DE10302773B3 - Impeller and idler wheels for flow machines, especially compressors and fans, are made from solid matrix with flow channels in which deflection of flow and associated pressure increase take place - Google Patents

Abstract

The wheels (1,2) are made from a solid matrix with a number of flow channels (21) in which deflection of the flow and the associated pressure increase take place to reduce flow noise and to improve the characteristic stability between the inlet and outlet flow cross-sections. The solid matrix is made non-isotropically from separate segments through which the flow channels are formed.

Description

The invention relates to running and Idlers for turbomachines, especially for Compressors and fans.

The compression of gaseous fluids takes place in fans with a small pressure increase and in compressors with a big one Pressure increase.

According to the working principle of turbo compressors work by swirl change fed. It flows through the gas is a rotating impeller equipped with individual blades, through which the work is fed becomes. The flow of the Impeller is made axially, diagonally and radially. Accordingly speaks one of axial, diagonal and radial fans or compressors.

In addition to the wheels are standing, with individual Fitted with guide vanes flow guide, so-called idlers to improve job transfer and the efficiency used in fans and compressors. The blades of the impellers and idlers have an entry or leading edge and a trailing or trailing edge.

The surfaces of the blades between the front and trailing edge are referred to as pressure side and suction side.

With respect to the blades of the barrel and idlers the mean pressure on the pressure side of the blades is greater than on the suction side, creating forces act on the blades.

These forces are equal to the forces which the blades and guide vanes exert on the flow and those for changing the swirl and job transfer in the fans and compressors. The blades are after executions according to the status the technology on a hub with axial, diagonal or radial Contour attached.

On the outer, opposite the impeller hub Side can the blades over one Ring, the shroud, connected and attached. With diagonal and centrifugal fans and compressors, this ring becomes a cover plate called.

The idlers and the impellers are outward towards a housing enclosed. The stator hub can be upstream and downstream by a fixed casing be continued. The column between the impeller or stator and housing in the interest of small flow losses, preferably executed small. The drive of the wheels is usually done by an electric motor via the impeller hub.

When rotating the wheels and the pressure fields bound to the blades between pressure and As is known, the suction side is created an intense sound, which is also called rotary sound.

Another important source of the Noises are the pressure fluctuations that occur when the air flows through the Impellers and idlers and the associated formation of large and small vortices.

To minimize the resulting Many measures are known in the prior art for sound.

A distinction is made between active measures, such as the design of fans and compressors with small flow losses, the choice of uneven spacing of the blades from one another (division) and, for example, according to the DE 196 04 638 A1 , the sickling of the blades or by rotating nozzles and diffusers.

Also known after the DE 42 05 925 A1 is a blower in which the middle part of the blades is made of porous material. The porous material enables flow through the blades from the pressure to the suction side. This results in a reduction in the pressure differences and a reduction in the noises that occur as a result of eddies and the pressure differences. However, this also reduces the efficiency of the work transfer and the pressure increase.

According to the teaching of US 005244349 To reduce the mass, blades with perforation are used instead of the porous material.

The situation is similar for an axial wheel with sickled blades which are interrupted in the direction of flow according to the teaching of DE 196 04 638 A1 , This results in an improved pressure distribution and an improved work transmission as well as a reduced noise.

Likewise, in the state mentioned the technology reports that by protrusions on the rear edges of impellers a reduced noise emission is achievable. It is assumed that the projections both act on the pressure fields as well as on the eddies in the flow.

The second group of measures essentially aims at damping the noises created from. This group is also known as passive measures.

For example, after the DE 100 19 237 A1 proposed to run the hub and the housing from sound-absorbing material.

After DE 42 44 906 C2 describes a blower in which a part of the inner housing is formed by sound-absorbing material.

In the DE 196 04 638 A1 In fans, a sickling of the blades is proposed to reduce noise.

Further approaches to solving the noise problem with impellers and idlers can be found in the CH-PS 409 225 , where a fiber body with elongated fiber-shaped individual bodies is provided as the flow grating.

According to the teaching of DE-PS 174 180 zigzag-shaped rings and bands are used, which are traversed across the waves.

