Turbine tip clearance control method and system

Patent metadata

Field	Value
Publication number	US-10358933-B2
Application number	US-201715692619-A
Country	US
Kind code	B2
Filing date	Aug 31, 2017
Priority date	Sep 15, 2016
Publication date	Jul 23, 2019
Grant date	Jul 23, 2019

Abstract

A method of controlling a rotor tip clearance in a gas turbine engine ( 10 ). The method comprises determining an engine or component remaining useful life T r , and controlling a tip clearance control arrangement ( 38 ) to maintain a rotor tip clearance ( 36 ) at a target tip clearance D target . The target tip clearance D target is determined in accordance with a function of remaining engine life T r .

First claim

The invention claimed is:

1. A method of controlling a rotor tip clearance in a gas turbine engine, the method comprising:
determining an engine or component remaining useful life T r ;
predicting a current rotor tip clearance; and
controlling a tip clearance control arrangement to maintain the predicted current rotor tip clearance at a target tip clearance D target , wherein
the target tip clearance D target is determined in accordance with a function of remaining engine life T r , and the target tip clearance D target is periodically updated over a life of the engine in accordance with the function of remaining engine life T r .

2. A method according to claim 1 , wherein the step of determining the target tip clearance D target further comprises:
a. determining a nominal remaining life fuel burn change ΔFB reduced associated with a reduced tip clearance D reduced ;
b. determining a tip rub probability P rub associated with the reduced tip clearance D reduced ;
c. determining a remaining life fuel burn change ΔFB rub associated with a tip rub;
d. determining a risk adjusted remaining life fuel burn FB adjusted for the reduced tip clearance; and
e. where the risk adjusted remaining engine life fuel burn change ΔFB adjusted is less than zero, setting the target tip clearance D target to the reduced tip clearance D reduced .

3. A method according to claim 2 , wherein the step of determining the target tip clearance D target further comprises:
predicting an abradable liner thickness at the expiry of the remaining useful life T r where the engine is operated at the reduced tip clearance D reduced , and setting the target tip clearance D target at the reduced tip clearance D target only where the predicted abradable liner thickness at the expiry of the remaining useful life exceeds a minimum threshold.

4. A method according to claim 1 , wherein the rotor comprises one of a turbine rotor and a compressor.

5. A method according to claim 1 , wherein the remaining engine life comprises one or more of a number of flight hours prior to the next engine overhaul, and a number of flight cycles prior to the next engine overhaul.

6. A gas turbine engine rotor tip clearance control apparatus comprising a tip clearance controller configured to (1) predict a current rotor tip clearance and (2) maintain the predicted current tip clearance at a target tip clearance D target , the target tip clearance being determined in accordance with a function of remaining engine life T r , and the target tip clearance D target being updated over a life of the engine in accordance with the function of remaining engine life T r .

Assignees

• Rolls Royce Plc

Inventors

• Moxon Matthew

Classifications

• F04D27/001

  Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring · CPC title

• F01D17/145

  by means of valves, e.g. for steam turbines (valves in general F16K) · CPC title

• F05D2260/82

  Forecasts · CPC title

• F05D2270/30

  Control parameters, e.g. input parameters · CPC title

• F04D27/002

  by varying geometry within the pumps, e.g. by adjusting vanes · CPC title