EP2681454B1 - Resonator silencer for a radial flow machine, in particular for a radial compressor - Google Patents

Description

The invention relates to a diffuser for a radial compressor, which diffuser has a substantially annular cavity, which is delimited at least by a first radial side surface.

Radial compressors are known, for example from the EP 1 356 168 B1 or the EP 1 602 810 A1 ,

The in the EP 1 602 810 A1 . DE 603 10 663 T2 . DE 601 20769 T2 and US 2009/229280 A1 Diffusers shown have a circumferential groove, which is filled or covered with a material and so does not form a resonator.

The DE 601 14 484 T2 shows an empty circumferential groove in the diffuser.

Such radial compressors consist of a compressor stage forming, rotating about a rotation axis impeller with a - with respect to the axis of rotation of the impeller - axial inlet and a radial outlet. Gas to be compressed flows axially into the impeller of the compressor stage and is then deflected outwards (radial, radial seal), leaving the impeller at high speed.

Kinetic energy of the high-velocity gas to be compressed is then converted into potential energy in the form of pressure in a diffuser.

Such a diffuser is usually formed by two non-rotating, an annular cavity or an annular space forming rings, which annular space radially adjoins the impeller outlet and which rings or annular walls / side surface radially adjoin the impeller outlet Sense and perpendicular to the axis of rotation or to this at a very obtuse angle (radial annular space walls / radial side surfaces).

The gas exiting the impeller is guided radially outward in this annular space between these two annular walls and reaches a collector.

Often, diffusers have wings, d. H. a blading, for steering and better control of the slowing down of the flow.

Furthermore, it is known that such radial compressors cause relatively high sound emissions or noise levels, which represent a (noise) impairment of an environment of the centrifugal compressor. In addition, these sound emissions can trigger vibrations and structure-related malfunctions.

For example, dominant sound sources in a centrifugal compressor are typically generated at the impeller and diffuser inlet or diffuser vanes due to the high velocity of the fluids flowing through these regions, as well as the interaction of rotor and stator components.

In particular, it is known here that radial compressors produce at an outlet from the radial compressor (pressure side), for example at local pressure nozzles, complex, unsteady, three-dimensional, rotating and / or pulsating pressure fields or sound fields whose sound waves are undisturbed in the pipes connecting to the pressure nozzles spread.

This can - in addition to the mentioned noise, vibration and structural dysfunctions - also come to pipe vibrations, which can lead to damage to the pipes to failure of the centrifugal compressor or the parent, the centrifugal compressor having system.

The attenuation of such complex, unsteady, three-dimensional, rotating and / or pulsating pressure fields or sound fields is technically difficult.

On the basis of this, efficient soundproofing measures are necessary for such sound-emitting radial compressors.

Various sound emission limiting, "external" measures, such as housings or enclosures are known. These noise reduction techniques can be relatively expensive, especially if offered as a "later" add-on product.

Furthermore, "internal" mufflers for limiting noise emissions in radial compressors are known.

Mufflers in general are devices for reducing noise emissions. Different types of silencers are distinguished, which reduce a generated sound power due to different mechanisms of action. For example, a distinction is made between absorption and reflection / resonator silencers.

An absorption silencer, as for example from the EP 1 602 810 A1 is known for a radial compressor, contains porous (absorption) material, usually rock wool, glass wool or glass fiber, which partially absorbs sound energy, ie, converts into heat. Absorption in the muffler mainly dampens upper frequencies of the sound medium.

Such backfills of a corresponding cavity are also in the DE 603 10 663 T2 . DE601 20769 T2 and US 2009/229280 A1 proposed.
The DE 601 14 484 T2 discloses a circumferential groove whose depth is increased to more than 1.5 times the axial width of the recessed portion of the compressor wheel.

Absorption mufflers have the disadvantage that they are usually unsuitable for high pressures, since - connected to the high pressures - high energy inputs act on the absorbent material or high heat inputs are absorbed by the absorbent material, resulting in damage to the porous material, as can lead to a dissolution of the absorbent material.

