US 6,292,763 B1Granted

Methods for designing variable cycle gas turbine engines

AssigneeDiversitech Corporation

InventorsDonald K. Dunbar, Marlen L. Miller, George L. Converse

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Abstract

A method for designing a variable cycle gas turbine engine having a fan assembly with a maximum air flow there through and a maximum pressure ratio there across during operation at a fan speed and a plurality of variable pitch vanes, which method includes the steps of selecting a first operating point of the variable cycle gas turbine engine at a fan speed having about maximum air flow through the fan assembly at a pressure ratio substantially less than maximum pressure ratio and selecting a second operating point of the variable cycle gas turbine engine at about the fan speed, wherein the second operating point has about the maximum pressure ratio across the fan assembly at an air flow through the fan assembly substantially less than the maximum air flow. A reference point having a reference air flow through the fan assembly and a reference pressure ratio across the fan assembly is selected. The geometry of the variable pitch vanes is determined so that the variable pitch vanes can operate at the reference point without stalling.

Claims18

Dependent claims

A method for designing a variable cycle gas turbine engine, said variable cycle gas turbine engine having a fan assembly with a maximum air flow there through and a maximum pressure ratio there across during operation at a fan speed, said fan assembly having a plurality of variable pitch vanes, comprising the steps of:

(a) selecting a first operating point of the variable cycle gas turbine engine at a fan speed having about said maximum air flow through said fan assembly at a pressure ratio substantially less than said maximum pressure ratio;
(b) selecting a second operating point of the variable cycle gas turbine engine at about said fan speed, said second operating point having about said maximum pressure ratio across said fan assembly at an air flow through said fan assembly substantially less than said maximum air flow;
(c) selecting a reference point having a reference air flow through said fan assembly and a reference pressure ratio across said fan assembly;
(d) determining a geometry of said variable pitch vanes such that said variable pitch vanes can operate at said reference point without stalling;
(e) determining whether said variable pitch vanes stall at said second operating point and repeating steps (c) and (d) until said variable pitch vanes do not stall at said second operating point;
(f) determining an efficiency of said fan assembly at said first operating point and repeating steps (c) to (e) until said efficiency is at least about equal to a predetermined efficiency;
and
(g) employing the variable pitch vane geometry from step (d) for design of said variable cycle gas turbine engine.

5 more elements

(a) selecting a first operating point of the variable cycle gas turbine engine at a fan speed having about said maximum air flow through said fan assembly at a pressure ratio substantially less than said maximum pressure ratio;
(b) selecting a second operating point of the variable cycle gas turbine engine at about said fan speed, said second operating point having about said maximum pressure ratio across said fan assembly at an air flow through said fan assembly substantially less than said maximum air flow;
(c) selecting a reference point having a reference air flow through said fan assembly and a reference pressure ratio across said fan assembly, wherein said reference air flow is between about said maximum air flow and about said air flow of said second operating point and wherein said reference pressure ratio is between about said maximum pressure ratio and about said pressure ratio of said second operating point;
(d) determining a geometry of said variable pitch vanes such that said variable pitch vanes can operate at said reference point without stalling;
(e) determining whether said variable pitch vanes stall at said second operating point and repeating steps (c) and (d) until said variable pitch vanes do not stall at said second operating point;
(f) determining an efficiency of said fan assembly at said first operating point and repeating steps (c) to (e) until said efficiency is at least about equal to a predetermined efficiency;
and
(g) employing the variable pitch vane geometry from step (d) for design of said variable cycle gas turbine engine.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/133,293Filed 12 Aug 1998 · division
Priority: 27 Aug 1996
Granted: 18 Sep 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

F04D 29/563
Adjustable: specially adapted for elastic fluid pumps
F01D 17/162
By means of nozzle vanes: for axial flow, i.e. the vanes turning around axes which are essentially perpendicular to the rotor centre line
F02C 3/067
The compressor comprising only axial stages: having counter-rotating rotors
F02K 1/16
Control or regulation: conjointly with another control