Gas turbine engine control system having integral flight Mach number synthesis method

Claim 2

For an aircraft installed gas turbine engine having a compressor driven by a high pressure turbine and a thrust producing fan driven by a low pressure turbine, a control system of said engine for modulating engine thrust based on an aircraft flight Mach number (Mn) value computed in said control system comprising: means for measuring a first operating parameter of said engine; means for generating a system ratio parameter based on said first operating parameter according to a predetermined engine schedule; means for measuring a second operating parameter of said engine; means for dividing said second operating parameter by said system ratio parameter to yield a calculated first quotient; means for measuring a third operating parameter of said engine; means for dividing said first quotient by said third operating parameter to yield a calculated second quotient; means for generating an aircraft Mn value based on said second quotient according to a predetermined relationship; and means for utilizing said aircraft Mn value in a power management module of said engine control to regulate said first operating parameter to produce a predetermined thrust value.

Claim 3

For an aircraft installed gas turbine engine having a compressor driven by a high pressure turbine and a thrust producing fan driven by a low pressure turbine, a method of modulating engine thrust based on an aircraft flight Mach number (Mn) value computed in a control of said engine, comprising the steps of: measuring a first operating parameter of said engine; generating a system ratio parameter based on said first operating parameter according to a predetermined engine schedule; measuring a second operating parameter of said engine; dividing said second operating parameter by said system ratio parameter to yield a calculated first quotient; measuring a third operating parameter of said engine; dividing said first quotient by said third operating parameter to yield a calculated second quotient; generating an aircraft Mn value based on said second quotient according to a predetermined relationship; and utilizing said aircraft Mn value in a power management module of said engine control to regulate said first operating parameter to produce a predetermined thrust value.

Claim 4

For an aircraft installed gas turbine engine having a compressor driven by a high pressure turbine and a thrust producing fan driven by a low pressure turbine, a method of modulating engine thrust based on an aircraft flight Mach number (Mn) value computed in a control of said engine, comprising the steps of: measuring a first operating parameter of said engine; generating a system ratio parameter based on said first operating parameter according to a predetermined engine schedule; measuring a second operating parameter of said engine; dividing said second operating parameter by said system ratio parameter to yield a calculated first quotient; measuring a third operating parameter of said engine; dividing said first quotient by said third operating parameter to yield a calculated second quotient; generating an aircraft Mn value based on said second quotient according to a predetermined relationship; and utilizing said aircraft Mn value in a power management module of said engine control to regulate said first operating parameter to produce a predetermined thrust value.

Claim 5

For an aircraft installed gas turbine engine having a compressor driven by a high pressure turbine and a thrust producing fan driven by a low pressure turbine, a method of modulating engine thrust based on an aircraft flight Mach number (Mn) value computed in a control of said engine, comprising the steps of: measuring a first operating parmameter of said engine; measuring a second operating parameter of said engine; generating a first correction factor based on said second operating parameter according to a first predetermined relationship; multiplying said first operating parameter by said correction factor to produce a first corrected operating parameter; generating a system ratio parameter based on said first corrected operating parameter according to a predetermined engine schedule; measuring a third operating parameter of said engine; dividing said third operating parameter by said system ratio parameter to yield a calculated first quotient; measuring a fourth operating parameter of said engine; dividing said first quotient by said fourth operating parameter to yield a calculated second quotient; generating an aircraft Mn value based on said second quotient according to a second predetermined relationship; and utilizing said aircraft Mn value in a power management module of said engine control to regulate said first corrected operating parameter to produce a predetermined thrust value.

Claim 6

For an aircraft installed gas turbine engine having a compressor driven by a high pressure turbine and a thrust producing fan driven by a low pressure turbine, a method of modulating engine thrust based on an aircraft flight Mach number (Mn) value computed in a control of said engine, comprising the steps of: measuring a first operating parmameter of said engine; measuring a second operating parameter of said engine; generating a first correction factor based on said second operating parameter according to a first predetermined relationship; multiplying said first operating parameter by said correction factor to produce a first corrected operating parameter; generating a system ratio parameter based on said first corrected operating parameter according to a predetermined engine schedule; measuring a third operating parameter of said engine; dividing said third operating parameter by said system ratio parameter to yield a calculated first quotient; measuring a fourth operating parameter of said engine; dividing said first quotient by said fourth operating parameter to yield a calculated second quotient; generating an aircraft Mn value based on said second quotient according to a second predetermined relationship; and utilizing said aircraft Mn value in a power management module of said engine control to regulate said first corrected operating parameter to produce a predetermined thrust value.

Claim 7

The method according to claim 3 wherein the system ratio parameter generating step includes: generating a modeled system ratio parameter based on said first corrected operating parameter according to said predetermined engine schedule; and multiplying said modeled system ratio parameter by at least a first scalar value, wherein said first scalar value is a function of said first corrected operating parameter.

Claim 8

The method according to claim 4 wherein the system ratio parameter generating step further includes: multiplying said modeled system ratio parameter by at least a second scalar value, wherein said second scalar value is equal to unity for a first operating condition of said engine and is a function of said first corrected operating parameter for a second operating condition of said engine.

Claim 9

The method according to claim 5 wherein: said first operating parameter comprises fan speed, N1; said second operating parameter comprises inlet temperature, T1; said third operating parameter comprises compressor discharge pressure, PS3; said fourth operating parameter comprises ambient pressure, P0; said first corrected operating parameter comprises corrected fan speed, N1R; said system ratio parameter comprises a ratio of compressor discharge pressure, PS3, to inlet pressure, P1; said first quotient comprises inlet pressure, P1; and said second quotient comprises a ratio of inlet pressure, P1, to ambient pressure, P0.

Claim 10

The method according to claim 6 wherein said second predetermined relationship between said aircraft Mn value and said second quotient comprises a compressible flow relationship.

Claim 11

The method according to claim 6 wherein said first predetermined relationship between said inlet temperature, T1, and said first correction factor comprises a mathematical normalization producing said first correction factor used to convert measured fan speed, N1, to corrected fan speed, N1R.

Claim 12

The method according to claim 6 wherein the ambient pressure, P0, measurement step includes: measuring an ambient pressure sensor output, P0s; generating a second correction factor based on a previously calculated Mn value according to a third predetermined relationship; and multiplying said sensor output, P0s, by said second correction factor to yield said ambient pressure, P0.

Claim 13

The method according to claim 5 wherein: said second scalar value comprises a product of a plurality of additional discrete scalar values related to selectable bleed airflow from said compressor whereby: said second scalar value is equal to unity when bleed airflow is not selected; and said second scalar value is a function of said first corrected operating parameter when bleed airflow is selected.