In the GB 2 065 773 A rigid porous materials are used as disks for the transfer of work in order to provide stable impellers.

The company is devoted to a similar aspect, that of the inexpensive manufacture of wheels DE 195 45 977 A1 , where usual paddle wheels are replaced by inexpensive simple curved sheet metal strips.

To assess the sound power level of Fans use the specific, A-weighted sound power level, the agreed upon values of total pressure increase, volume flow and speed is related. Arrange these specific sound power levels for example the number of diameters as a key figure for the design of the fans too, there is a band in which the efficiency and specific sound power level of good fans. Very good centrifugal fans achieve specific overall sound power levels of about 20 dB (A), axial fans 32 dB (A).

However, the development of the past years showed that despite intensive efforts it did not possible was to further reduce the minimum specific sound power levels. The state of the art therefore remains liable despite intensive efforts the downside to the noise level of fans and compressors is still unacceptably high.

Fluidically favorable fans and Compressor with large pressure increase and big Have volume flow at a given speed and diameter frequently no stable characteristic. The characteristic curve, determined by plotting the pressure increase dependent on of the volume flow falls not monotonous with increasing volume flow.

This property is caused by uneven tear signs on the rotor blades or guide vanes - rotating tearing off - and leads to Drop in efficiency, increased sound radiation and additional mechanical load on the blades. Therefore fans must not be in an unstable state Operating area. To prevent the unstable Various stabilization devices are known in operation.

The invention is therefore the object based on impellers and idlers for axial, to develop diagonal and radial fans or compressors that a significantly smaller specific sound power level than conventional Have fans or compressors.

It continues to be an improvement the stability of the characteristic sought. According to the task through impellers and idlers for turbomachines, especially for Compressors and fans released, which to reduce flow noise and to improve the stability of the characteristic between the on and the Outlet cross section for the flow are formed from a solid matrix with a large number of flow channels, in which a redirection of the flow and the associated pressure increase he follows.

According to an advantageous embodiment According to the invention, the solid matrix is not isotropic with respect to one another spaced segments built through which the flow channels for the fluid be formed.

The segments point in the direction of flow, for example polygonal cross sections and are formed from ribbons.

They are also advantageous Segments with a honeycomb, square or trapezoidal cross-section educated.

The segments are preferred through ribbons made of plastic or metal or in a casting process manufactured.

After another advantageous one Embodiment of the invention, the solid matrix consists of isotropic porous Materials which flow channels for the fluid exhibit.

Foams are advantageously used as porous materials, metal or plastic foams are particularly suitable.

After another advantageous one Embodiment of the invention is the solid matrix of fibrous Structures or also arranged transversely to the direction of flow Seven formed.

The success according to the invention is also achieved if the solid matrix is in the flow direction is built up at least two layers, the first layer from fibrous structures or from isotropic porous material accomplished and the second layer is formed from segments.

It is generally advantageous to mechanical stabilization of the solid matrix covering tapes or also with a radial design of the impellers a support disk and one Form cover plate.

One in terms of minimization the flow noise especially advantageous embodiment of the invention is that the flow channels to enable partial pressure equalization in the radial or circumferential direction and the associated reduction in noise pollution in part are connected.

After conceiving the invention become the impellers and idlers just not as usual with individual blades. According to the teaching of the invention the impellers and idlers through a solid matrix formed with a variety of flow channels.

Structured are under a solid matrix Materials with flow channels for the fluid to understand where the flow is redirected.

In the training as an axial fan, the solid matrix of the impeller or stator is an example wise disc-shaped.

The solutions according to the invention have the following Advantages described:

