels remote from the rotary shaft 3 are used as gas inlet sections 21, while the gas channels located near the rotary shaft 3, are used as sections 23 of the release of gas.

A toroidal inlet channel 17 extending in the radial direction K is provided in a part of the housing 7 located on the outside of the gas inlet portions 21. The inlet channel 17 is shaped so that gas flows therein in the radial direction K from the outside.

On the downstream side of the inlet channel 17, or, equivalently, on the upstream side of the rotor blades 5 of the radial turbine, an aerodynamic nozzle 19 is installed that accelerates the gas flow in the direction of rotation R.

The connecting channel 9 is a channel in the housing 7, providing communication between the gas exhaust portions 23 of the front stage rotor blades 5 and the upstream side of the rear stage nozzle 19.

The connecting channel 9 has a curved U-shaped section 25, which deflects the gas stream entering in the longitudinal direction L of the shaft from the rotor blade 5, outward in the radial direction K, the blade section 29 containing several deflecting blades 27, deflecting the gas stream in the direction of rotation R rotor blades 5 with a gas flow from a curved U-shaped portion 25 outward in the radial direction K, and a section 31 of the reverse bend, which deflects inward in the radial direction K the gas leaving the blade part stka 29, thus causing a twist in the outward radial direction K.

The cross-sectional area A2 of the channel at the end of the curved U-shaped portion 25 closest to the blade portion 29, on its downstream side, is at least 0.8-0.9 of the cross-sectional area A1 of the channel at the end closest to the rotor blade 5 radial turbine, on its upstream side. In other words, the channel is created in such a way that the cross-sectional area A2 on its downstream side is smaller than the cross-sectional area A1 on its upstream side.

The specified ratio is determined taking into account the zones T of low flow velocity, which are present at least in the output sections of the rotor blades 5 of the radial turbine. Zones T of a low flow rate usually occupy 10-20% of the area of the outlet channel section, i.e. area A1 of the channel of the rotor blades 5 on the upstream side.

Although in the preferred case, the channel area A2 on the downstream side is smaller than the channel area A1 on the upstream side, it can be substantially equal to or even exceed it, depending on the usage.

As shown in FIG. 2, the deflecting vanes 27 of the blade portion 29 are in the form of an involute.

In this case, a significant reduction in the difference between the channel area A3 in the input section and the channel area A4 in the output section between the deflecting vanes 27 of the blade section 29 is achieved compared to the difference between the channel area A5 in the input section and the channel area A6 in the output section between linearly expanding deflecting blades 33, shown in figure 2 by a dash-dot line with two points.

Although in the preferred case, the deflecting vanes 27 are in the form of an involute, this condition is not mandatory, and they can have any suitable shape.

The following describes the principle of operation of a multi-stage single-shaft radial turbine 1, made according to the above disclosed embodiment of the invention.

The gas stream G1 coming from a gas source (not shown) into the inlet channel 17 of the first stage passes through the channel and flows inward in the radial direction K into the nozzle 19 from the outside.

The nozzle 19 accelerates this gas flow G1 in the circumferential direction R and brings it to the gas inlet portions 21 located on the outer peripheral part of the rotor blades 5 of the radial turbine.

The gas entering the rotor blade 5 of the radial turbine expands as it passes through the gas channel bounded by the hub 11, centrifugal blades 13 and the screen 15. Due to this expansion, the blades 13 are driven in rotation in the direction of rotation R. Due to this movement of the blades 13, the hub 11 is involved in rotation in the direction R and rotates the rotary shaft 3.

A gas stream exiting in the longitudinal direction L of the shaft from the rotor blade gas discharge portions 23 passes through a curved U-shaped portion 25 and deviates outwardly in the radial direction K.

Moreover, due to the fact that the cross-sectional area A2 of the curved U-shaped portion 25 on its downstream side is at least 0.8-0.9 of the cross-sectional area A1 on its upstream side, the gas flow passing through the curved The U-shaped portion 25 is accelerated, for example, by at least 10-20%, in accordance with the reduction of the channel area.

Although typically there are low flow rate zones T in front of the gas discharge portions 23 of the rotor blade 5 and behind these portions, which occupy 10-20% of the channel area, these zones T can be substantially eliminated since at least a curved U-shaped portion 25 is achieved a sufficient level of acceleration. In other words, the effect of zones T of low flow rate can be reduced.

Due to the fact that in this way it is possible to reduce the effect of zones T of a low flow rate, by concentrating these zones arising in the gas discharge sections 23 of the rotor blade 5, it is possible to reduce the stall due to curvature of the surface of the screen 15 on the downstream side.

If the area A2 of the channel on the downstream side is less than 0.8-0.9 of the area A1 of the channel on the upstream side, flow stall can be further reduced; therefore, the curvature of individual sections can be reduced even more.

