Shroud arrangement of a row of blades of stator vanes or rotor blades

Patent metadata

Field	Value
Publication number	US-10316677-B2
Application number	US-201615094187-A
Country	US
Kind code	B2
Filing date	Apr 8, 2016
Priority date	Apr 9, 2015
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A cover band assembly of a blade row of stator or rotor blades is provided. The cover band assembly comprises a blade row that is arranged inside a main flow path of a continuous-flow machine and has multiple blades which respectively have a front edge and a rear edge; and a cover band of the blade row that is at least partially embedded in a component or a component group as regarded in a longitudinal section of the continuous-flow machine, wherein a cavity is formed that surrounds the cover band and is connected to the main flow path by way of two cavity openings, wherein the front cavity opening is provided upstream of the front edge and the rear cavity opening is provided downstream of the rear edge of the blades of the blade row. Here, the cover band has a leading edge and a trailing edge.

First claim

The invention claimed is:

1. A cover band assembly of a blade row of stator or rotor blades, comprising:
a blade row arranged inside a main flow path of a continuous-flow machine and having multiple blades which respectively have a front edge and a rear edge,
a cover band of the blade row that is at least partially embedded in a component or a component group as regarded in a longitudinal section of the continuous-flow machine, wherein a cavity is formed that surrounds the cover band and is connected to the main flow path by front and rear cavity openings, wherein the front cavity opening is provided upstream of the front edge and the rear cavity opening is provided downstream of the rear edge of the blades of the blade row such that a leakage flow entering the front cavity opening flows through the cavity and exits the rear cavity opening, there being an imaginary connection line between the front cavity opening and the rear cavity opening at the main flow path,
wherein the cover band has a leading edge and a trailing edge, and
wherein a contour the cover band is retracted away from the main flow path into the cavity in an area of at least one chosen from the leading edge and the trailing edge in at least one longitudinal section of the continuous-flow machine;
wherein the contour of the cover band which is facing towards the main flow path is formed in such a manner in an area of the leading edge that a front passage is formed adjacent to the main flow path upstream of the blade front edge between the contour of the cover band and an outer contour of the cavity, wherein the front passage guides the leakage flow entering the front cavity opening with an upstream directional component against the main flow, and accordingly a longitudinal axis of the front passage forms an acute angle in an upstream direction between the longitudinal axis of the front passage and the connection line;
wherein the contour of the cover band which is facing towards the main flow path is formed in such a manner in an area of the trailing edge that a rear passage is formed adjacent to the main flow path downstream of the blade rear edge between the contour of the cover band and the outer contour of the cavity, wherein the rear passage guides the leakage flow exiting the rear cavity opening with an upstream directional component against the main flow, and accordingly a longitudinal axis of the rear passage forms an acute angle in a downstream direction and in a direction toward the cavity between the longitudinal axis of the rear passage and the connection line.

2. The cover band assembly according to claim 1 , wherein:
the cover band is arranged, as regarded in the axial direction of the continuous-flow machine, respectively between at least first and second sets of reference points that are located at an edge of the main flow path of the continuous-flow machine;
the first set of reference points are formed by base points of the front edge and the rear edge of a blade row that is arranged upstream of the cover band, or—if this blade row is not present—by two boundary points of the main flow path, which are located at 100% and 150% of the axial extension of the blade row to which the cover band is applied upstream of the front edge of the blade row to which the cover band is applied,
the second set of reference points are formed by the base points of the front edge and the rear edge of the blade row that is arranged downstream of the cover band, or—if this blade row is not present—by two boundary points of the main flow path, which are located at 100% and 150% of the axial extension of the blade row to which the cover band is applied downstream of the rear edge of the blade row to which the cover band is applied, and
the cover band is retracted into the cavity in at least one location of the circumference and in at least one of the areas of the front or rear edge of the respective blade row to below the connection line, which is formed by a third-degree polynomial interpolation or a third-degree spline interpolation through the first set and second set off reference points.

3. The cover band assembly according to claim 2 , wherein a cover band retraction that is defined as a distance between the connection line and a curve through a location of maximal cover band retraction that is extending at a constant distance to the connection line, and, is at least 1% of a ring channel width at the blade edge that is closest to the location of maximal cover band retraction, wherein the cover band retraction in the front edge area is determined directly at the blade front edge and the cover band retraction in the rear edge area is determined directly at the blade rear edge if the location of maximal cover band retraction is located within the blade row between the front and the rear edge.

4. The cover band assembly according to claim 1 , wherein the leading edge of the cover band includes a chamfer or a rounding for enhanced flow control.

5. The cover band assembly according to claim 1 , wherein the leading edge of the cover band has a protruding profile for enhanced flow control.

6. The cover band assembly according to claim 1 , wherein the trailing edge of the cover band includes a chamfer or a rounding for enhanced flow control.

7. The cover band assembly according to claim 1 , wherein the trailing edge of the cover band has a protruding profile for enhanced flow control.

8. The cover band assembly according to claim 1 , wherein, at the front cavity opening, an edge of a component that confines the front cavity opening in the upstream direction is formed so as to be chamfered or rounded or has a protruding profile at the main flow path boundary.

9. The cover band assembly according to claim 1 , wherein, at the rear cavity opening, an edge of a component that confines the rear cavity opening in the downstream direction is chamfered or rounded or has a protruding profile at the main flow path boundary.

10. The cover band assembly according to claim 1 , wherein a cover band retraction is provided in the area of the leading edge as well as in the area of the trailing edge.

11. The cover band assembly according to claim 1 , wherein a cover band retraction, as well as a shape of a respective edge of the cover band vary periodically in a circumferential direction of the blade row, wherein a period P of a circumferentially directed variation of the cover band retraction and of a cover band edge shape has a whole-number ratio to a blade pitch S of the blade row, according to n×P=S, wherein n is a natural number equal to or greater than 1.

12. The cover band assembly according to claim 11 , wherein a maximum of the cover band retraction as regarded in the circumferential direction of the blade row is formed respectively at half a distance between two neighboring blades of the blade row.

13. The cover band assembly according to claim 1 , wherein, at least in one longitudinal section of the continuous-flow machine, the contour of the cover band is retracted away from the main flow path into the cavity in at least one chosen from the area of the leading edge and in the area of the trailing edge such that at least one chosen from the following occurs: an overall smooth course of the main flow path boundary is no longer present and instead the retracted leading edge forms a recess with respect to a section of the main flow path boundary that is provided directly upstream of the cover band, and a section of the main flow path boundary that is provided directly downstream of the cover band forms a protrusion with respect to the retracted trailing edge, as regarded in the flow direction.

14. A tur

Assignees

• Rolls Royce Deutschland Ltd & Co Kg
• Rolls Royce Deutschland Ltd & Co Kig

Inventors

• Guemmer Volker

Classifications

• F01D11/006 Primary

  Sealing the gap between rotor blades or blades and rotor · CPC title

• F05D2250/71

  curved · CPC title

• F01D11/08

  for sealing space between rotor blade tips and stator (specially-shaped blade tips therefor F01D5/20) · CPC title

• F05D2250/713

  inflexed · CPC title

• F01D5/143 Primary

  Contour of the outer or inner working fluid flow path wall, i.e. shroud or hub contour · CPC title