Thermal shielding in a gas turbine

Patent metadata

Field	Value
Publication number	US-10408063-B2
Application number	US-201615084651-A
Country	US
Kind code	B2
Filing date	Mar 30, 2016
Priority date	Apr 21, 2015
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

A turbine blade having a labyrinth of internal channels for circulation of coolant received through an inlet formed in a terminal portion of a blade root. A labyrinth geometry includes: (i) 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 having a reduced cross-section compared to the first section, (ii) a leading edge passage intersecting with the first section and extending through a blade body towards a tip of the blade, where a proximal end of the leading edge passage is angled towards a direction of incoming air flow, (iii) a main blade passage intersecting with a downstream duct portion arranged in axial alignment with, and separate from, the upstream duct portion, and (iv) a restrictor passage intersecting with a mid-blade passage and extending towards a mid-blade duct portion.

First claim

The invention claimed is:

1. A turbine blade having a labyrinth of internal channels for circulation of a coolant, the labyrinth comprising:
an inlet integrally formed in a terminal portion of a blade root of the blade, the inlet being arranged on an axially upstream face of the terminal portion leading to an upstream duct portion having a first section adjacent to the inlet and a second section, the second section having a reduced cross section compared to the first section;
a leading edge passage intersecting with the first section and extending through a blade body of the blade towards a tip of the blade, a proximal end of the leading edge passage being angled, in use, towards a direction of incoming air flow;
a main blade passage intersecting with a downstream duct portion, the downstream duct portion being arranged in axial alignment with the upstream duct portion and being separate from the upstream duct portion; and
a restrictor passage intersecting with the main blade passage and extending towards a mid-blade duct portion, the mid-blade duct portion being in axial alignment with the upstream duct portion and the downstream duct portion, and the mid-blade duct portion being in fluid communication with the upstream duct portion.

2. The turbine blade as claimed in claim 1 , further comprising a plurality of holes arranged on the blade body and connecting with one of the leading edge passage and the main blade passage to deliver a thin film of cooling air to an exposed surface of the blade.

3. The turbine blade as claimed in claim 1 , wherein the main blade passage is a multi-pass passage incorporating multiple turns in three dimensions, which extends the main blade passage from between the blade root and the tip of the blade and from a middle section of the blade body, and continuing downstream to adjacent to a trailing edge of the blade.

4. The turbine blade as claimed in claim 1 , wherein the mid-blade duct portion has a smaller cross section in an axially facing direction than the upstream duct portion.

5. The turbine blade as claimed in claim 1 , wherein the restrictor passage is relatively narrow compared to the main blade passage and the leading edge passage where the main blade passage intersects the downstream duct portion and where the leading edge passage intersects the upstream duct portion.

6. The turbine blade as claimed in claim 1 , which has been cast around a removable core, the core defining at least part of the labyrinth of channels.

7. The turbine blade as claimed in claim 6 , further comprising a core breakout exit exiting a downstream face of the terminal portion.

8. The turbine blade as claimed in claim 7 , further comprising a recess formed in the downstream face and around the core breakout exit and a plate secured in the recess to close the core breakout exit.

9. The turbine blade as claimed in claim 7 , further including a slot in a terminal face of the terminal portion extending through the terminal portion and across the core breakout exit and a plate secured in the slot to obstruct the core breakout exit and close off the core breakout exit.

10. The turbine blade as claimed in claim 7 , further including a seal plate having a location lug sized to fit the core breakout exit, the seal plate extending past the terminal face of the root to cover an interface of the blade root with a recess in a turbine disc reducing leakage of cooling air in a region of the interface.

11. The turbine blade as claimed in claim 1 , further comprising an additional channel extending through a downstream wall of the mid-blade duct portion through to an upstream wall of the downstream duct portion to provide a second route to deliver coolant to the main blade passage via the downstream duct portion.

12. The turbine blade as claimed in claim 1 , further comprising a feed channel extending from the main blade passage and exiting at a downstream face of the terminal portion to feed cooling air to a supply for cooling an adjacent turbine disc.

13. The turbine blade as claimed in claim 1 , wherein a height of the mid-blade duct portion in a direction extending along a root-to-tip axis of the blade is between 0.6 and 0.7 times a height of the upstream duct portion.

14. The turbine blade as claimed in claim 1 , wherein the mid-blade duct portion and an intersection of the mid-blade duct portion with the restrictor passage have a downstream wall positioned at a depth of about 50-70% of the blade root in an upstream-to-downstream axial direction.

15. The turbine blade as claimed in claim 1 , wherein the restrictor passage has a linear axis which extends in a root-to-tip direction of the blade and the main blade passage, the restrictor passage intersecting with the main blade passage adjacent to a bend in the main blade passage where the main blade passage turns from a downstream position, in which the main blade passage intersects with the downstream duct portion, to a central position between an upstream wall and a downstream wall of the blade root.

16. A method for making the turbine blade having the labyrinth of internal channels in accordance with claim 1 , the method comprising;
providing a mould defining an external geometry of the blade;
providing a core defining the internal geometry of the blade, the internal geometry defining the labyrinth of the internal channels of the blade;
casting the blade between the mould and the core;
removing the blade from the mould and the core; and
at the inlet on the axially upstream face, machining the upstream duct portion into an upstream region of a continuous duct portion, the upstream duct portion having the first section adjacent to the inlet and the second section downstream of the first section, where the second section has the reduced cross section as compared to the first section.

Assignees

• Rolls Royce Plc

Inventors

• Diamond Stephen Christopher

Classifications

• F05D2260/20

  Heat transfer, e.g. cooling · CPC title

• B22D15/02

  of cylinders, pistons, bearing shells or like thin-walled objects · CPC title

• Y10T29/49341

  with cooling passage · CPC title

• B23P15/02

  turbine or like blades from one piece · CPC title

• F01D5/188

  with an insert in the blade cavity to guide the cooling fluid, e.g. forming a separation wall · CPC title