Resonator silencers or reflection silencers, which use the principle of sound reflection, usually contain a plurality of cavities or chambers, past which the sound medium passes, which leads to reflections. The multiple passages through the chambers of the chambers through the sound medium leads to a reduction of sound pressure peaks of different frequencies. These reflections are - constructively - generated by baffles, cross-sectional widening and narrowing. By reflection, any frequencies of the sound medium can be damped in the muffler.

Such a resonator muffler, based on a Helmholtz resonator principle, for a centrifugal compressor is known from EP 1 356 168 B1 or from the EP 1 443 217 A2 known. In this centrifugal compressor, the local diffuser has an acoustic lining in the form of a field with numerous holes, which act as Helmholtz resonators on.

In addition to such a radial compressor is known as a further form of a radial flow machine, a radial turbine.

Such a radial turbine, such as from the DE 44 38 611 C1 is known, based on a reversal of the physical principle of a centrifugal compressor and is accordingly - in the same components - as in a radial compressor - flows in the reverse flow direction as in this.

Even with radial turbines, the emission problems described occur in a corresponding manner.

For example, dominant sound sources in a radial turbine typically at the location of the impeller or a turbine wheel (both also referred to below as impeller) and a Turbinenleitkranzes upstream of the turbine or any Leitschranzschaufeln generated.

Again, on a suction side, d. H. Complex, unsteady, three-dimensional, rotating and / or pulsating pressure fields or sound fields are generated at an entrance to the radial turbine, for example at a local suction nozzle, the sound waves propagate undisturbed in upstream of the suction pipe.

Based on this, efficient soundproofing measures for such sound-emitting radial turbines are also necessary here.

It is the object of the invention to provide a silencer, which improves the disadvantages of the prior art, easy to implement and also easy - in a sound-emitting system or device, such as a radial flow machine, - is installed and which in particular for a Damping of sound emissions in a centrifugal compressor or a radial turbine is suitable.

The object is achieved by a diffuser for a radial flow machine, in particular a centrifugal compressor, with the features according to the independent claim.

This diffuser has a substantially annular cavity, an annular space, which is bounded at least by a first radial side surface. According to the invention, at least one substantially annular circumferential groove is formed in this side surface.

This at least one substantially annular circumferential, groove open to the annular space (Nutausgangsöffnung) groove acts as an acoustic resonator, in particular lambda / 4 - resonator - shortly hereinafter also only resonator - so that the groove passing sound waves, the same Have frequency as an (acoustic) Eigen- or Resonant frequency of this groove, reflected in a region of Nutausgangs and thus a sound propagation across the groove or the resonator away are reduced.

As a result, the sound propagation in the annular space can be reduced and an effective sound attenuation in the diffuser - and the radial flow machine or the radial compressor - can be achieved.

By a selected geometry or dimensioning of the substantially annular circumferential groove, in particular by a depth of the groove, by a width / height of the groove or the Nutausgangs, by a radial position of the groove in the radial side surface, eigenform (eigenmode) or Knot diameter and natural or resonance frequency of the groove determined.

The configuration or the (three-dimensional) geometry of the circumferential groove - in itself - are so far no limits, as formed by the circumferential groove, a cavity or a cavity, which acts as an acoustic resonator.

Thus, for example, circumferential grooves with any groove shapes, such as circumferential grooves with a rectangular, V-shaped or trapezoidal cross-section, circumferential grooves with outwardly slanted wall and / or circumferential grooves as dovetail and / or circumferential grooves with - have area or completely - smooth and / or curved walls and / or circumferential grooves with undercuts and / or be realized with chambers. Wavy circumferential grooves or circumferential grooves with a stepped groove bottom are also possible.

If a sound wave passing by the groove thus has the same eigenform or a same nodule diameter as a same acoustic eigenform in the resonator or the groove on and / or has the groove passing the groove sound wave at the same natural frequency as that of the groove, the reflection is particularly effective.

D. h., By suitable (three-dimensional) dimensioning of the groove, the natural acoustic frequency and the natural shape of the groove on a sound wave to be reflected, d. H. be tuned to their frequency and eigenform, and thus targeted frequencies - are attenuated by the dimensioning of the groove.

