EP3760876A1 - Diffuser for a turbomachine - Google Patents

Abstract

The invention relates to an arrangement (ARA) with a diffuser (DFF) for a fluid flow machine (CMP) with an impeller (IMP) upstream of the diffuser (DFF), the diffuser (DFF) and the impeller (IMP) extending in a ring around an axis (X) extend along a circumferential direction (CDR), the rib guide vanes (RPV) extending from the housing side (CSS) along 25% -50% of the diffuser channel width (ADW) in the direction of the hub side (HBS) and having leading edges (LEE) , which are arranged on a mean rib leading edge diameter (RLE), the impeller (IMP) having impeller blades (BLD), the impeller blades (BLD) having rotor trailing edges (TRE), the rotor trailing edges (TRE) on average over the respective blade height (AFH) ) are arranged on a mean rotor trailing edge diameter (TRI). To improve the aerodynamic effect of the diffuser, it is proposed that the ratio (RDT) of a rib inlet edge diameter to an average rotor outlet edge diameter should be: 1.04 <RLE / TRI <1.1. At the same time, the required installation space can be reduced.

Description

The invention relates to an arrangement with a diffuser for a turbomachine with an impeller upstream of the diffuser, the diffuser and the impeller extending annularly around an axis along a circumferential direction, the ribbed guide vanes extending along the vane height between two diffuser boundary walls starting from a diffuser boundary wall on one Housing side extending in the direction of a diffuser boundary wall on a hub side, the rib guide vanes extending from the housing side along 25% -50% of the diffuser channel width in the direction of the hub side, the rib guide vanes having leading edges which are arranged on a mean rib leading edge diameter, the impeller having impeller blades wherein the impeller blades have rotor trailing edges, the rotor trailing edges being arranged on a mean rotor trailing edge diameter over the respective blade height. The invention also relates to a turbomachine with such an arrangement.

In the case of radial compressors, the fluid leaves the impeller radially outwards and from there reaches the diffuser, which typically also has a radial flow from the inside to the outside. Diffusers can be bladed or bladed. In the case of the bladed types, a distinction is made between low solidity diffusers [LSD] with little blade overlap (with guide vanes that have a relatively large distance from one another in the circumferential direction in relation to their radial extent) and channel diffusers - also known as aerodynamic diffusers [AE diffuser] - distinguished. Due to the disadvantages with regard to the driving range, AE diffusers are very rarely used. LSDs, on the other hand, offer a significantly better and more extensive driving range than AE diffusers. Almost all bladed diffusers today are LSDs.

• Unterdrücken von Rotating Stall, welcher im Falle eines unbeschaufelten Ringraums ggf. auftreten könnte
• Steigerung des Wirkungsgrades der Stufe durch Aufrichten der Strömung und durch Vergleichmäßigung der Strömung über der Kanalhöhe. Dies führt zu einer Reduktion von Verlusten in den nachgeschalteten Komponenten wie Rückführstufe oder Spirale.
• Besserer Kennlinienanstieg zur Pumpgrenze.

LSDs are used for the following reasons:

• Suppression of rotating stall, which could possibly occur in the case of a non-bladed annulus
• Increase in the efficiency of the stage by straightening the flow and by equalizing the flow above the channel height. This leads to a reduction in losses in the downstream components such as the recirculation stage or spiral.
• Better increase in characteristic curve to surge limit.

• Reduzierter Fahrbereich (schmalere Kennlinie) im Vergleich zur unbeschaufelten Variante
• Höherer Lärmpegel
• Höhere Laufradanregung
• Notwendige radiale Erstreckung des Diffusors größer als für den unbeschaufelten Diffusor
• Notwendige Sammelspiralgehäusegröße nimmt mit LSD zu, da die Umfangskomponente der Geschwindigkeit (Transportgröße in der Spirale) durch den LSD reduziert wird.

Disadvantages of LSDs are:

• Reduced travel range (narrower characteristic) compared to the non-bladed variant
• Higher noise level
• Higher impeller excitation
• The necessary radial extension of the diffuser is greater than that for the unbladed diffuser
• Necessary collecting volute casing size increases with LSD, since the circumferential component of the speed (transport size in the volute) is reduced by the LSD.

Diffusers for radial machines are already from the EP 2 650 546 A1 known. It is proposed there to arrange the guide vanes of the diffuser in an inclined shape in a standing diffuser arranged behind the impeller (dihedral vanes). With the LSD in particular, this aerodynamic measure is intended to achieve a reduced pressure loss.