• - The labor transfer as with turbo machines a twist change. Instead of the polar of the wing, of lattice influences and the edge losses occur new parameters. That is primarily the forces (3 components) per unit volume by the solid matrix or the structured materials are exerted on the flow.
• - The with known solutions to the individual rotor blades and guide vanes as well as webs and the like bound vortex noise as well as the rotating sound and the siren sound are eliminated. Therefore points the sound spectrum in the middle frequency range that determines the fan noise extremely low levels. The flow noise at very high frequencies increases. However, this does not have a significant effect on the A-weighted level out.
• - In the Partial load range usually arises with highly loaded fans Tear off "and In connection intense sound. Rotary tearing is based on laminar detachment and the formation of large, over individual Buckets of a wheel going beyond structures. Such effects occur with a solid matrix made of structured material, i.e. all characteristics are stable, no extra stabilizers.
• - The Efficiencies of the new fans are not essential worse than that of conventional ones Fans, the losses of which consist of flat, edge, gap and Compound mix losses. For blades made of structured material are the losses for generating the redirection (analogous to the levels Losses) much larger than usual. Edge losses, gap losses and mixture losses decrease.
• - All Struts, e.g. to mount the motor, will be beneficial either made of structured material or they will be in this integrated, so that the size of the separation vortex is minimized.
• - To the Achieving good part-load behavior can be two or more different Basic structures are used in the impellers and idlers. So is an isotropic fibrous structure at the wheel entrance to minimize the shock losses and a honeycomb structure at the wheel outlet to reduce friction losses particularly advantageous.
• - For a variety of applications with axial conveying direction step pressure numbers of about 1 are required (e.g. vacuum cleaner fan). This is so far only with radial stages, often with downstream guide and return grids, possible. Axial fans with correspondingly high pressure numbers have unstable Characteristic curves with all the resulting disadvantages. With axial steps off Structured materials do not suffer from this disadvantage.

The impellers and guide wheels according to the invention are because of their characteristic stability used in particular in smoke extract fans.

The concept of the invention is also because the lower noise level for Computer fans used. As another example of use is use of the concept for To name steam turbo compressors.

The aforementioned selection of possible uses shows that the solution principle according to the invention on a large number of differently dimensioned fans and compressor can be used.

More details, features and Advantages of the invention result from the following description of embodiments with reference to the related Drawings. Show it:

1 : Axial section of an axial fan for pipe installation,

2a . b : axial view of the axial fan for pipe installation (detail),

3 : developed coaxial cut through the impeller and stator of the axial fan for pipe installation,

4 : Axial section through an axial fan with free suction,

5 : developed coaxial section through the impeller and stator of an axial fan made of fibrous and cellular material,

6 : Axial section through a radial fan with a running edge made of finely structured material,

7 : different cellular structures for a radial fan impeller (radial section),

8th : developed coaxial section through the impeller and stator of a radial fan, in which the cellular structure is formed by many corrugated and profiled disks,

9 : developed coaxial section through the impeller and stator of a radial fan, in which the cellular structure is formed by many ribbed disks,

10 : developed coaxial section through the impeller and stator of a radial fan, in which the cellular structure is formed by many ribbed disks,

11 : axial view of the ribbed washers according to 10 .

11a . b developed coaxial section through an impeller or stator of the axial fan with tabs,

12 Radial section structure for a radial fan impeller with tabs.

1 shows an axial fan 23 with impeller 1 , Idler 2 and impeller hub 3 for fastening the impeller 1 on the shaft of the drive motor 5 . which is usually designed as an electric motor. In addition to their function of deflecting the flow in a suitable manner, the guide vanes have the task of driving the motor 5 in the housing 6 to keep. For reasons of strength and assembly, the guide wheel 2 inside by a stator hub 4 limited. The shaft of the drive motor is designated 22.

According to the invention, impellers and idlers made from a solid matrix of preferably finely structured material are used instead of the usual impellers and idlers with profiled twisted individual blades. The wall thicknesses of the materials forming the segments can be chosen to be very small. The force effect of the blades on the flow in conventional fans is divided into many small segments or "structural elements" of the matrix. The structure results in a very high strength of the impeller and stator 1 . 2 , For special requirements, the impellers and idlers 1 . 2 Integrated support elements, not shown.

The segments point in the direction of flow 11 polygonal cross sections, honeycomb cross sections 15 or square or trapezoidal cross-sections.

The segments are marked by ribbons 19 made of plastic or metal. All struts, webs, holding devices etc. should also consist of structured material or be integrated into this. The direction of the inflow is also shown 11 of the fluid and the axis of rotation 10 the motor shaft of the drive motor 5 and the impeller 1 ,

According to a preferred alternative embodiment of the invention, the impellers and guide wheels 1 . 2 designed to reduce running or flow noise from isotropic foams.

