Radial-axial hydraulic machine

FIELD: machine building.

SUBSTANCE: hydraulic machine comprises an inner and an outer separating circular hydrodynamic seals 8 and 9, arranged into each or one of cavities around an impeller 2 - between the impeller 2 and a cover 5 and between the impeller 2 and a foundation ring 6. The outer separating seal 8 is located in the area of the peripheral zone of the impeller 2, and the inner one 9 - between the outer separating seal 8 and a seal 7, which limits leaks into a suction pipe. Two rings 10 and 11, which form the inner separating seal 9, have a Z-shaped or an angular profile in the cross section and are installed so that free shelves of their cross sections cover each other. Each cavity, where separating seals 8 and 9 are installed, is separated into two chambers 12 and 14. The external chamber 14 is equipped with an input 17 for compressed gas supply.

EFFECT: invention provides for squeezing out water from the peripheral zone of the impeller during operation of the hydraulic machine in the turbine or pump mode and reduction of energy losses for disc friction.

1 dwg

 

The present invention relates to the field of power engineering, in particular to the design of radial-axial hydraulic machines designed primarily for high pressure drops, i.e. at high pressure.

When working radial-axial hydraulic machines have substantial energy losses due to disc friction outer surfaces of the impeller on the water, which greatly reduces the efficiency of the hydraulic machine. The outer surfaces of the impeller is the disc surface of the impeller facing the stator parts of a hydraulic machine. The disk is called the upper rim and the lower rim of the impeller.

About the losses on the disk friction can be judged from the following.

According to well-known from theory of hydraulic machines dependencies to determine the value of the internal mechanical efficiency of hydraulic machines, for example machines for low speed, used for pressures of about 500 meters, the value of mechanical efficiency in pumping mode is 93%. This means that in this case, the amount of losses on the disk friction is approximately 7% of the useful hydraulic energy.

In General, the calculated data and the test results show that the greatest loss to the disk friction occur when working vasocon pornoi hydraulic machines in pumping mode approximately 7%. When working in the turbine mode, the amount of losses on the disk friction is less than approximately 5%.

From theory of calculation of hydraulic machines it is known that the magnitude of the power loss on the disk friction is determined by the formula ΔP=k·ρ·ω3·D5where k is a constant coefficient, ρ is the density of the medium, ω is the rotor speed of the hydraulic machine, D is the diameter of the carrier or covering disk of the impeller.

The above relationship shows that the magnitude of the power loss on the disk friction ΔP is directly proportional to the density of the medium ρ, which implies that it is possible to achieve a considerable reduction of losses on disk friction in the case of exclusion of the aquatic environment from the space around the outer surfaces of the impeller and fill the space with compressed air (gas), since the density of air (gas) is hundreds of times less than the density of water.

The problem of reducing losses to the disk friction is particularly relevant for high-pressure reversible pump-turbines. Unfortunately, at present it is not known about effective solutions that significantly reduce losses on disk friction during operation of the hydraulic machine in the turbine or pump modes. The solution to this problem would overall significantly increase the efficiency of radial-axial, hydraul the ical machines.

Known tubular-blade impeller [Patent RU 2345243 C1, F03B 3/12, date of publication - 27.01.2009,], to solve the problem of increasing efficiency by reducing friction losses due to elimination of contact with the external surfaces of the wheel with water.

Known tubular-blade impeller includes blades and the shaft, on which is seated the upper and lower bearing disks. Between the disks installed tubular blades, curved in the form of knees. The outputs of the tubular blade is oriented horizontally tangent to the circumference of the lower disk. The blades are made in the form of pipe segments, the input upper sections which are arranged vertically.

Due to the fact that the entire discharge flow takes place only inside the tubular blade, leaving the outer surfaces of the blades and other surfaces of the impeller dry, no contact with the external surfaces of the wheel with water, according to the conclusions of the author reduces friction losses.

