Control for gas turbine engine
AssigneeUnited Technologies Corporation
InventorWalter B. Kerr
Life of this patent
Estimating the term…
Abstract
Increased thrust during the transonic flight mode of an aircraft powered by a gas turbine engine is realized by a closed loop control that closes the loop on the pressure ratio across the fan by adjusting fuel flow and/or exhaust nozzle area in a turbofan, variable exhaust nozzle installation. Fan pressure ratio is scheduled as a function of corrected fan speed and actual pressure ratio provides an error signal to readjust engine operation to null out this error signal. A turbine inlet temperature limit signal is generated to prevent inadvertent overheating and it or this pressure ratio error signal is selected for providing the lower fuel flow value.
Claims9
Control means for controlling a twin-spool gas turbine engine during a subsonic or transonic flight mode having variable area exhaust nozzle powering aircraft, said twin spool including a fan driven by a low turbine, and a compressor driven by a high turbine, and burner means for generating hot gases for driving said turbine, engine control means independently controlling the flow of fuel to said burner and controlling the area of said variable exhaust nozzle, said control means including means responsive to a pressure ratio across a station in said engine for generating a first signal, means responsive to engine rotor speed and engine inlet temperature for generating a second signal indicative of a schedule of said pressure ratio, means responsive to said first signal and said second signal for generating a third signal indicative of pressure ratio error, and means responsive to a function of said third signal for generating a fourth signal for biasing said independent engine control means to further adjust said fuel flow to maintain the pressure ratio schedule of said second signal.
The method of controlling a twin spool gas turbine engine of the type that includes a fan driven by the low turbine and has fuel and exhaust nozzle area control during a subsonic and transonic aircraft flight mode comprising the steps of
- scheduling the pressure ratio across an operating station of the engine as a function of corrected fan speed,
- measuring the value of the pressure ratio across that operating station indicated in the previous step,
- calculating an error between the scheduled value of the pressure ratio and the actual value, and
- trimming the amount of fuel flow delivered to the engine in accordance with the error obtained in the step of calculating.
Dependencies are inferred from the claim text.