From the WO2019057412A1 , WO2019057413A1 , WO2019057414A1 arrangements of impellers and diffusers of, in particular, turbo-compressors are already known.

From the US4850795A and the EP446900B1 arrangements with rib guide vanes are already known.

Based in particular on the disadvantages described, the main task of the invention is to reduce the radial installation space requirement of an LSD so that the otherwise increased radial installation space requirement is no longer so significant compared to an unbladed diffuser.

To solve the problem, a diffuser or an arrangement and a flow machine with such a diffuser with the features defined at the outset is proposed, which has the additional features of the characterizing part of claim 1. The dependent claims referring back contain advantageous developments of the invention.

Terms such as radial, axial, tangential or circumferential direction relate to the axis defined at the outset, around which the diffuser extends in an annular manner. In the case of a turbo compressor or a radial turbo compressor, this axis is coaxial with the axis of rotation of the rotor.

All angle specifications here always relate to the objective angles on the actual geometric shapes - in short: metal angles.

The term circumferential tangent (in the present case also denoted by the reference symbol CDT) always means a tangent that touches a circular line around the central axis, the circle radius and the point of contact each clearly arising from the context for the person skilled in the art.

The invention understands a profile center line to be an imaginary line that extends through the center of a blade profile. Here, the blade profile is understood as a two-dimensional shape. The profile center line can be constructed in this two-dimensional form, for example by connecting the centers of all inscribed circles by means of a line - the profile center line.

The diffuser is defined axially by diffuser boundary walls. The term “diffuser boundary walls” is not to be understood in such a way that the diffuser boundary walls always have an axial surface normal. Rather, this term is intended to mean that the diffuser boundary walls in any case have a radial extent and - even if they have an oblique course with respect to the radial or axial direction - limit the diffuser in the axial direction. Another advantageous development of the invention provides that the axial distance between diffuser boundary walls widens in the radial direction.

According to the invention, the term turbomachine relates to radial turbomachines which provide a deflection of the process fluid. The application for a radial turbo compressor is of primary importance. In the case of the radial turbo compressor in particular, the diffuser is a flow-guiding component of the stator, which is located downstream of the impeller outlet. As a rule, the flow rate of the process fluid is delayed in the diffuser, so that a pressure build-up results in accordance with Bernoulli's principles.

In the case of the radial turbo compressor and a diffuser that extends essentially radially outward, the diffuser effect results from the radial increase in the cross-sectional area through which the flow passes. Also of importance is a change in the diffuser channel width, which usually results from the axial extension of the clear width of the diffuser. In principle, the diffuser can also extend in a manner deviating from the radial direction. Most diffusers, however, extend largely radially. The diffuser channel width is limited by the diffuser boundary walls provided on both sides. In the case of a purely radially extending diffuser without axial widening, the diffuser boundary walls also run purely radially. Due to the axial intake of a radial turbo compressor and the radial output of the process fluid from the impeller, in the impeller is deflected from axially to radially. The impeller is usually constructed with a wheel disc which connects the impeller to the shaft with a shaft-hub connection. The side that does not have the axial suction of the impeller is referred to here as the hub side. The other opposite axial side is referred to as the housing side. In the case of impellers that have a cover disk on the housing side, this housing side is also often referred to as the cover disk side. The invention understands a blade height as the extension of the blade perpendicular to the main flow direction. If one follows a flow thread, representative of the main flow direction, through the arrangement of the invention, for example through the diffuser, then this flow thread extends essentially perpendicular to the direction of the blade height. If this flow thread extends approximately centrally through the arrangement, it will be approximately 50% of the blade height.

The feature according to the invention that for the ratio RDT of a rib inlet edge diameter to an average rotor outlet edge diameter applies:
1.04 <ratio RDT <1.1 leads to a particularly effective and space-saving consideration of the difference between the housing side and the hub side.

For the ribbed guide vanes, a rib entry angle REA is defined with respect to the entry edge angle of the diffuser guide vanes and is preferably between 14 ° and 22 °. This geometry effectively takes into account the peculiarities of the ribbed vanes and the flow technology downstream of the impeller.

With an analogous definition of the rib exit angle, a further advantageous development provides that, averaged over the blade height, the rib angle difference between the rib entry angle and rib exit angle is designed as a metal angle between 4 ° and + 11 °, preferably between 6 ° to 10 °.

