Turbine exhaust diffusion system and method

Patent metadata

Field	Value
Publication number	US-9249687-B2
Application number	US-91372910-A
Country	US
Kind code	B2
Filing date	Oct 27, 2010
Priority date	Oct 27, 2010
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A system includes multiple blades coupled to a rotor, a stationary shroud disposed about the multiple blades, and a clearance between the stationary shroud and each blade end of the multiple blades, wherein the clearance is configured to enable over tip leakage flow. The system also includes a diffuser section that includes an outer wall defining an expanding flow path downstream from the multiple blades. The outer wall includes a first wall portion having a first angle relative to a rotational axis of the multiple blades, and the clearance is configured to enable an increase in the first angle by maintaining the boundary layer along the outer wall with the over tip leakage flow.

First claim

The invention claimed is:

1. A system, comprising:
a gas turbine engine, comprising:
a combustion section;
a turbine section coupled to the combustion section, wherein the turbine section comprises a turbine stage having a plurality of turbine blades, each blade of the plurality of turbine blades having a blade end at a first end and a second end coupled to a rotor, and a stationary shroud disposed about the plurality of turbine blades that defines a clearance between each blade end of the plurality of turbine blades and an innermost surface of the stationary shroud that is disposed at an oblique angle relative to a rotational axis of the plurality of turbine blades; and
a diffuser section coupled to the turbine section, wherein the diffuser section comprises an outer wall defining an expanding flow path downstream from the plurality of turbine blades, the outer wall comprises a first wall portion that contacts and extends from the stationary shroud, the first wall portion having a first angle relative to the rotational axis of the plurality of turbine blades, the first angle is between 16 and 40 degrees, and when over tip leakage flow flows through the clearance between each blade end and the innermost surface of the stationary shroud, the over tip leakage flow energizes and maintains a boundary layer along the outer wall.

2. The system of claim 1 , wherein the outer wall comprises a second wall portion downstream from and contacting the first wall portion, the second wall portion has a second angle relative to the rotational axis of the plurality of turbine blades, and the second angle is between 6 and 15 degrees.

3. The system of claim 2 , wherein the first angle is between 20and 30 degrees.

4. The system of claim 1 , wherein the clearance enables the over tip leakage flow to increase a radial flow velocity in the diffuser section to reduce flow separation along the outer wall.

5. The system of claim 1 , wherein the clearance is between 90 and 150 mils.

6. The system of claim 1 , wherein the diffuser section has a length and the gas turbine engine has a total length, and the length is less than 15percent of the total length.

7. A system, comprising:
a rotary section comprising a plurality of blades, each blade of the plurality of blades having a blade end at a first end and a second end coupled to a rotor, and a stationary shroud disposed about the plurality of blades that defines a clearance between each blade end of the plurality of blades and an innermost surface of the stationary shroud that is disposed at an oblique angle relative to a rotational axis of the plurality of blades; and
a diffuser section comprising an outer wall defining an expanding flow path downstream from the plurality of blades, wherein the outer wall comprises a first wall portion that contacts and extends from the stationary shroud, the first wall portion having a first angle relative to the rotational axis of the plurality of blades, the first angle is between 16 and 40 degrees, and when over tip leakage flow flows through the clearance between each blade end and the innermost surface of the stationary shroud, the over tip leakage flow energizes and maintains a boundary layer along the outer wall.

8. The system of claim 7 , wherein the rotary section comprises a turbine section.

9. The system of claim 7 , wherein the outer wall comprises a second wall portion downstream from and contacting the first wall portion, the second wall portion has a second angle relative to the rotational axis of the plurality of blades, and the second angle is between 6 and 15 degrees.

10. The system of claim 9 , wherein the first angle is between 21 and 23 degrees, the second angle is between 7 and 9 degrees.

11. The system of claim 7 , wherein, the clearance enables the over tip leakage flow to increase a radial flow velocity in the diffuser section to substantially reduce or eliminate flow separation along the outer wall.

12. A method, comprising:
enabling an over tip leakage flow to pass through a clearance between each blade end of a plurality of turbine blades of a turbine stage and an innermost surface of a stationary shroud that is disposed at an oblique angle relative to a rotational axis of the plurality of turbine blades;
radially expanding a flow from the plurality of turbine blades in a downstream direction through a first portion of a wall of a turbine diffuser that contacts and extends from the stationary shroud, the first wall portion having a first angle relative to the rotational axis of the plurality of turbine blades between 16 and 40 degrees; and
energizing and maintaining a boundary layer along the first portion of the wall of the turbine diffuser with the over tip leakage flow.

13. The method of claim 12 , wherein the first angle is between 20 and 30 degrees.

14. The method of claim 12 , comprising radially expanding the flow from the plurality of turbine blades from the first portion of the wall in the downstream direction through a second portion of the wall contacting the first wall portion and having a second angle relative to the rotational axis of the plurality of turbine blades between 6 and 15 degrees.

15. The method of claim 12 , comprising diffusing an exhaust flow from the turbine stage through the turbine diffuser over a length that is less than 15 percent of a total length of a turbine engine having the turbine stage and the turbine diffuser.

Assignees

• Nanda Deepesh D
• Cotroneo Joseph A
• Gen Electric

Inventors

• Nanda Deepesh D
• Cotroneo Joseph A

Classifications

• F01D11/08

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

• F05D2260/14

  Preswirling · CPC title

• F05D2260/60

  Fluid transfer · CPC title

• F01D25/30 Primary

  Exhaust heads, chambers, or the like · CPC title