This application claims the priority of International Application No. PCT/DE2009/000230, filed Feb. 19, 2009, and German Patent Document No. 10 2008 010 283.0, filed Feb. 21, 2008, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a circulation structure for a turbo compressor. In addition, the invention relates to a turbo compressor as well as to an aircraft engine and a stationary gas turbine.
Circulation structures or recirculation structures for turbo compressors are known in the form of so-called casing treatments and hub treatments. The primary task of circulation structures called casing treatments and hub treatments is increasing the aerodynamically stable operating range of the compressor by optimizing the surge limit distance. An optimized surge limit distance makes higher compressor pressures possible and therefore a higher compressor load. The malfunctions responsible for a local flow separation and ultimately for pumping the compressor occur on the housing-side ends of the rotor blades of one or more compressor stages or on the hub-side radially inner ends of the guides blades, because the aerodynamic load in the compressor is the greatest in these regions. The flow in the region of the blade ends is stabilized by circulation structures. Stator-side circulation structures in the region of the housing-side ends of the rotor blades are called casing treatments, whereas rotor-side circulation structures in the region of the hub-side ends of the guides blades area called hub treatments.
Flow structures for a turbo compressor that are configured as casing treatments and hub treatments, which have annular chambers that can be traversed in the circumferential direction, are known from German Patent Document No. DE 103 30 084 A1. The annular chambers that can be traversed in the circumferential direction are arranged concentrically to an axis of the turbo compressor in the region of the free blade ends of a rotor blade ring or a guide blade ring, wherein the annular chambers radially border a main flow channel of the turbo compressor. Guide elements may be arranged within the annular chambers that can be traversed in the circumferential direction.
Starting herefrom, the objective of the present invention is creating a novel circulation structure for a turbo compressor.
According to the invention, several chambers that can be traversed in an axial direction are situated upstream of the or each annular chamber, when viewed from the main flow direction of the main flow channel.
The present invention proposes for the first time that several chambers that can be traversed in an axial direction be arranged upstream of the or each annular chambers that can be traversed in the circumferential direction, when viewed from the main flow direction of the main flow channel. The circulation structure according to the invention accordingly combines chambers that can be traversed in the axial direction, which do not have a circumferential connection, with at least one annular chamber, which can be traversed in the circumferential direction, wherein the or each annular chamber is situated downstream from the chamber that can be traversed in the axial direction that does not have a circumferential connection, when viewed in the main flow direction. This permits the formation of a gap vortex to be pulsatingly inhibited in terms of its development. A forming recirculation flow uses fluid that has heavy losses to influence the inflow of the rotor-side components, wherein the geometric properties of the chambers that can be traversed in the axial direction that do not have a circumferential connection generate a counter twist. Additional flow obstruction regions are shifted to the annular chambers with a circumferential connection.
Because of its simplicity, the circulation structure according to the invention guarantees very low losses. Loss-generating, three-dimensional flow phenomena may be inhibited effectively. Positive effects for the operational stability of the turbo compressor under partial load and full load with an overall positive change in the efficiency, particularly under full load, can be linked hereby. The simplicity of the circulation structure is connected with low manufacturing costs.
Preferred further developments of the invention are disclosed in the following description. Without being limited hereto, exemplary embodiments of the invention are described in greater detail on the basis of the drawings.
compressor, in particular for a compressor of a gas turbine, which can be configured as a casing treatment or as a hub treatment. Making reference to
In the exemplary embodiment in
The annular chamber 26 extends completely in the region of the free blade ends of the rotor blades 23 of the rotor blade ring 24, when viewed in the axial direction. The axial extension of the annular chamber 26 is identified in this case according to
In terms of the present invention, several chambers 27 that can be traversed in the axial direction are situated upstream of the annular chamber 26, when viewed in the main flow channel 22. The chambers 27 that can be traversed in the axial direction are configured as slots or axial grooves and are not connected to one another in the circumferential direction, therefore, the chambers 27 that can be traversed in the axial direction do not have a circumferential connection. An edge of the chambers 27 that is situated upstream when viewed in the main flow direction of the main flow channel 22 is identified by vk in
The chambers 27 that can be traversed in the axial direction are positioned in sections in the region of the free blade ends of the rotor blades 23 of the rotor blade ring 24. Thus, parameter o in
Parameter h in
A contour of the chambers 27 attaching to the downstream edge hk is inclined in relation to the radially outward contouring of the main flow channel 22 by the angle β. In addition, according to
Connections or discharge openings 30 of the chambers 27 that can be traversed in the axial direction in the main flow channel 22 are spaced apart axially or separated axially from a connection or discharge opening 31 of the annular chamber 26, wherein according to
It is pointed out at this point that the edges ak and ek of the annular chamber 26 as well as the edges vk, hk, dk, and sk of the chambers 27 that can be traversed in the axial direction and therefore the entrance surface of some may be described by any curves or splines. Edge surfaces attaching to these edges of the annular chamber 26 as well as the chambers 27 that can be traversed in the axial direction may be defined by generic hub surfaces. The geometry of each individual chamber 27 may deviate from the other chambers 27. This applies in particular to the angle of inclination γ of chambers 27, the circumferential distance s of the chambers 27 and the circumferential width c of the chambers 27.
In the embodiment in
As an alternative to rotation, a local translation may also be used to generate the edge surfaces or outer surfaces of the chambers 26 and 27.
The parameters α, β, h, t and b may have any value in the exemplary embodiment in
The parameter a must assume a value of greater than zero for an axial separation of the chambers 27 that can be traversed in the axial direction from the annular chamber 26 or for an axial separation of the corresponding discharge openings 30, 31.
In the exemplary embodiment in
Thus, in
The invention may also be used if the turbo compressor has a tandem rotor with two directly successive rotor blade rings and/or two directly successive guide blade rings.
The circulation structure according to the invention is preferably used with turbo compressors, in particular compressors of a gas turbine configured as an aircraft engine or a stationary gas turbine.
Number | Date | Country | Kind |
---|---|---|---|
10 2008 010 283 | Feb 2008 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/DE2009/000230 | 2/19/2009 | WO | 00 | 8/20/2010 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2009/103278 | 8/27/2009 | WO | A |
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Number | Date | Country | |
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20100329852 A1 | Dec 2010 | US |