However, with the exception of friction of the thread on the outer surface of the impeller in this technical solution are friction losses in the tubular channels of the blades, and, in addition, the impeller cannot be applied in a powerful high-pressure hydraulic machines due to insufficient capacity and efficiency.

As a prototype announced aemula technical solutions proposed to choose the radial-axial hydraulic machine ["Hydraulic turbine", Industry directory rie, Informenergo, M., 1985, s, RES], which contains the impeller disk mounted on the shaft of the turbine, the guide apparatus, the suction pipe and the stator nodes hydraulic machines - the cover and the base ring. In the area around the impeller is formed with two cavities: one between the impeller and the cover of the hydraulic machine, and the other between the impeller and the base ring. In these cavities posted by seals, which when the unit limit water leakage in the suction pipe from the space between the impeller and guide vanes. In the known construction is provided by the possibility of compressed air flowing in the hydraulic part of the machine, namely in the space between the impeller and cover performed when the hydraulic machine in the synchronous compensator (RIC labeled "air supply when operating in mode IC").

The application of this technical solution provides full release of water from areas in and around the impeller during operation of the hydraulic unit in the synchronous compensator (SC) and can dramatically reduce hydraulic, including disk, losses during rotation of the impeller in the mode of the IC, since the density of air hundreds of times less than the density of water, and according to known dependencies in the guise of a power loss on the disk friction is directly proportional to the density of the medium, in which rotation of the disk.

However, when the hydraulic machine in the turbine or pump mode when the impeller is filled with water, known technical solution is not possible when the supply of compressed air into the cavity between the impeller and cover hydraulic machines significantly reduce energy losses to the disk friction, as the proportion of the lower disk of the losses from their original values when the unit operates without compressed air, is approximately equal to the air volume in the total volume of air-to-water environment in the space between the rotating impeller and addressed to him the surfaces of the stator parts hydraulic machines. At small values of the flow rate of compressed air (up to 0.1% in a compressed state or to 1% in the conversion to atmospheric pressure the rate of flow of water) air speeds in the suction pipe, and the proportion of the gas phase will be insignificant. High consumption of compressed air, which could provide a significant component of the gas phase and thus in a noticeable decrease of loss on disk friction, resulting in reduced hydraulic efficiency and to high energy costs in obtaining the necessary volumes of compressed air, which makes the application of known solutions to the turbine or pump mode is technically and economically feasible.

Technical achiev that, to achieve the aims of the proposed technical solution is to reduce energy losses to the disk friction outer surfaces of the impeller during operation of the radial-axial hydraulic machines in the turbine or pump modes, which increases the efficiency of fluid machines.

To achieve the technical result of the proposed radial-axial hydraulic machine, which contains the shaft of the turbine with the installed impeller disk, a guiding apparatus, the suction pipe, the cover hydraulic, Foundation ring. The cover and base ring are the stator parts of a hydraulic machine. In the area around the impeller has a cavity, one of which is formed between the impeller and the cover of the hydraulic machine, and the other between the impeller and the base ring. In these cavities posted by seals, limiting leakage in the suction pipe from the space between the impeller and guide vanes. Usually in order to decrease the leakage these seals are located as close as possible to the axis of rotation of the impeller. Can be applied to different designs of seals, such as seals can be made in the form of a pair of rings, creating a narrow slit. From technological considerations, the gap between the rings vyberatelne possible.

According to the invention in each of these cavities, or only in one of them the impeller coaxially placed contactless dividing the annular hydrodynamic seal - external and internal.

Outer spacer seal is located in the area of the peripheral zone of the impeller and separates the cavity in which it is placed, from the space between the impeller and guide vanes.

