Gas-Turbine Fuel Command Control for Thrust Stability
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Solution Overview
Problem
Existing control systems for gas-turbine aeroengines fail to effectively suppress engine thrust fluctuations caused by air quantity changes due to the opening and closing of the Bleed Off Valve (BOV), leading to unnatural engine behavior.
Innovation Solution
A control apparatus that calculates a desired low-pressure turbine rotational speed based on the thrust lever operation angle and adjusts the fuel command in conjunction with determining the optimal time to open or close the BOV, ensuring the fuel command is supplied accordingly to mitigate thrust fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fuel supply command value is calculated as a ratio of fuel quantity to compressor outlet pressure, then fuel supply control is achieved, but engine thrust fluctuation occurs due to air quantity changes from BOV opening/closing
Solution Approach 1:
The control apparatus determines the time point for BOV open/close commands in advance and supplies the fuel command based on this predetermined time point, rather than reacting to pressure changes after they occur. This preliminary timing coordination prevents thrust fluctuations by synchronizing fuel supply adjustments with anticipated air quantity changes from BOV operations.
Solution Approach 2:
The system continuously monitors BOV command timing and uses this information to adjust fuel supply commands in real-time. By feedback from the BOV control timing, the fuel command is dynamically adjusted to compensate for air quantity fluctuations, maintaining stable engine thrust despite changes in compressor outlet pressure.
2Stress or pressure
If the BOV is closed to reduce bleed air, then compressor outlet pressure rises, but this causes unnatural engine thrust increase due to fuel quantity increase
Solution Approach 1:
When a BOV close command is determined, the system preemptively adjusts the fuel command in the opposite direction (reducing fuel supply) to counteract the expected pressure rise and resulting thrust increase. This preliminary anti-action compensates for the air quantity change before it fully manifests, preventing unnatural thrust variations.
3Stability of the object's composition
If the fuel supply valve opening is regulated to suppress engine thrust fluctuation, then thrust stability improves, but air quantity fluctuation from BOV operations is not addressed
Solution Approach 1:
The control apparatus introduces an intermediary timing determination mechanism that mediates between BOV commands and fuel supply adjustments. By determining the optimal time point for BOV commands and using this as the basis for fuel command timing, the system coordinates both control actions to work together, ensuring both thrust stability and proper response to air quantity fluctuations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively compensates for response delays and reduces engine thrust fluctuations related to air quantity changes, providing a smoother and more stable engine operation by anticipating and adjusting fuel supply in synchronization with BOV operations.
Implementation Method 1
a high-pressure compressor connected to the high-pressure turbine and adapted to compress air to be introduced into the combustion chamber
Implementation Method 2
ignition and combustion of an air-fuel mixture in a combustion chamber
Implementation Method 3
a high-pressure turbine rotated by injection of high-pressure gas produced upon ignition/combustion of an air-fuel mixture
Implementation Method 4
a low-pressure turbine located downstream of the high-pressure turbine to be rotated by low-pressure gas exiting the high-pressure turbine
Implementation Method 5
a bleed-off valve equipped at a high-pressure compressor connected to the high-pressure turbine and adapted to be open to bleed off air flowing through a compression passage
Data Source
AI summary
An apparatus for controlling a gas-turbine aeroengine is configured to calculate a fuel command to supply fuel based on a calculated desired rotational speed of a low-pressure turbine calculated from an operation angle of a thrust lever installed at an aircraft cockpit pilot's seat, determines whether it is a time point for outputting a command to open/close a bleed-off valve equipped at a high-pressure compressor connected to a high-pressure turbine and to supply the fuel command based on the time point when it is determined to be the time point for outputting the command to open/close the bleed-off valve.