Gas turbine engine geometry control

• US 3,981,140 A
• Filed: 06/23/1975
• Issued: 09/21/1976
• Est. Priority Date: 06/23/1975
• Status: Expired due to Term

• Current Assignee: Allison Engine Company, Inc. (Rolls-Royce Holdings Plc)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Schroff, Dennis E., Lunsford, Jimmy L., Steffey, David R.
• Primary Examiner(s): Gordon, Clarence R.
• Application Number:
  US05/589,470
• Time in Patent Office: 456 Days
• Field of Search: 60/39.03, 60/39.2, 60/39.24, 60/39.25, 60/39.27, 60/39.29, 415/29, 415/149, 415/159, 415/162
• US Class Current: 60/773
• CPC Class Codes: F01D 17/165 for radial flow, i.e. the vanes turning around axes which are essentially parallel to the rotor centre line F01D17/167 takes precedence
• CPC Class Codes: F02C 9/22 by adjusting turbine vanes

Abstract

A single-shaft gas turbine engine suited for road vehicle propulsion has variable inlet and outlet guide vanes in the compressor of the engine and a variable turbine nozzle. These variable features are called engine variable goemetry (EVG). In normal operation, the areas of the flow paths at the inlet and outlet of the compressor and of the turbine nozzle are varied with desired power level to suit varying air flow through the engine. An actuator increases the areas in response to a request for increased power output.

In a braking mode, the compressor variable geometry is decoupled from the actuator and remains at a minimum flow condition while the turbine nozzle is opened as the power request decreases below a particular low value. The opening of the turbine nozzle decreases the engine power output, thus increasing its capacity to absorb power from the vehicle. Logic circuits control the coupling and decoupling of the compressor variable geometry.

Claims

1. A method of operating a gas turbine engine including a compressor, combustion apparatus, and a turbine driving the compressor, and having variable compressor and turbine geometry, the method comprising

varying concurrently the flow areas through the compressor and the turbine as a function of engine power level request in normal load-powering operation of the engine to vary the flow capacity of the engine

and closing the compressor variable geometry while opening the turbine variable geometry to spoil the power output of the engine for load-braking operation of the engine.

2. A gas turbine engine comprising, in combination, a compressor, combustion apparatus supplied by the compressor, and a turbine supplied by the combustion apparatus and connected to drive the compressor and a load;

the compressor including variable configuration vane means operable to adapt the compressor to varying air flow rates;

the turbine including variable area nozzle means;

actuating means connected to the two said variable means for concurrently adjusting them to match compressor and turbine characteristics through a range of engine power output levels;

coupling means operable to decouple the compressor variable means from the said actuating means so that the actuating means is free to adjust the turbine nozzle means without moving the compressor variable means;

means effective to maintain the compressor variable means in a low air flow condition when it is decoupled from the actuating means; and

means effective to open the turbine nozzle while the compressor variable means is in a low air flow condition for load braking operation of the engine.

3. A gas turbine engine comprising, in combination, a compressor, combustion apparatus supplied by the compressor, and a turbine supplied by the combustion apparatus and connected to drive the compressor and a load;

the compressor including variable configuration vane means operable to adapt the compressor to varying air flow rates;

the turbine including variable area nozzle means;

actuating means connected to the two said variable means for concurrently adjusting them to match compressor and turbine characteristics through a range of engine power output levels;

coupling means operable to decouple the compressor variable means from the said actuating means so that the actuating means is free to adjust the turbine nozzle means without moving the compressor variable means;

means effective to maintain the compressor variable means in a low air flow condition when it is decoupled from the actuating means;

means effective to control the actuating means and the coupling means including means for transmitting an engine power request signal;

means responsive to the power request signal for generating a nozzle area signal varying from high area at minimum power request to minimum area at a predetermined low power request level and then increasing area with increasing power request; and

means responsive to existence of both a power request below the said level and a low air flow condition of the compressor variable means effective to disengage the coupling means.

4. A gas turbine engine comprising, in combination, a compressor, combustion apparatus supplied by the compressor, and a turbine by the combustion apparatus and connected to drive the compressor and a load;

the compressor including variable configuration vane means operable to adapt the compressor to varying air flow rates;

the turbine including variable area nozzle means;

actuating means connected to the two said variable means for concurrently adjusting them to match compressor and turbine characteristics through a range of engine power output levels;

coupling means operable to decouple the compressor variable means from the said actuating means so that the actuating means is free to adjust the turbine nozzle means without moving the compressor variable means;

means effective to maintain the compressor variable means in a low air flow condition when it is decoupled from the actuating means;

means effective to control the actuating means and the coupling means including means for transmitting an engine power request signal;

means responsive to the power request signal for generating a nozzle area signal varying from high area at minimum power request to minimum area at a predetermined low power request level and then increasing area with increasing power request;

means responsive to a power request below the said level effective to disengage the coupling means; and

means responsive to a power request above the said level effective to engage the coupling means.

5. A gas turbine engine comprising, in combination, a compressor, combustion apparatus supplied by the compressor, and a turbine supplied by the combustion apparatus and connected to drive the compressor and a load;

the compressor including variable configuration vane means operable to adapt the compressor to varying air flow rates;

the turbine including variable area nozzle means;

actuating means connected to the two said variable means for concurrently adjusting them to match compressor and turbine characteristics through a range of engine power output levels;

coupling means operable to decouple the compressor variable means from the said actuating means so that the actuating means is free to adjust the turbine nozzle means without moving the compressor variable means;

means effective to maintain the compressor variable means in a low air flow condition when it is decoupled from the actuating means;

means effective to control the actuating means and the coupling means including means for transmitting an engine power request signal;

means responsive to the power request signal for generating a nozzle area signal varying from high area at minimum power request to minimum area at a predetermined low power request level and then increasing area with increasing power request;

means responsive to existence of both a power request below the said level and a low air flow condition of the compressor variable means effective to disengage the coupling means;

means responsive to existence of both a power request above the said level and a disengaged condition of the coupling means to transmit a minimum nozzle area signal to the actuating means; and

means responsive to existence of both a power request above the said level and a minimum nozzle area condition effective to engage the coupling means.

6. A gas turbine engine comprising, in combination, a compressor, combustion apparatus supplied by the compressor, and a turbine supplied by the combustion apparatus and connected to drive the compressor and a load;

the compressor including variable inlet configuration means and variable outlet configuration means to adapt to varying air flow rates;

the turbine including a nozzle means variable through two ranges of configuration, a first range to adapt to varying flow rates and a second range including a setting effective for load braking;

drive means connected to the three said variable means for concurrently adjusting the three to match compressor and turbine characteristics through the first said range of turbine configuration; and

means operative to disengage the compressor variable means from the said drive means so that the drive means is free to move the nozzle means to the said setting without further moving the compressor variable means.