Here, the fin guide vanes have a vane overlap for each position of the vane height, which is defined as the ratio of a chord length of the respective fin guide vane to the circumferential pitch of the arrangement of the fin guide vanes. The invention understands the profile chord to be the imaginary connecting line between the leading edge of the profile and the trailing edge or trailing edge. The circumferential division - also often referred to simply as a division - is understood to mean the distance in the circumferential direction between the leading edges of the fin guide vanes. An advantageous development of the invention in this regard provides that the mean blade overlap (SLD) of the rib guide vanes is between 0.6 <SLD <0.9, preferably between 0.65 <SLD <0.75.

An advantageous further development of the invention provides that the impeller has an axial impeller outlet width at the outlet, the diffuser having an axial diffuser duct inlet width at the inlet, an annular space width ratio being defined as the axial diffuser duct inlet width to the axial impeller outlet width, the annular space width ratio ACW preferably 0.8 <ACW < 1, particularly preferably between 0.85 <ACW <0.98. This ratio leads to surprisingly good aerodynamic results with reduced radial space requirements.

Another advantageous development of the invention provides that the diffuser has, downstream of the ribbed guide vanes, diffuser guide vanes which, starting from the housing side, extend along the diffuser channel width to the hub side. The diffuser guide vanes are arranged downstream of the rib guide vanes for at least 70% of their chord lengths.

The ribbed guide vanes also take into account the fact that the process fluid emerging from the impeller has a different flow distribution and speed distribution on the housing side has than on the hub side. To compensate for this difference, the ribbed guide vanes are provided in front of the actual diffuser guide vanes, so that these differences are better compensated and the most homogeneous outflow possible takes place behind the outlet of the diffuser.

Furthermore, the invention proposes as an advantageous development that the ribbed guide vanes and / or the diffuser guide vanes have a curved and profiled profile. Profiled here means that the blade profile does not have a constant thickness over the extent in the main flow direction, but is aerodynamically adapted with regard to the profile thickness distribution.

As a rule, the blade or the blade profile on the pressure side is designed to be more concave over a wider area than on the suction side - accordingly, the blade profile on the suction side is designed to be convex over a further area of extent.

Another advantageous development of the invention provides that for each position along the profile center line of the blade profile of the diffuser guide vanes, an angle of attack is defined as the mathematically positive angle from the circumferential tangent to the tangent at the profile center line. Here, a leading edge angle is an angle of attack at the leading edge and an exit edge angle is an angle of attack at the trailing edge of the diffuser guide vane.

Preferably, where the leading edge angle is between 23 ° <LEA <30 ° ..

For the difference between the leading edge angle and the trailing edge angle averaged over the blade height, the following preferably applies: -4> leading edge angle - trailing edge angle> 10 °.

A negative difference between the leading edge angle and the exit angle or the rib entry angle and the rib exit angle (rib angle difference RFA) indicates that the blade tapers more tangentially than the inlet is designed. A flow fluid that would at least largely or completely follow such a blade design has a more tangential flow orientation after flowing through such a blade arrangement with such a negative difference.

An advantageous development provides that the ratio of the number of rib guide vanes to the number of diffuser guide vanes is 0.5, 1 or 2. It is useful if the arrangement has 8-24 diffuser guide vanes.

Another advantageous development provides that in the area of the inlet edges of the diffuser guide vanes the diffuser has an axial diffuser guide vane inlet width, with the diffuser having an axial diffuser guide vane outlet width in the area of the outlet edges of the diffuser guide vanes, a guide vane inlet guide vane outlet width being defined as the axial diffuser guide vane width ratio to the diffuser guide vane outlet width $$1,0<\mathrm{AVW}<1,\mathrm{4th}$$

An advantageous further development of this feature provides that the diffuser boundary wall on the hub side extends less obliquely to the radial direction than the diffuser boundary wall on the housing side, such that at least 80% of the axial expansion results from the inclination of the diffuser boundary wall on the housing side.

The invention also relates to a turbomachine with an arrangement of the type defined above.

Figur 1

einen schematischen Längsschnitt entlang einer Drehachse durch eine erfindungsgemäße Strömungsmaschine mit einem erfindungsgemäßen Diffusor bzw. einer erfindungsgemäßen Anordnung,

Figur 2

einen Schnitt II-II entlang einer Hauptströmungsrichtung gemäß Figur 1,

Figur 3

das Detail III aus Figur 2,

Figur 4

eine schematische Darstellung eines Längsschnitts durch eine Strömungsmaschine beschränkt auf das Detail des Diffusors,

Figur 5

den Schnitt V-V aus Figur 4,

Figur 6

eine schematische Darstellung eines Längsschnitts durch einen Diffusor mit aufgeweiteter Diffusorkanalbreite mit Rippenleitschaufeln.