In other words, due to the three-dimensionality of the substantially annular circumferential groove (even circumferential groove) whose eigen forms can be adjusted via simple geometric parameters so that the groove passing acoustic pressure pattern with a particular shape are reflected particularly effective.

The shape of these passing acoustic pressure patterns can be estimated, for example, via analytical correlations, such as according to a formula according to Tyler & Sofrin.

The geometry of a circumferential groove is easy to manufacture and, due to the smaller number of free parameters such as height, width, depth, or shape, offers the possibility of integration into an optimization process.

Furthermore, the invention achieves a robust maintenance-free (sound damping) solution that is not subject to wear even at high pressures and temperatures. It offers a distinct advantage over absorption material based approaches.

Since the "muffler" according to the invention near the sound source (impeller and possibly bladed diffuser / possibly bladed Leitkranz) is used, with proper dimensioning Also, the excitation of the impeller can be reduced by acoustic pressure pattern.

When using the circumferential groove in the annulus no further soundproofing measures, especially in the piping system, are required. Both a noise emission, as well as the excitation of pipe vibrations can be significantly reduced. This results in a significant cost advantage over external silencer solutions.

Expected pressure drops are low, as shown by both numerical calculations and experiments.

Preferred developments of the invention will become apparent from the dependent claims.

In a preferred embodiment, the at least one first radial side surface has a plurality of essentially annular, in particular concentric, grooves lying on one another. Through several such circumferential grooves, the efficiency of the muffler can be increased.

These circumferential grooves can be particularly preferably designed such that they each have different dimensions, in particular different depth and / or width. For example, it may be provided here that with a growing radial distance in the annular cavity or annular space to the outside, the depth and the width of the circumferential grooves are each smaller.

In this way, ie by a plurality of circumferential grooves, it is possible to specifically attenuate a plurality of frequencies up to a broadband sound attenuation of sound emissions in the radial flow machine. For example, a frequency band to be damped of 700 Hertz - 2000 Hertz, 700 Hertz - 4000 Hertz or 700 Hertz - 6000 Hertz can be realized.

The efficiency of the "resonator muffler" can be further increased if the annular cavity is delimited by one of the first radial side surface axially opposite, second radial side surface, which second radial side surface also a substantially annular circumferential groove or - with further increase in efficiency - more having substantially annular circumferential, in particular concentric with each other, grooves.

On this basis, it can be provided according to a further preferred development that the one substantially annular circumferential groove of the first radial side surface of a substantially annular circumferential groove of the second radial side surface directly, d. H. at the same radial height, axially opposite.

Alternatively, however, it may also be provided that the one substantially annular circumferential groove of the first radial side surface of a substantially annular circumferential groove of the second radial side surface radially offset, d. H. with different radial height, opposite. This may be particularly advantageous if, due to arranged in the annular cavity or annulus elements, such as a blading, a place for a "directly axially opposite arrangement" of the circumferential grooves is not available.

Such a directly axially opposing arrangement as well as a radially offset arrangement of circumferential grooves can also be provided in each case with a plurality of essentially annular, concentric grooves in the two radial side surfaces. Again, the space conditions in the annulus (bladed annulus) may be crucial to provide instead of a "directly axially opposite arrangement" radially offset circumferential grooves.

In a further preferred embodiment, the natural frequency of the at least one substantially annular circumferential groove is tuned to a frequency to be reflected. More preferably, the frequency to be reflected may be a blade passing frequency of a radial compressor or a second harmonic or third harmonic or fourth harmonic to the impeller revolution frequency of the centrifugal compressor. Preferably, the eigenform of the at least one substantially annular circumferential groove is tuned to the natural shape of a sound wave to be reflected.

In a further preferred embodiment, the substantially annular cavity has a blading.

This may result in that the at least one substantially annular circumferential groove or a plurality of such circumferential grooves is or are arranged in an area of the blading in the annular space.

It can also be provided that the at least one substantially annular circumferential groove or a plurality of such circumferential grooves is arranged outside the region of the Beschauflung in annular space or are.

It can also be provided that the at least one substantially annular circumferential groove has interruptions. This can be provided, for example, when the annular space has a blading, which prevents a completely circumferential groove.