Internal dividing seal is located between the outer separator seal and seal limiting leakage in the suction pipe. Internal dividing seal contains two rings: one set on the disc surface of the impeller, and the other is installed on the surface of the stator part (cap hydraulic or bottom rings), addressed to the impeller and bounding the cavity opposite to the impeller side. Each of the inner rings of the barrier seal in cross section and has a Z-shaped or angular profile. The rings are mounted so that the free shelves of their cross-sections are turned towards each other and overlap. Free shelf cross-section ring mounted on the surface of the disk impeller is further from the surface the displacement drive of the impeller, than free shelf cross-section of another ring. The shelves are arranged so that between them there is a slit gap.

Each cavity, which is equipped with internal and external separation of the seal, separated by the specified seals on two cameras - internal, enclosed separation between the inner seal and the seal limiting leakage in the suction pipe, and an outer enclosed between the outer and inner separation seals. At the same time the inner and outer chamber is connected with the space between the impeller and guide vanes, and the outer chamber provided with inlet for compressed gas.

The execution and placement of the separation of seals in each or in one of the two cavities formed between the impeller and the cover and between the impeller and the base ring, as described above, providing the separation cavity, which has the seal on two cameras - external and internal, connecting each chamber with the space between the impeller and guide vanes, and the execution of the outer chamber with the possibility of compressed gas (air) from an external source to allow for the operation of hydraulic machines in the turbine or pump mode after the compressed gas (air) in n the outer chamber to provide separation of water and air so what is the release of water from the peripheral zone of the impeller and the outer chamber is filled with compressed air, and the inner chamber is filled with water.

The proposed technical solution, maintaining the outer chamber filled with compressed gas (air) during operation of the hydraulic machine is ensured thanks to the increasing pressure from the inside (facing the axis of rotation) to the peripheral (outer) side of the slit outer and inner separation seals, resulting from the action of centrifugal forces in a rotating fluid.

The result is the release of water from the outer surfaces of the impeller during operation of the hydraulic machine in the turbine or pump modes, which allows to minimize losses on disk friction and thereby increase the efficiency of the hydraulic machine when operating in these modes.

Install barrier seals in both cavities provides the maximum reduction in losses on disk friction during operation of the hydraulic machine. Installing the separation seals due to special customer requirements can be met only in one of the cavities (or only in the cavity between the impeller and cover hydraulic machines, or only in the cavity between the impeller and the base ring), which also will reduce losses on the disk is friction, however, to a lesser extent.

The figure presents an example of performing a radial-axial hydraulic machine that includes a shaft 1 turbine installed on the shaft of the impeller 2 with the upper rim and lower rim (disks), the guide device 3, the suction pipe 4, the cover 5 of a hydraulic machine, a base ring 6.

Around the impeller has two cavities: cavity I - between the impeller 2 and the cover 5, the cavity II - between the impeller 2 and the base ring 6.

In cavities I and II are seals 7, designed to limit leakage in the suction pipe 4 from space III between the impeller 2 and the guiding device 3 during operation of the hydraulic machine. The size of the gap (slit) in the seal choose the minimum possible, thus take into account technological factors. Can be applied to seal different types, such as fricatives, labyrinth, Christmas, comb. To ensure the greatest effectiveness of the seal 7 is set at the minimum possible distance from the axis of rotation of the impeller.

In cavities I and II coaxially with the impeller 2 is installed contactless dividing the annular hydrodynamic seal - outer 8 and 9 internal, intended for the separation of water and air during operation of the hydraulic machine.

The separation seals the Oia 8, 9 can only be installed in any one of these cavities I, II. However, in this case, the reduction of losses on disk friction will be achieved to a lesser extent than in the case of installation of these seals at the same time in both cavities.

Outer spacer seal 8 is installed in the peripheral area (i.e. maximally remote from the axis of rotation of the wheel) zone of the impeller 2 and separates the cavity, in which there is separation of the seal from the space III between the impeller 2 and the guiding device 3. Presented on the figure of the radial-axial hydraulic machine outer spacer seal 8 has a design that is traditional for this type of sealing: contains two rings, one of which is installed in a peripheral zone of the disc surface of the impeller, and the other on the surface of the stator parts hydraulic machines (lid 5 or the base ring 6). Between the rings in the axial direction has a slit gap, whose value should be as minimal as possible.