In the following, the invention is illustrated with the aid of various figures for better understanding, showing preferred exemplary embodiments. Show it:

Figure 1

a schematic longitudinal section along an axis of rotation through a turbomachine according to the invention with a diffuser according to the invention or an arrangement according to the invention,

Figure 2

a section II-II along a main flow direction according to Figure 1 ,

Figure 3

the detail III Figure 2 ,

Figure 4

a schematic representation of a longitudinal section through a turbomachine limited to the detail of the diffuser,

Figure 5

the section VV Figure 4 ,

Figure 6

a schematic representation of a longitudinal section through a diffuser with widened diffuser channel width with ribbed guide vanes.

In the figures, the same reference symbols denote functionally identical components.

Figure 1 shows a fluid flow machine CMP with an arrangement ARA with a diffuser DFF and an impeller IMP arranged upstream of the diffuser DFF. The impeller IMP and the diffuser DFF extend annularly along a circumferential direction CDR of an axis X with an axis of rotation ROT. The impeller IMP is fastened in a specific axial position to a shaft SHT which is rotatably mounted about the axis of rotation ROT or the axis X arranged coaxially to the axis of rotation ROT. The impeller IMP has a wheel disc HUB, impeller blades BLD and a cover plate SHR, the impeller blades BLD being attached between the wheel disc HUB and the cover plate SHR, forming flow channels. A process fluid PFL is sucked in axially and deflected outward in the radial direction, where it exits the rotating impeller IMP during operation and enters a static diffuser DFF.

Ribbed guide vanes RPV of the static diffuser DFF homogenize and correct the speed distribution of the exiting process fluid PFL before it is introduced into a spiral VLT. The rib guide vanes RPV extend along the vane height AFH between two diffuser boundary walls LDW starting from a diffuser boundary wall LDW on a housing side CSS in the direction of a diffuser boundary wall LDW on a hub side HBS.

An advantageous further development of the invention provides that the impeller IMP has an axial impeller outlet width AXW at the outlet, the diffuser DFF having an axial diffuser channel inlet width IDW at the inlet, an annular space width ratio ACW being defined as the axial diffuser channel inlet width IDW to the axial impeller outlet width (AXW):
0.8 <ACW <1, the following applies particularly preferably: $$0,85<\mathrm{ACW}<0,98$$

Figure 2 shows a section according to II-II of FIG Figure 1 schematic. In contrast to the circumferential direction CDR illustrated there, in a direction of rotation RDR, the impeller IMP is shown rotatable about the X axis. The impeller blades BLD of the impeller IMP are shown schematically with a concave pressure side PRS and a convex suction side SCS - as are the ribbed guide vanes RPV. The rotor trailing edges RRE of the impeller blades BLD are set back somewhat compared to the maximum diameter IPD of the impeller IMP on a rotor trailing edge diameter TRI. Downstream there are leading edges LEE of the fin guide vanes RPV on a leading edge diameter DLE.

According to the invention, the following applies to the ratio RDT of the rib inlet edge diameter RLE to the mean rotor outlet edge diameter TRI: 1.04 <RLE / TRI <1.1.

Figure 3 shows a detail that is in the Figure 2 is shown with III. The ones in the Figure 3 The illustrated relationships relate to angular relationships on ribbed guide vanes RPV and also to diffuser guide vanes VNS, which with the respective blade height AFH not only extend over part of the diffuser channel width ADW, but over the entire axial distance of the diffuser boundary walls LDW. The relationships shown in this presentation apply mutatis mutandis to diffuser guide vanes VNS or ribbed guide vanes RPV, so that in FIG Figure 3 partly also identical reference symbols - which indicate an identical component meaning - and relationships are reproduced for both arrangements.

The two in Figure 3 illustrated exemplary ribbed guide vanes RPV or diffuser guide vanes VNS (hereinafter referred to as Figure 3 only referred to as diffuser guide vanes VNS) have for each position of the vane height AFH in their arrangement to each other a vane overlap SLD, which is defined as the ratio of a chord length CHD of the respective diffuser vane VNS to the circumferential pitch CCP of the arrangement of the ribbed vanes RPV or diffuser vanes VNS.