According to a further preferred embodiment, it is provided that the "(resonator) silencer" - as a local diffuser - is used or realized in a radial compressor. Also, the "silencer" can be used in a radial turbine at a turbine runner upstream of a turbine runner of the radial turbine or implemented there.

It can also be provided that - in the case of a plurality of substantially annular circumferential grooves - these are designed such that a damping for a large speed range of z. B. 50% to 105% of a rated speed of the radial flow machine or the radial compressor are designed.

In figures, embodiments of the invention are shown, which are explained in more detail below.

FIG 1

Skizze einer Schnittdarstellung einer radialen Strömungsmaschine, eines Radialverdichters, mit einem Resonatorschalldämpfer gemäß einer Ausführungsform;

FIG 2

Skizze einer Schnittdarstellung einer radialen Strömungsmaschine, eines Radialverdichters, mit einem Resonatorschalldämpfer gemäß einer weiteren Ausführungsform;

FIG 3

Skizze einer Schnittdarstellung einer radialen Strömungsmaschine, eines Radialverdichters, mit einem Resonatorschalldämpfer gemäß einer weiteren Ausführungsform;

FIG 4

exemplarisch einen akustischen Eigenmode in einer Ringnut bei einem Radialverdichter gemäß einer Ausführungsform.

Show it

FIG. 1

Sketch of a sectional view of a radial flow machine, a radial compressor, with a resonator silencer according to an embodiment;

FIG. 2

Sketch of a sectional view of a radial flow machine, a radial compressor, with a Resonatorschalldämpfer according to another embodiment;

FIG. 3

Sketch of a sectional view of a radial flow machine, a radial compressor, with a Resonatorschalldämpfer according to another embodiment;

FIG. 4

exemplarily an acoustic eigenmode in an annular groove in a radial compressor according to one embodiment.

Exemplary embodiments: Resonator silencer for radial compressors

FIGS. 1 to 3 show various embodiments of centrifugal compressors 100, each with a resonator muffler 1 realized or integrated in the diffuser.

Such radial compressors 100 as shown have an impeller 10 which rotates about an axis 11 at high speed. The impeller 10 has a hub 12 and radially projecting blades 13th

The hub 12 has a first region 12a that is substantially cylindrical, a transition region 12b in which the hub radius widens, and an end region 12c that is substantially perpendicular to the axis 11.

The - with flow direction 3 - axially flowing gas 2 is rotated by the impeller 10 in rotation and leaves the impeller 10 in the radial flow direction 3 to the axis 11 and at an obtuse angle to the axis eleventh

The blades 13 are attached to a common back plate 14 of the hub 12. The impeller 10 is located in a housing 15 whose wall 16 is adapted to the outer contour of the impeller. The fan formed by the impeller 10 has an axial inlet 17 and a radial outlet 18 extending around the circumference of the impeller 10.

At the outlet 18, the diffuser 20 connects, which is fixedly connected to the housing 15 and does not rotate. The diffuser 20 has a substantially radial support wall 21, to which vanes 22 (diffuser blades) are attached, which guide the flow passing through the outlet 18.

The radial support wall of the diffuser 20 axially spaced opposite is another substantially radial wall 23, whereby the diffuser 20 forms an annular space occupied by the blading 22, the annular space 30.

The wings 22 extend substantially radially to the axis 11. Between the wings 22 diffuser channels are formed, the cross-sectional area increases from the inside to the outside.

The purpose of the diffuser 20 is to slow down the accelerated by the impeller 10 gas, which has a high kinetic energy and convert the kinetic energy in pressure.

At an outlet 26 of the diffuser 20 is connected - further downstream - a (not shown in detail) piping system 29 (pressure side 27), which is connected via a pressure port 28 to the diffuser 20.

Such centrifugal compressors 100 as shown cause high levels of noise emissions that can (noise) affect an environment of the centrifugal compressor 100, vibration, structure-related malfunction, as well as pipe vibrations in / on piping systems can cause which pipe vibrations to damage to the pipes to failure of the Run radial compressor 100.

Dominant sound sources of such emissions are generated at the location of the impeller 10 and the diffuser inlet 25 or any diffuser vanes 22 due to the high velocity of the fluids flowing through these regions.