Between the outer separator seal 8 and the seal 7, the bounding leak in the suction pipe, installed internal dividing seal 9, which contains the ring 10 mounted on the surface of the disc of the impeller 2, and the ring 11, is installed is on the surface of the stator parts (lid 5 or the base ring 6), facing the impeller and bounding the cavity opposite to the impeller side. The cross-section of each ring 10 or 11 internal dividing seal 9 has a Z-shaped profile.

Rings 10, 11 can also be performed with a cross-section of an angular, with each ring will be fixed on the surface of the disc or stator parts directly to the vertical cylindrical wall.

Rings 10 and 11 internal dividing seal is installed in the cavity so that the free shelves of their cross-sections are turned towards each other and overlap each other, free of the regiment of the cross-section of the ring 10 mounted on the surface of the disk impeller is further from the disk surface of the impeller than the free shelf cross-sectional return his ring 11. Between free shelves in the axial direction has a slit gap, the value of which it is reasonable to choose as low as possible.

According to the results of the analysis to be more effective release of water from the peripheral zone of the impeller is provided under the condition that the radial length of the gap-type internal dividing seal more radial extent of the gap-type outdoor time is alternova seal. To improve efficiency it is advisable to provide internal dividing seals as possible as close as possible to the axis of rotation of the impeller.

Internal dividing seal 9 divides the cavity into which it is installed, on two cameras - the inner 12 and outer 14. Inner chamber 12 is enclosed between the inner dividing seal 9 and the seal 7, the bounding leak in the suction pipe and the outer chamber 14 is enclosed between the outer 8 and 9 internal separation seals. Each of the chambers (inner 12 and outer 14) is connected with the space III between the impeller and guide vanes, respectively, with the channels 15 and 16.

Each outer chamber 14 is supplied with a supply 17 for supplying compressed gas (air), for example, through an air pipe connected to an external compressed gas (air), which after running hydraulic machines and its routines (turbine or pump) allows compressed gas (air) for the rapid release of water from the chambers 14 and subsequently maintain them filled with a compressed gas (air).

Radial-axial hydraulic machine operates as follows.

After running hydraulic machines and its steady state is work (turbine or pump) through inlets 17 is the intake of compressed gas (air) in the outer chamber 14. The pressure and flow rate of compressed air supplied to the chamber 14 through inlets 17 and the connected piping are installed in accordance with the applicable procedures so as to ensure the rapid release of water from the exterior cameras, for which the pressure must be greater than the maximum water pressure in the space between the impeller and guide vanes.

For fixation process is complete, rapid release of water from the exterior of the camera 14 can be used for automatic control, or can be pre-calculated time interval required for this process (in this case, after a calculated period of time can be considered a rapid release of water completed).

After quick release of water in chamber 14 should be provided with compressed air with low consumption. The reduction of the flow of air entering each of the outer chambers 14, and the associated reduction in pressure causes the water flowing under pressure from the space between the impeller 2 and the guiding device 3 through the channel 16 to the peripheral side of the dividing seal 8 and through the channels 15 to the peripheral side of the inner dividing seal 9, begins to penetrate the slot gap (gap) between the rings separating the seals, moving from the periphery towards the axis of rotation of the turbine. The water in the cracks separating seals 8 and 9 is driven by the forces of viscous friction on the surfaces of disks rotating rings, which, in turn, due to the centrifugal force creates a differential pressure which counteracts the movement of water in the direction of the rotation axis.

To create a stable sealing effect slotted gaps separating seals 8 and 9 should be narrow, and the amount of clearance between the rotating and stationary disks of the rings 10 and 11 shall be limited to the amount of relative movement of these disks at all possible modes of operation of the hydraulic machine.