According to an advantageous development of the invention, the mean blade overlap SLD of the ribbed guide vanes RPV is between 0.6 <SLD <0.9, particularly preferably 0.65 <SLD <0.75.

For each position along the profile center line SCL of the blade profile of the diffuser guide vanes VNS, an angle of attack PMA is defined as the mathematically positive angle from the circumferential rod CDT to the tangent PMT at the profile center line SCL of the profile. Here, a leading edge angle LEA or rib entry angle REA is an angle of attack PMA at the leading edge LEE of a diffuser guide vane VNS or rib guide vane RPV. An exit edge angle EXA is an angle of attack PMA at an exit edge TRE of the diffuser guide vanes VNS.

According to a further development of the invention, it is preferred that a rib entry angle REA is a rib angle of attack RMA at an entry edge LEE of a rib guide vane RPV, where the following applies to the mean rib entry angle REA: $$12°<\mathrm{REA}<\mathrm{20th}°\mathrm{.}$$

For a difference between the leading edge angle LEA and the trailing edge angle EXA or rib exit angle RXA averaged over the blade height AFH, the following applies for the rib guide vanes RPV: $$\mathrm{4th}°<\mathrm{REA}-\mathrm{RXA}<11°,\mathrm{prefers}\mathrm{6th}°<\mathrm{REA}-\mathrm{RX}<10°\mathrm{.}$$

The Figure 4 and 5 also the Figure 6 show different views of an embodiment with diffuser guide vanes VNS arranged downstream of the ribbed guide vanes RPV, which, starting from the housing side CSS, extend along the entire diffuser channel width ADW in the direction of the hub side HBS.

In these arrangements with diffuser guide vanes VNS arranged downstream of the ribbed guide vanes RPV, the leading edge angle LEA of the diffuser guide vanes VNS is between 23 ° <LEA <30 °, whereby the following preferably applies for a difference leading edge angle (LEA) - exit edge angle (EXA) for the diffuser guide vanes VNS: $$-\mathrm{4th}°<\mathrm{LEA}-\mathrm{EXA}<10°\mathrm{.}$$

For the rib inlet angle REA, if a diffuser guide vane VNS is arranged upstream of the rib guide vane RPV, the following preferably applies: $$12°>\mathrm{REA}>\mathrm{20th}°\mathrm{.}$$

For the rib exit angle RXA - that is, the rib angle of incidence at a rib exit edge of the rib guide vanes RPV, in connection with the rib entry angle REA, the following applies to the difference RFA between rib entry angles REA and rib outlet angle RXA averaged over the blade height AFH applies: $$\mathrm{4th}°>\mathrm{REA}-\mathrm{RXA}>11°\mathrm{.}$$

The ratio of the number of rib guide vanes RPV to the number of diffuser guide vanes VNS is particularly expediently: 0.5 or 1 or 2. The arrangement ARA has 8-24 diffuser guide vanes VNS particularly expediently.

For the diffuser blades VNS, preferably averaged over the blade height AFH, a blade overlap SLD between 0.45 and 0.9, particularly preferably between 0.65 and 0.75, applies. The blade overlap SLD is defined here as the ratio of a profile chord length CHD of the respective diffuser blade VNS to the circumferential pitch CCP of the arrangement of the diffuser blades VNS.

Figure 6 shows the combination of the axial expansion of the diffuser channel width or the inclined housing-side diffuser boundary wall LDW with the arrangement of the ribbed guide vanes RPV upstream of the diffuser guide vanes VNS. Furthermore shows Figure 6 an expansion of the axial distance between the axial diffuser boundary walls LDW with increasing radial extent. Here, the diffuser boundary walls LDW are designed in such a way that the diffuser boundary wall LDW extends less obliquely to the radial direction on the hub side HUB than the diffuser boundary wall LDW on the housing side SHR. This results in an axial expansion of at least 80% exclusively from the inclination of the diffuser boundary wall LDW on the CSS side of the housing.

