Method and system of controlling a jet engine for avoiding engine surge
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorGary J. Haloff
Life of this patent
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Abstract
A jet engine is controlled by placing time variant total pressure probes at the entry plane and the discharge plane of a jet engine fan. The pressure values at the probes are converted into electrical signals, filtered, and then fed to meters where the root-mean-square (RMS) values of the electrical signals are determined. The RMS values are fed to a computer which computes the ratio of the two RMS values and this ratio is fed to a comparison circuit which generates a difference signal representing the difference between the RMS ratio and a predetermined limit value. If the RMS ratio equals the limit value, then the operating point of a fan is altered by either changing the nozzle area, changing the fan speed, or changing the altitude or Mach number.
Claims7
A system for automatically avoiding a surge of a jet engine having a fan with an entry plane and a discharge plane, comprising:
- a. a first time variant total pressure probe positioned at the entry plane of the jet engine fan;
- b. a second time variant total pressure probe positioned at the discharge plane of the jet engine fan;
- c. first and second means for converting responses of the first and second pressure probes respectively into corresponding electrical signals;
- d. first and second RMS meters fed respectively by the first and second converting means;
- e. a computer fed by the first and second RMS meters for determining the ratio of the outputs of second RMS meter to the first RMS meter;
- f. a threshold circuit fed by the computer wherein the ratio of the outputs of the first and second RMS meters is compared with a predetermined limit value;
- and
- g. means for controlling the operating point of the fan.
Dependencies are inferred from the claim text.