Since the pressure in the flow of water between the impeller 2 and the guiding device 3 pulses during operation of the hydraulic machine, the boundary between water and air in the gap separating the seal is moved in the radial direction over time. For this reason, the radial length of the gap in the separation seals must be such that with a minimum consumption of compressed air division surface water were within the gaps encountered when working on the hydraulic machine, the pressure pulsation in the flow.

When known from the experience of the laboratory and on the business of testing the level of pressure pulsations in the reversible pump-turbines of the radial length of the slit inner dividing seal 9, characterized by the difference between the outer and inner radius of the slit should more radial length of the slit of the outer separator seal 8.

The consumption of compressed air supplied into the outer chamber 14 after completion of the rapid release of water, must be small to avoid the negative impact resulting in flowing air for power, efficiency and cavitation characteristics of hydraulic machines, and at the same time sufficient to maintain the outer chambers 14 free from water.

Thus, the proposed solution reduces the energy losses on the disk friction outer surfaces of the impeller during operation of the hydraulic turbine or pump modes, and hence a corresponding increase efficiency.

From the experience of hydraulic turbines and pump-turbines is known that the air flow flowing in part from reduced to atmospheric pressure with flow rates up to 0.5% of the maximum working flow of water does not adversely impact on the energy and cavitation characteristics of hydraulic machines. Moreover, the air supply with the specified flow rate has a positive impact on the operation of hydraulic machines, reducing pressure pulsations in the flow and intensity of cavitation erosion on the blades of the impeller.

Radially about the Wake of a hydraulic machine, containing the turbine shaft has mounted on the impeller disk, a guiding apparatus, the suction pipe, the cover hydraulic, Foundation ring, seal, limiting leakage in the suction pipe from the space between the impeller and guide vanes and placed in the cavities, one of which is formed between the impeller and the cover of the hydraulic machine, and the other between the impeller and the base ring, wherein at least one of these cavities coaxially with the impeller posted by dividing the annular hydrodynamic seal: inner and outer, so that the outer spacer seal separating the cavity in which it is placed, from the space between the impeller and guide vanes are located in the area of the peripheral zone of the impeller and the inner separation seal is located between the outer separator seal and seal limiting leakage in the suction pipe, the internal dividing seal contains one ring installed on the surface of the disc of the impeller, and the other ring is installed on the surface bounding the cavity opposite to the impeller side, and the cross-section of each ring inner razdelitelnikh the seal has a Z-shaped or angular profile, and the rings are mounted so that the free shelves of their cross-sections are turned towards each other and overlap each other, free shelf cross-section ring mounted on the surface of the disk impeller is further from the disk surface of the impeller than the free shelf cross-section of another ring, with each cavity, in which there is separation of the seal, separated by the specified seals on two cameras - internal, enclosed separation between the inner seal and the seal limiting leakage in the suction pipe, and an outer enclosed between the outer and inner separation seals, each camera connected to the space between the impeller and guide vanes, and the outer chamber provided with inlet for compressed gas.



 

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11 cl, 4 dwg

FIELD: machine building.

SUBSTANCE: proposed turbine comprises helical water intake case 1, mount ring 2 furnished with one row of guide vanes arranged in circle, impeller 12, straight convergent water discharge pipe 9 and lateral water discharge box 10. Said ring 2 is arranged at inner side of case 1. Ware outlet between guide vanes in ring 2 is communicated with water inlet formed between vanes 4 with curved surface. Water outlet formed between vanes 4 with curved surface is communicated with inlet of pipe 9. Outlet of said pipe is communicated with water inlet of box 10. seat 6 is arranged at impeller 12. Shaft 7 is fitted in seat 6. Blades of cooling fan are fitted directly on shaft 7. Unit designed rpm is defined by design equation and depends upon impeller water inlet diameter and water inlet pressure.

EFFECT: compact design, high efficiency and lower noise.

7 cl, 5 dwg

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