Specifically, it is preferred that in the area of the inlet edges LEE of the diffuser guide vanes VNS the diffuser DFF has an axial diffuser guide vane inlet width IVW, wherein in the area of the outlet edges of the diffuser guide vanes VNS the diffuser DFF has an axial diffuser guide vane outlet width AVW defined as a diffuser guide vane outlet width AVW axial diffuser guide vane outlet width EVW for axial diffuser guide vane inlet width IVW $$1,0<\mathrm{AVW}<1,\mathrm{4th}$$

So that there is no impact on the diffuser guide vanes VNS by wake dents in the flow from the ribbed guide vanes RPV, it is preferred that the leading edges LEE of the diffuser guide vanes VNS outside a surrounding area of +/- 10% of the pitch CCP of the ribbed guide vanes RPV in the circumferential direction CDR starting from a Tangent to the profile center line RHD of the rib guide vane RPV at the trailing edge TRE of the rib guide vanes RPV arranged upstream of the diffuser guide vanes VNS.

Particularly preferably, the number of diffuser guide vanes VNS is twice as high as that of the ribbed guide vane RPV and the diffuser guide vanes VNS are particularly preferably located, starting from a tangent to the profile center line RHD of the ribbed guide vane RPV, on the trailing edge TRE of the ribs VNS arranged upstream of the diffuser guide vanes RPV Ribbed vanes RPV.

Claims (20)

1. Arrangement (ARA) comprising a diffuser (DFF) for a turbomachine (CMP) with an impeller (IMP) upstream of the diffuser (DFF),
wherein the diffuser (DFF) and the impeller (IMP) extend annularly around an axis (X) along a circumferential direction (CDR),
wherein the rib guide vanes (RPV) extend along the vane height (AFH) between two diffuser boundary walls (LDW) starting from a diffuser boundary wall (LDW) on one housing side (CSS) in the direction of a diffuser boundary wall (LDW) on a hub side (HBS),
with rib guide vanes (RPV) extending from the housing side (CSS) along 25% -50% of a diffuser channel width (ADW) in the direction of the hub side (HBS),
wherein the rib guide vanes (RPV) have leading edges (LEE) which are arranged on a mean rib leading edge diameter (RLE),
the impeller (IMP) having impeller blades (BLD), the impeller blades (BLD) having rotor trailing edges (RRE),
the rotor trailing edges (RRE) being arranged on a mean rotor trailing edge diameter (TRI) over the respective blade height (AFH),
characterized in that
for the ratio (RDT) of the rib leading edge diameter (RLE) to the mean rotor trailing edge diameter (TRI) the following applies: 1.04 <RLE / TRI <1.1. 2. Arrangement (ARA) according to claim 1,
wherein a rib profile centerline is defined as a profile centerline (SCL) of an airfoil of the fin guide vanes (RPV),
A rib angle of attack (RMA) is defined as the mathematically positive angle of a circumferential tangent (CDT) at the respective position of the tangent there on the rib profile center line,
wherein a rib entry angle (REA) is a rib angle of attack (RMA) at a leading edge (LEE) of a rib guide vane (RPV),
where for the mean rib entry angle (REA) applies: $$12°<\mathrm{REA}<\mathrm{20th}°\mathrm{.}$$

3. Arrangement (ARA) according to claim 2, wherein a rib exit angle (RXA) is a rib angle of attack (RMA) at a trailing edge (TRE) of the rib guide vanes (RPV), wherein for the rib angle difference (RFA) between rib entrance angle (REA) and rib exit angle (RXA ) averaged over the blade height (AFH) applies: $$\mathrm{4th}°<\mathrm{REA}-\mathrm{RXA}<11°\mathrm{.}$$

4. Arrangement (ARA) according to claim 3, wherein the following applies for the rib angle of attack difference (RFA) averaged over the blade height (AFH): 6 ° <REA-RXA <10 °. 5. Arrangement (ARA) according to one of claims 1-3, wherein the rib guide vanes (RPV) have a chord length (CHD) for each position of the rib height (RFH),
wherein the rib guide vanes (RPV) for each position of the rib height (RFH) have a vane cover (SLD) which is defined as the ratio of the chord length (CHD) of the respective rib guide vanes (RPV) to a circumferential pitch (CCP) of the arrangement of the fin guide vanes (RPV) ),
where the mean blade overlap (SLD) of the fin guide vanes (RPV) is between 0.6 <SLD <0.9. 6. Arrangement (ARA) according to claim 5, wherein the mean blade overlap (SLD) of the rib guide vanes (RPV) is between 0.65 <SLD <0.75. 7. Arrangement (ARA) according to one of claims 1 - 6, wherein the impeller (IMP) has an axial impeller outlet width (AXW) at the outlet,
wherein the diffuser (DFF) has an axial diffuser channel inlet width (IDW) at the inlet,
An annulus width ratio (ACW) is defined as the axial diffuser duct inlet width (IDW) to the axial impeller outlet width (AXW) with: $$0,\mathrm{8th}<\mathrm{ACW}<1.$$

