Surge detection system using engine signature
First Claim
1. A method of detecting an occurrence of a surge in a gas turbine engine, comprising the steps of:
- during individual ones of a plurality of consecutively occurring time periods during an operation of a gas turbine engine,operating a first transducer to generate a first electrical signal for representing a first engine operating characteristic;
processing the first electrical signal to obtain a derivative of the first engine operating characteristic;
operating a second transducer to generate a second electrical signal for representing a second engine operating characteristic;
processing the second electrical signal to obtain a derivative of the second engine operating characteristic;
comparing the derivative of the first engine operating characteristic to a first threshold value;
comparing the derivative of the second engine operating characteristic to a second threshold value;
incrementing a counter by a predetermined value only if the derivative of the first engine operating characteristic exceeds the first threshold value and if the derivative of the second engine operating characteristic exceeds the second threshold value;
else, if at least one of the first and second threshold values is not exceeded,decrementing the counter by the predetermined value; and
generating an output electrical signal for indicating an occurrence of a surge condition only if a value of the counter is equal to a predetermined value.
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Accused Products
Abstract
A method of, and a system for, detecting an occurrence of a surge in a gas turbine engine. The method includes steps, executed during consecutively occurring time periods, of: obtaining filtered derivatives of first and second engine operating characteristics; comparing the filtered derivatives of the first and the second engine operating characteristics to first and second threshold values, respectively; and incrementing a count only if both of the filtered derivatives exceed their respective threshold values. Otherwise, a next step decrements the count if one or both of the filtered derivatives do not exceed their respective threshold values. The method further includes a step of indicating a surge condition only if the count is equal to a predetermined value that is greater than unity. In a presently preferred embodiment of this invention the engine is a turbofan engine, the first engine operating characteristic is fan speed, and the second engine operating characteristic is exhaust gas temperature.
76 Citations
21 Claims
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1. A method of detecting an occurrence of a surge in a gas turbine engine, comprising the steps of:
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during individual ones of a plurality of consecutively occurring time periods during an operation of a gas turbine engine, operating a first transducer to generate a first electrical signal for representing a first engine operating characteristic;
processing the first electrical signal to obtain a derivative of the first engine operating characteristic;operating a second transducer to generate a second electrical signal for representing a second engine operating characteristic; processing the second electrical signal to obtain a derivative of the second engine operating characteristic; comparing the derivative of the first engine operating characteristic to a first threshold value; comparing the derivative of the second engine operating characteristic to a second threshold value; incrementing a counter by a predetermined value only if the derivative of the first engine operating characteristic exceeds the first threshold value and if the derivative of the second engine operating characteristic exceeds the second threshold value;
else, if at least one of the first and second threshold values is not exceeded,decrementing the counter by the predetermined value; and generating an output electrical signal for indicating an occurrence of a surge condition only if a value of the counter is equal to a predetermined value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for detecting a surge in a gas turbine engine, comprising:
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first means, having an input coupled to a first electrical signal and operating during individual ones of a plurality of consecutively occurring time periods, for determining a derivative of a first engine operating characteristic from the first electrical signal; second means, having an input coupled to a second electrical signal and operating during individual ones of the plurality of consecutively occurring time periods, for determining a derivative of a second engine operating characteristic from the second electrical signal; first means, having an input coupled to an output of said first determining means, for comparing the derivative of the first engine operating characteristic to a first threshold value; second means, having an input coupled to an output of said second determining means, for comparing the derivative of the second engine operating characteristic to a second threshold value; a counter including means, having inputs coupled to an output of each of said first and second comparing means, for incrementing a count of said counter only if said output of said first comparing means indicates that the derivative of the first engine operating characteristic exceeds the first threshold value and if said output of said second comparing means indicates that the derivative of the second engine operating characteristic exceeds the second threshold value; said counter further including means for decrementing the count if at least one of said output of said first comparing means indicates that the derivative of the first engine operating characteristic does not exceed the first threshold value and if said output of said second comparing means indicates that the derivative of the second engine operating characteristic does not exceed the second threshold value; and means, having an input coupled to an output of said counter, for generating an output signal for indicating a surge condition in response to the count being equal to a predetermined value that is greater than unity. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A system for detecting a surge in a gas turbine fan engine having a rotating fan and a combustor generating an exhaust gas, comprising:
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first means, having an input coupled to a first electrical signal and operating during individual ones of a plurality of consecutively occurring time periods, for determining a derivative of a speed of rotation of the fan from the first electrical signal; second means, having an input coupled to a second electrical signal and operating during individual ones of the plurality of consecutively occurring time periods, for determining a derivative of a temperature of the exhaust gas from the second electrical signal; first filter means having an input coupled to an output of said first determining means for filtering the derivative of the speed of rotation of the fan; second filter means having an input coupled to an output of said second determining means for filtering the derivative of the temperature of the exhaust gas; first comparing means having an input coupled to an output of said first filtering means for comparing the filtered derivative of the fan speed to a first threshold value; second comparing means having an input coupled to an output of said second filtering means for comparing the derivative of the temperature of the exhaust gas to a second threshold value; a counter including means, having inputs coupled to an output of each of said first and second comparing means, for incrementing a count of said counter only if said output of said first comparing means indicates that the filtered derivative of the fan speed exceeds the first threshold value and if said output of said second comparing means indicates that the filtered derivative of the temperature of the exhaust gas exceeds the second threshold value; said counter further including means for decrementing the count if the count is not already zero and if at least one of said output of said first comparing means indicates that the filtered derivative of the fan speed does not exceed the first threshold value and if said output of said second comparing means indicates that the filtered derivative of the temperature of the exhaust gas does not exceed the second threshold value; and means, having an input coupled to an output of said counter, for generating an output signal for indicating a surge condition in response to the count being equal to a predetermined value that is greater than unity. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method of operating a fuel control system for a gas turbine engine, comprising the steps of:
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when operating in a manual mode of operation and, during individual ones of a plurality of consecutively occurring time periods, (a) obtaining a filtered derivative of a first engine operating characteristic; (b) obtaining a filtered derivative of a second engine operating characteristic; (c) comparing the filtered derivative of the first engine operating characteristic to a first threshold value; (d) comparing the filtered derivative of the second engine operating characteristic to a second threshold value; (e) incrementing a counter only if the filtered derivative of the first engine operating characteristic exceeds the first threshold value and if the filtered derivative of the second engine operating characteristic exceeds the second threshold value;
else(f) decrementing the counter; and (g) periodically updating a value of filter parameters used in obtaining the filtered derivatives; in response to an input electrical signal that indicates a change from the manual mode of operation to an automatic mode of operation, the method further includes the steps of; resetting the counter; continuing to execute steps (a) through (g) during individual ones of the plurality of consecutively occurring time periods, wherein initially the value of the filter parameters is a function of the engine operation during the manual mode of operation; and indicating an occurrence of an engine surge condition only if a value of the counter is equal to a predetermined value that is greater than unity.
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Specification