Thermal shielding in a gas turbine

Patent metadata

Field	Value
Publication number	US-10151205-B2
Application number	US-201615091933-A
Country	US
Kind code	B2
Filing date	Apr 6, 2016
Priority date	Apr 21, 2015
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

A turbine blade has a body enclosing a labyrinth of internal channels for circulation of coolant received through an inlet integrally formed in terminal portion of blade root. The labyrinth includes; inlet arranged on an axially upstream face of terminal portion leading to an upstream duct portion having first section adjacent the inlet and a second section axially downstream of first, second section having reduced cross section compared to first section. Leading edge passage intersects first section and extends through blade body towards the tip. Main blade passage intersects second section. Trailing edge passage intersects downstream duct portion which is in axial alignment with but separate from second section and channel connects second section with the downstream duct portion. Channel has reduced cross section compared to second section and downstream duct portion. The inlet has an inverted keyhole shape with cross section extends through upstream duct portion first section.

First claim

The invention claimed is:

1. A turbine blade having a body enclosing a labyrinth of internal channels for the circulation of coolant received through an inlet integrally formed in a terminal portion of the blade root, the labyrinth comprising;
the inlet arranged on an axially upstream face of the terminal portion leading to an upstream duct portion having a first section adjacent the inlet and a second section axially downstream of the first, the second section having a reduced cross section compared to the first section;
a leading edge passage intersecting the first section and extending through the blade body towards the tip of the blade;
a main blade passage intersecting the second section;
a trailing edge passage intersecting with a downstream duct portion which is in axial alignment with but separate from the second section and
a channel connecting the second section with the downstream duct portion, the channel having a reduced cross section compared to the second section and the downstream duct portion, wherein the inlet has an inverted key hole shape and the inverted key-hole cross section extends through the upstream duct portion first section.

2. A turbine blade as claimed in claim 1 wherein the channel is oval in cross section.

3. A turbine blade as claimed in claim 1 wherein the upstream duct first and second sections are distinguished by a step in the wall from the first section to the second section where the keyhole shaped section becomes a more axisymmetric cross section.

4. A turbine blade as claimed in claim 1 wherein the leading edge passage sits adjacent a wall of the leading edge of the blade and serves to cool the leading edge wall when cooling air travels through the passage.

5. A turbine blade as claimed in claim 4 wherein multiple holes are provided along or adjacent the leading edge, connecting with the leading edge passage for delivering a thin film of cooling air to an exposed surface of the leading edge.

6. A turbine blade as claimed in claim 1 wherein the main blade passage is a “multi-pass” which incorporates multiple turns in three dimensions which extend the passage between the root and tip of the blade and from a middle section of the blade body, downstream to adjacent the trailing edge of the blade.

7. A turbine blade as claimed in claim 1 wherein the trailing edge passage is adjoined to the main blade passage.

8. A turbine blade as claimed in claim 1 wherein the trailing edge passage sits adjacent a wall of the trailing edge of the blade and serves to cool the trailing edge wall when cooling air travels through the passage.

9. A turbine blade as claimed in claim 8 wherein multiple holes are provided along or adjacent the trailing edge, connecting with the trailing edge passage for delivering a thin film of cooling air to an exposed surface of the trailing edge.

10. A gas turbine engine incorporating one or more turbine blades wherein the turbine blades have the configuration as set out in claim 1 .

11. A method for making a turbine blade having the geometry of a blade according to claim 1 , the method comprising;
providing a mould defining the external geometry of the blade,
providing a core defining an internal geometry of the blade, the internal geometry comprising; an inlet arranged on an axially upstream face of a terminal portion of the blade root leading to a continuous duct terminating at a mid-blade region of the terminal portion; a leading edge passage intersecting the continuous duct portion and extending through the blade body towards the tip of the blade; a main blade passage intersecting the continuous duct portion, a trailing edge passage intersecting with a downstream duct portion, the downstream duct portion arranged in axial alignment with the continuous duct portion, but separate therefrom and terminating at a downstream end in a core breakout passage;
casting a blade between the mould and core;
removing the blade from the mould and the core from the blade;
at the inlet on the axially upstream face, machining into the continuous duct portion an upstream duct portion, the upstream duct portion having a first section adjacent the inlet and a second section downstream of the first section intersection with the leading edge passage, the inlet and first section having a cross section which is an inverted key hole shape and the second section having a reduced cross sectional area compared to the first section.

12. A method as claimed in claim 11 wherein the core further defines a channel connecting the continuous duct portion and the downstream duct portion.

13. A method as claimed in claim 12 wherein the portion of the core defining the channel is oval in cross section.

14. A method as claimed in claim 11 wherein, in a further step the core breakout passage is closed.

15. A core configured for use in the method of claim 11 , the core defining an internal geometry of a blade, the internal geometry comprising; an inlet arranged on an axially upstream face of a terminal portion of the blade root leading to a continuous duct terminating at a mid-blade region of the terminal portion; a leading edge passage intersecting the continuous duct portion and extending through the blade body towards the tip of the blade; a main blade passage intersecting the continuous duct portion, a trailing edge passage intersecting with a downstream duct portion, the downstream duct portion arranged in axial alignment with the continuous duct portion, but separate therefrom and terminating at a downstream end in a core breakout passage.

16. A method as claimed in claim 1 wherein the machining step involves plunge EDM machining using a tool which defines the geometry of the inlet, the first section and the second section.

17. A method as claimed in claim 16 wherein the tool further defines the geometry of the channel.

Assignees

• Rolls Royce Plc

Inventors

• Barry Matthew
• Burford Peter

Classifications

• Y10T29/49341

  with cooling passage · CPC title

• F01D5/186

  Film cooling (F01D5/187 takes precedence) · CPC title

• B22D25/02

  by its peculiarity of shape; of works of art {(cylinders, pistons B22D15/02)} · CPC title

• F05D2230/00

  Manufacture · CPC title

• F05D2260/202

  by film cooling · CPC title