The isotropic foams are advantageous as Made of metal or plastic foam.

The design of the impellers and guide wheels is also advantageous 1 . 2 from fibrous structures 14 ,

In 2 is a detail of the view of the axial fan in the flow direction 11 shown enlarged. The structure of the segments is created, for example, by winding and connecting a tape 19 with prefabricated bars 20 , The division of the structure is usually greater in the radial direction than in the circumferential direction in the case of a strong swirl change for reasons of reducing the twist, because the losses of the secondary flow increase with the deflection and with the aspect ratio of the cells in the radial direction and in the circumferential direction. It can have passage openings in the radial and in the circumferential direction, which is used for speed and pressure compensation in the radial and circumferential directions.

3 arises from a coaxial cut and its processing in one plane. You can see the flow channels 21 that are for impeller and idler 1 . 2 differ. The inflow direction is to illustrate the cutting geometry 11 and the direction of rotation 12 of the impeller 1 specified. The flow channels 21 can, as shown, be continuous or consist of several sections. The dimensions of the flow channels 2 should be chosen so that laminar boundary layers occur at Reynolds numbers just below the change to turbulent boundary layers.

4 shows an axial fan with suction nozzle. To achieve good part-load behavior, two different layers of structures are in the impeller according to this advantageous embodiment of the invention 1 applied. The same is the case with the diffuser 2 possible. The upstream 11 first layer has a fibrous isotropic structure 14 to minimize shock losses at the wheel entry. The subsequent second layer at the wheel outlet is made of a honeycomb structure 15 formed and is advantageous for reducing friction losses.

In addition, the fibrous isotropic structure enables 14 radial flow compensation. The centrifugal and centripedal channel guidance in the structures of the impeller and guide wheel 1 . 2 can advantageously be used to achieve a desired radial pressure and speed distribution. The suction nozzle 13 has with regard to the finely structured impeller 1 a very small radius of curvature. To ensure the strength of the impeller 1 becomes a shroud 7 used, which also holds the different layers together.

5 shows in a developed coaxial section analog to 3 the fibrous isotropic structure 14 at the impeller and stator entry and the honeycomb structure 15 at the outlet of the impeller and diffuser 1 . 2 ,

In 6 is an axial section through a radial fan 24 with an impeller according to the invention 1 made of finely structured material. The impeller 1 made of finely structured honeycomb material is over the supporting disc 16 and the impeller hub 3 with the drive motor 5 connected. The cover plate 8th limits the impeller to that of the supporting disc 16 opposite side. The impeller is from the volute 9 enclosed. In various applications it is advantageous to go behind the radial impeller 1 a stator not shown 2 , which is also made of finely structured material.

The impeller 1 depending on the task with different fibrous 14 or different honeycomb-like, cellular structures 15 built up. 7 shows in the 4 quadrants a radial section through the impeller 1 of a radial fan, various combinations and structures which are formed from one or more straight or curved honeycomb-like structures and from combined bevel and honeycomb-like structures. In general, the subdivision of the impeller in the axial direction and circumferential direction creates the desired fine Structure.

According to the first quadrant 7a) a two-layer impeller is shown. It consists of a first layer with a fibrous structure 14 and a second layer with a honeycomb structure 15 ,

According to the second quadrant 7b) Two layers are shown, the first layer having a honeycomb structure in the radial flow direction 15 with obliquely arranged segments and then a second layer consists of a honeycomb structure with radially arranged segments.

According to the fourth quadrant 7c) is shown a layer made of a honeycomb structure 15 with slanted segments. According to the third quadrant 7d) again a layer is shown, which consists of a honeycomb structure 15 exist with curved segments.

In 8th and 9 is the formation of a finely structured radial impeller from many thin, profiled and prefabricated disks 17 with ribs after 7 shown. These disks are placed axially next to each other and connected together. This creates a radial impeller 1 with high strength, which can be improved by additional tie rods in the axial direction.