8. Arrangement (ARA) according to claim 7, wherein the annulus width ratio (ACW)
is between 0.85 <ACW <0.98. 9. Arrangement (ARA) according to one of claims 1 - 8, wherein the diffuser (DFF) at least partially downstream of the ribbed guide vanes (RPV) has diffuser guide vanes (VNS) which extend along their vane height (AFH) between the two diffuser boundary walls (LDW) from the diffuser delimitation wall (LDW) on a housing side (CSS) to the diffuser delimitation wall (LDW) on a hub side (HBS). 10. Arrangement (ARA) according to claim 9, wherein the diffuser guide vanes (VNS) are arranged to at least 70% of the chord lengths (CHD) downstream of the rib guide vanes (RPV). 11. Arrangement (ARA) according to claim 9 or 10, wherein the ratio of the number of fin guide vanes (RPV) to the number of diffuser guide vanes (VNS) is 0.5, 1 or 2. 11. Arrangement (ARA) according to claim 10, wherein the arrangement (ARA) has 8-24 diffuser guide vanes (VNS). 12. Arrangement (ARA) according to one of claims 9-11, wherein the diffuser blades (VNS) have a blade cover (SLD) for each position of the blade height (AFH), which is defined as the ratio of a chord length (CHD) of the respective diffuser blade ( VNS) for the circumferential division (CCP) of the arrangement of the diffuser blades (VNS),
wherein the blade overlap (SLD) of the diffuser guide blades (VNS) is on average between 0.45 and 0.9, preferably between 0.65 and 0.75. 14. Arrangement (ARA) according to one of claims 1 - 12, wherein the ribbed guide vanes (RPV) and / or the diffuser guide vanes (VNS) have a curved and profiled profile. 15. Arrangement (ARA) according to one of claims 9-14, wherein for each position along the profile center line (SCL) of the blade profile of the diffuser guide vanes (VNS) an angle of attack (PMA) is defined as the mathematically positive angle of the circumferential tangent (CDT) the respective position of the profile center line (SCL) on the tangent (PMT) there on the profile center line (SCL),
where a leading edge angle (LEA) is an angle of attack (PMA) at the leading edge (LEE),
where the leading edge angle (LEA)
is between 23 ° <LEA <30 °. 16. Arrangement (ARA) according to claim 15,
where a trailing edge angle (EXA) is an angle of attack (PMA) at the trailing edge (TRE) of the diffuser guide vanes (VNS),
where for a guide vane angle difference (DFA) leading edge angle (LEA) - trailing edge angle (EXA) applies: $$-\mathrm{4th}°<\mathrm{LEA}-\mathrm{EXA}<10°\mathrm{.}$$

17. Arrangement (ARA) according to one of claims 9-16,
wherein in the area of the leading edges (LEE) of the diffuser guide vanes (VNS) the diffuser (DFF) has an axial diffuser guide vane inlet width (IVW),
wherein in the area of the outlet edges of the diffuser guide vanes (VNS) the diffuser (DFF) has an axial diffuser guide vane outlet width (EVW),
wherein a vane annulus width ratio (AVW) is defined as an axial diffuser vane exit width (EVW) to axial diffuser guide vane inlet width (IVW) $$1,0<\mathrm{AVW}<1,\mathrm{4th}$$

18. Arrangement (ARA) according to claim 17,
The widening from the axial diffuser guide vane inlet width (IVW) to the axial diffuser guide vane outlet width (EVW) results to at least 80% from an inclination of the diffuser boundary wall (LDW) on the housing side (CSS) in relation to the radial direction. 19. Arrangement (ARA) according to one of claims 9-17,
The leading edges (LEE) of the diffuser guide vanes (VNS) outside of a surrounding area of +/- 10% of the pitch (CCP) of the fin guide vanes (RPV) in the circumferential direction (CDR) starting from a tangent to the profile center line (RHD) of the fin guide vane (RPV) at the trailing edge (TRE) of the rib guide vanes (RPV) arranged upstream of the diffuser guide vanes (VNS). 20. Turbomachine (CMP) with an arrangement (ARA) according to at least one of claims 14 to 18.

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