Turboshaft

Patent metadata

Field	Value
Publication number	US-2021222617-A1
Application number	US-202017060986-A
Country	US
Kind code	A1
Filing date	Oct 1, 2020
Priority date	Oct 23, 2019
Publication date	Jul 22, 2021
Grant date	—

Abstract

A turboshaft gas turbine engine comprises, in fluid flow series, a gas-generator compressor, a combustor, a gas-generator turbine, and a free power turbine. The expansion ratios of the turbines are dependent upon an outlet temperature of the combustor, and an expansion relationship between the turbines is defined as the ratio of expansion ratios of the turbines over a running range of non-dimensional power outputs of the gas turbine engine. A second derivative of the expansion relationship is from 0.6 to 1.0.

First claim

1 . A turboshaft gas turbine engine comprising, in fluid flow series, a gas-generator compressor, a combustor, a gas-generator turbine, and a free power turbine;
wherein the expansion ratios of the turbines are dependent upon an outlet temperature of the combustor, and an expansion relationship between the turbines is defined as the ratio of expansion ratios of the turbines over a running range of non-dimensional power outputs of the gas turbine engine; wherein a second derivative of the expansion relationship is from 0.6 to 1.0.

2 . The gas turbine engine of claim 1 , wherein a second derivative of the expansion relationship is from 0.7 to 0.9.

3 . The gas turbine engine of claim 1 , wherein:
the gas-generator turbine is a single-stage turbine; and the free power turbine a single stage turbine.

4 . The gas turbine engine of claim 3 , wherein a ratio of a turbine blade stress parameter (AN 2 ) of the gas-generator turbine to the turbine blade stress parameter of the free power turbine is from 0.7 to 2.3.

5 . The gas turbine engine of claim 4 , wherein said ratio of the turbine blade stress parameters is from 0.8 to 1.7.

6 . The gas turbine engine of claim 3 , wherein a ratio of a turbine disc stress parameter (U/√T) of the gas-generator turbine to the turbine disc stress parameter of the free power turbine is from 1 to 1.7.

7 . The gas turbine engine of claim 6 , wherein said ratio of the turbine disc stress parameters is from 1.3 to 1.4.

8 . The gas turbine engine of claim 1 , wherein:
the gas-generator turbine is a single-stage turbine; and the free power turbine is a two-stage turbine.

9 . The gas turbine engine of claim 8 , in which a ratio of the stress parameter (AN 2 ) of the gas-generator turbine to the stress parameter of the first stage of the free power turbine is from 0.54 to 1.4.

10 . The gas turbine engine of claim 8 , in which a ratio of the stress parameter (AN 2 ) of the gas-generator turbine to the stress parameter of the second stage of the free power turbine is from 0.62 to 1.

11 . The gas turbine engine of claim 8 , in which a ratio of a turbine disc stress parameter (U/√T) of the gas-generator turbine to the turbine disc stress parameter of the second stage of the free power turbine is from 0.92 to 1.5.

12 . The gas turbine engine of claim 8 , in which said ratio of a turbine disc stress parameters is from 1.1 to 1.22.

13 . The gas turbine engine of claim 8 , in which the gas-generator turbine comprises a stator having from 14 to 30 nozzle guide vanes.

14 . The gas turbine engine of claim 8 , in which the gas-generator turbine comprises a rotor having from 30 to 60 turbine blades.

15 . The gas turbine engine of claim 8 , in which a ratio of the number of nozzle guide vanes in the stator to the number of turbine blades in the rotor is from 0.23 to 1.

16 . The gas turbine of claim 1 , in which the gas-generator turbine and the free power turbine are arranged to contra-rotate.

Assignees

• Rolls Royce Plc
• Rolls Royce Deutschland Ltd & Co Kg

Inventors

• Stieger Rory D
• Taylor Mark D
• Janke Erik

Classifications

• F02C7/36

  Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user ({F02C3/107 - F02C3/13 and} F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H) · CPC title

• F02C3/10 Primary

  with another turbine driving an output shaft but not driving the compressor · CPC title

• F02C3/103 Primary

  the compressor being of the centrifugal type · CPC title

• F02C7/32

  Arrangement, mounting, or driving, of auxiliaries · CPC title

• F05D2240/35

  Combustors or associated equipment · CPC title