10 shows a developed coaxial section through impeller or idler 1 . 2 a centrifugal fan 24 , in which the cellular structure is covered by many ribbed disks 17 is formed. The cellular structure is limited by the supporting disk 16 , According to this advantageous embodiment of the invention, the arrangement of the segments shown leads to mechanical stabilization, since the forces in the circumferential direction can be better absorbed by the segments arranged in this way.

11a and 11b show the coaxial section and the axial section of an axial impeller or stator in which the flow channels 21 by tabs 26 formed by punching and bending from strips. Seals are used to reduce radial flow compensation 25 used.

12 shows a disc, the ribs of two rows of tabs 26 are formed with different inclinations to the circumferential direction. The use of more than two rows of tabs 26 is an advantageous embodiment of the invention.

1

Wheel

2

stator

3

impeller hub

4

stator hub

5

drive motor

6

casing

7

shroud

8th

cover disc

9

volute

10

axis of rotation

11

inflow

12

direction of rotation of the impeller

13

suction

14

fibrous structure

15

honeycombed structure

16

carrying disc

17

profiled disc

18

Koaxialschnitt

19

tape

20

Stege

21

flow channel

22

wave of the drive motor

23

Axial

24

centrifugal fan

25

seal

26

flap

Claims (14)

Impeller and stator for a turbomachine, in particular for compressors and fans, the impeller and stator ( 1 . 2 ) from a solid matrix with a large number of flow channels ( 21 ) and that the solid matrix is not isotropically made up of spaced segments through which the flow channels ( 21 ) for the fluid and that the impeller and stator ( 1 . 2 ) also acts as a rectifier or sieve. Impeller and diffuser according to claim 1, characterized in that the segments in the flow direction ( 11 ) have polygonal cross sections and from strips ( 19 ) are formed. Impeller and diffuser according to claim 2, characterized in that the segments in the direction of flow ( 11 ) honeycomb-like cross sections ( 15 ) exhibit. Impeller and diffuser according to claim 2, characterized in that the segments have square or trapezoidal cross sections. Impeller and diffuser according to one of claims 1 to 4, characterized in that the segments are formed by bands ( 19 ) are made of plastic or metal. Impeller and stator for a turbomachine, in particular for compressors and fans, the impeller and stator ( 1 . 2 ) from a solid matrix with a large number of flow channels ( 21 ) and that the solid matrix consists of isotropic porous materials, which flow channels ( 21 ) for the fluid and that the impeller and stator ( 1 . 2 ) also acts as a rectifier or sieve. Impeller and diffuser according to claim 6, characterized in that as porous Materials foams be used. Impeller and diffuser according to claim 7, characterized in that the isotropic foams as metal or plastic foams accomplished are. Impeller and stator for a turbomachine, in particular for compressors and fans, the impeller and stator ( 1 . 2 ) from a solid matrix with a large number of flow channels ( 21 ) and that the solid matrix consists of fibrous structures ( 14 ) which flow channels ( 21 ) for the fluid and that the impeller and stator ( 1 . 2 ) also acts as a rectifier or sieve. Impeller and stator for a turbomachine, in particular for compressors and fans, the impeller and stator ( 1 . 2 ) from a solid matrix with a large number of flow channels ( 21 ) and that the solid matrix consists of transverse to the flow direction ( 11 ) arranged sieves is formed and that the impeller and idler ( 1 . 2 ) also acts as a rectifier or sieve. Impeller and stator for a turbomachine, in particular for compressors and fans, the impeller and stator ( 1 . 2 ) from a solid matrix with a large number of flow channels ( 21 ) exists and that the solid matrix in the direction of flow ( 11 ) is made up of at least two layers, the first layer consisting of fibrous structures ( 14 ) or is made of isotropic porous material and the second layer is formed from segments. Impeller and guide wheel according to one of claims 1 to 11, characterized in that for the mechanical stabilization of the solid matrix cover bands ( 7 ) are provided. Impeller for a turbomachine according to one of claims 1 to 12, characterized in that for the mechanical stabilization of the solid matrix in the radial design of the impeller, a support disc ( 16 ) and a cover plate ( 8th ) are provided. Impeller and diffuser according to one of claims 1 to 13, characterized in that the flow channels ( 21 ) are partially connected to each other in the radial direction.