Complex, unsteady, three-dimensional, rotating and / or pulsating pressure fields or sound fields are generated in particular on the pressure side 27 or at the pressure outlet 28 of the radial compressor 100, whose sound waves propagate undisturbed into the pipes 29 adjoining the pressure connection 28 and are described there Damage may cause.

To avoid such damage or as effective soundproofing, the radial compressors 100 - as shown in FIGS. 1 to 3 - each provide a resonator muffler 1 realized or integrated in the diffuser or in the annular space 30 there.

To reduce the propagation of the sound waves in the annular space 30 of the diffuser 20, as shown in FIGS. 1 to 3, one or more circumferential annular grooves 50 extending annularly about the axis 11 in the radial support wall 21 and / or in the radial Wall 23 attached, which act as acoustic resonators, in particular as lambda / 4 - resonators.

In this case, these - annular and concentric with the axis 11 extending - circumferential grooves 50 both on one side in the annular space 30, for example on the radial support wall 21 or on the radial wall 23, as well as on both sides, d. H. be attached to both the radial support wall 21 and on the radial wall 23.

These circumferential grooves 50 may also be arranged only in the region of the blading 22 of the diffuser or only in the region outside the blading 22 of the diffuser 20 and also in and outside the region of the blading 22 of the diffuser 20.

Through the annular space 30 or at the circumferential / annular grooves 50 passing sound waves having the same frequency as one of the resonance frequencies of such a circumferential / annular groove 50 are in the region of the resonator 51, d. H. the slot opening or the Nuteingangs 51, reflected and thus damped.

FIG. 1 shows an embodiment of this resonator muffler 1, which has two each concentric to the axis 11 annular circumferential grooves 50.

One of the two circumferential grooves 50 is arranged on the radial support wall 21. Approximately at the same radial distance from the axis 11, the second of the two circumferential grooves in the radial wall 23 is arranged. Both circumferential grooves 50, which are identical in shape, width and depth and have a U-shaped cross-section, are therefore directly, d. H. at the same radial height, axially opposite.

Their radial distance from the axis 11 or its radial position in the annular space 30 is dimensioned such that both circumferential grooves 50 (radially) outside the bladed region 22 of the diffuser 20 and annulus 30 lie.

FIG. 2 shows a further embodiment of a resonator muffler 1 in the diffuser 20, which has a plurality each concentric with the axis 11 annular circumferential grooves 50.

A first part of these circumferential grooves 50, here four circumferential grooves 50, is arranged on the radial support wall 21 in the region of the blading 22 of the diffuser 20. These circumferential grooves 50 directly axially, d. H. each at the same radial height or in each case the same radial distance from the axis 11, opposite a second part of the circumferential grooves 50, also four circumferential grooves 50, on the radial wall 23 - thus also in the bladed region 22 of the diffuser 20 and annulus 30 - arranged.

Mutually immediately opposite circumferential grooves 50 are identical in each case in shape, width and depth. In this case, the width and the depth of the circumferential grooves 50 decrease with increasing distance from the axis 11. In other words, as the radial distance from the axis 11 increases, the circumferential grooves 50 become narrower and less deep. All circumferential grooves 50 have a U-shaped cross-section.

FIG. 3 shows a further embodiment of a resonator muffler 1 in the diffuser 20 with also a plurality each concentric with the axis 11 annular circumferential grooves 50th

According to this embodiment FIG. 3 are all circumferential grooves 50, here four circumferential grooves 50, concentric with each other and arranged concentrically to the axis 11 on the radial wall 23 in the region of the blading 22 of the diffuser 20. With increasing radial distance from the axis 11, the width and the depth of the circumferential grooves 50 decrease. In other words, with increasing radial distance to the axis 11, the circumferential grooves 50 narrower and narrower and less deep. All circumferential grooves 50 here also have a U-shaped cross-section.

FIG. 4 shows an example of an acoustic eigenmode 60 in such acting as a resonator annular groove 50th

FIG. 4 shows 24 pressure maxima 61. Further, this eigen- or acoustic mode 60 is characterized by 12 so-called knot diameter 62 and a specific natural frequency. At the circumferential groove 50 passing sound waves, which are characterized by this natural frequency are reflected and the sound propagation over or past the circumferential groove 50 over.