Due to this measure, the shaft in a multi-stage configuration can have a smaller overall length, and therefore the total length of the entire single-shaft radial turbine 1 will become smaller, i.e. this radial turbine 1 will be more compact.

When the gas stream further passes through the blade section 29, it deviates in the direction R of rotation of the rotor blade 5 of the radial turbine and is directed outward in the radial direction K under the action of the deflecting blades 27.

Moreover, since the deflecting vanes 27 are in the form of an involute, the difference between the area A3 in the inlet section of the channel between the deflecting vanes 27 and the area A4 in the outlet section will be small. Due to this, the losses in the blade section 29 associated with the deceleration of the gas stream and its deviation will be reduced.

In addition, by adjusting the angular position of the deflecting vanes 27, it is possible to adjust the flow angle at the inlet to the nozzle 19 on the downstream side. So, if you give the angle of the flow at the entrance to the nozzle 19 a value of from 40 to 50 degrees in the circumferential direction, the collision loss at the entrance to the nozzle 19 can be reduced.

The flow exiting from the blade section 29 in the radial direction K to the outside with a swirl passes through the reverse bending section 31, deviates inward in the radial direction K and is forced to flow in the radial direction K into the input channel 17 of the next stage from the outside.

The gas stream G2 coming from section 31 with a reverse bend passes through the inlet channel 17 and flows into the nozzle 19 inward in the radial direction K from the outside.

The nozzle 19 accelerates this gas flow G2 in the circumferential direction R and delivers it to the gas inlet portions 21 located on the outside of the rotor blade 5 of the radial turbine.

The gas entering the rotor blade 5 of the radial turbine expands as it passes through the gas channel bounded by the hub 11, centrifugal blades 13 and the screen 15. Due to this expansion, the blades 13 are driven in rotation in the direction of rotation R. Due to this movement of the blades 13, the hub 11 is involved in rotation in the direction R and rotates the rotary shaft 3.

The gas stream exiting in the longitudinal direction L of the shaft from the sections 23 of the gas outlet of the rotor blades passes through an outlet channel (not shown) and is released into the space outside the radial turbine 1.

Since the rotor blades 5 of the radial turbine are connected in this way through the gap to one rotary shaft 3, bearings and seals are required only for this one rotary shaft 3, so their number will be reduced compared with the case of using multiple rotary shafts.

Due to the fact that losses in bearings and losses due to leaks are reduced, the energy of the working medium under high pressure is effectively converted into kinetic energy of rotation. In addition, the thermal difference of the working medium can be converted into kinetic energy of rotation by means of one single-shaft radial turbine.

The rotor blades 5 of the radial turbine and the rotary shaft 3 can have a design similar to the conventional design, but it becomes possible to prevent the increase in the size of these elements of the single shaft radial turbine 1.

The present invention is not limited to the embodiment described above - the scope of its legal protection includes various modifications that do not contradict the essence of the present invention.

For example, despite the fact that in the presented embodiment two stages of rotor blades 5 of a radial turbine are used, their number can be increased to three or more. In this case, communication between adjacent rotor blades 5 will be provided by connecting channels 9.

Item Numbers

1 - single shaft radial turbine

3 - rotary shaft

5 - rotor blade of a radial turbine

9 - connecting channel

19 - nozzle

25 - curved U-shaped section

27 - deflecting blade

29 - blade section

31 - section reverse bending

A1 - channel cross-sectional area on the upstream side

A2 - channel cross-sectional area on the downstream side

K - radial direction

L is the longitudinal direction of the shaft

R is the direction of rotation.

Claims (2)

1. A multi-stage radial turbine containing:
single rotary shaft;
a group of rotor blades of the radial turbine, which are attached to the rotary shaft through the gaps and direct the flow of the working medium coming in the radial direction from the outside, essentially in the longitudinal direction of the shaft;
a group of nozzles mounted separately on the upstream side of each rotor blade and accelerating the flow of the working medium in the direction of rotation;
a connecting channel providing communication between the outlet portion of the rotor blade of the front stage and the upstream side of the nozzle of the rear stage,
moreover, the connecting channel has a curved U-shaped section, which deflects the flow of the working medium coming in the longitudinal direction of the shaft from the rotor blades, outward in the radial direction;
a blade section containing a group of deflecting blades deflecting the flow of the working medium in the direction of rotation of the rotor blades with the flow of the working medium from the curved U-shaped portion outward in the radial direction;
and a reverse bending portion that deflects inwardly in the radial direction a stream swirling and exiting from the blade portion outwardly in the radial direction,
moreover, the curved U-shaped section is made so that the cross-sectional area of the channel at the end closest to the blade section, on its downstream side, is smaller than the cross-sectional area of the channel at the end closest to the rotor blade of the radial turbine, on its upstream side
wherein said channel cross-sectional area on its downstream side does not exceed 0.8-0.9 of the channel cross-sectional area on its upstream side. 2. The turbine according to claim 1, in which the deflecting blades are in the form of an involute.

Images