If the passing sound wave has the same nodal diameter 62 as the acoustic mode 60 in the circumferential groove 50 (resonator), the reflection process is particularly effective.

Such resonator silencers 1 as described have an extremely efficient effect, in particular because they are used close to the sound source, impeller 10 and (optionally bladed 22) diffuser 20, so that further elaborate soundproofing measures, in particular for the entire piping system 29 of the radial compressor 100, are dispensed with can.

Claims (10)

1. Diffuser (20) for a radial compressor (100), which diffuser (20) has a substantially annular hollow chamber (30) which is delimited at least by one first radial side surface (21, 23),
   characterized in that
   the at least one first radial side surface (21, 23) has at least one substantially annularly encircling, empty circumferential groove (50) which forms an acoustic resonator, wherein a dimensioning of the at least one substantially annularly encircling, empty circumferential groove (50) defines a natural frequency and/or or an eigenform (60) of the substantially annularly encircling, empty circumferential groove (50), and the natural frequency and/or the eigenform (60) of the at least one substantially annularly encircling, empty circumferential groove (50) is tuned to a frequency to be reflected and/or to a sound wave to be reflected.
2. Diffuser (20) according to at least one of the preceding claims,
   characterized in that
   the at least one first radial side surface (21, 23) has multiple substantially annularly encircling, empty circumferential grooves (50) which are in particular situated concentrically with respect one another and which have in particular different dimensions in each case, in particular different depths and/or widths.
3. Diffuser (20) according to at least one of the preceding claims,
   characterized in that
   the annular hollow chamber (30) is delimited by a second radial side surface (21, 23) which is situated axially opposite the first radial side surface (21, 23), which second radial side surface (21, 23) has a substantially annularly encircling, empty circumferential groove (50) or multiple substantially annularly encircling, empty circumferential grooves (50) situated concentrically with respect one another.
4. Diffuser (20) according to at least the preceding claim,
   characterized in that
   the one substantially annularly encircling, empty circumferential groove (50) of the first radial side surface (21, 23) is situated opposite the one substantially annularly encircling, empty circumferential groove (50) of the second radial side surface (21, 23) with an axial or radial offset, or in that the multiple substantially annularly encircling, empty circumferential grooves (50), which are situated concentrically with respect one another, of the first radial side surface (21, 23) and the multiple substantially annularly encircling, empty circumferential grooves (50), which are situated concentrically with respect one another, of the second radial side surface (21, 23) are arranged opposite one another with an axial or radial offset.
5. Diffuser (20) according to at least one of the preceding claims,
   characterized in that
   the dimensioning which defines the natural frequency and/or the eigenform is a width and/or a depth and/or a radial position of the substantially annularly encircling, empty circumferential groove (50).
6. Diffuser (20) according to at least the preceding claim,
   characterized in that
   the natural frequency and/or the eigenform (60) of the at least one substantially annularly encircling, empty circumferential groove (50) are/is tuned to a vane impeller rotational frequency ("blade passing frequency") of the radial compressor or a second harmonic or third harmonic or fourth harmonic of the vane impeller rotational frequency of the radial compressor (100).
7. Diffuser (20) according to at least one of the preceding claims,
   characterized in that
   the substantially annular hollow chamber (30) has a blade arrangement (22).
8. Diffuser (20) according to at least the preceding claim,
   characterized in that
   the at least one substantially annularly encircling, empty circumferential groove (50) or each substantially annularly encircling, empty circumferential groove (50) is arranged in a region of the blade arrangement (22) or in that the at least one substantially annularly encircling, empty circumferential groove (50) or each substantially annularly encircling, empty circumferential groove (50) is arranged outside the region of the blade arrangement (22).
9. Diffuser (20) according to at least one of the preceding claims,
   characterized in that
   the at least one substantially annularly encircling, empty circumferential groove (50) has discontinuities.
10. Diffuser (20) according to at least one of the preceding claims, used in a radial compressor (100) or used in a radial turbine with a turbine guide ring positioned upstream of a turbine rotor of the radial turbine.

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