Gas Turbine Engine Start Control With Inoperable EGT Sensor
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Solution Overview
Problem
Gas turbine engines with inoperable or unavailable exhaust gas temperature sensors cannot be started safely due to the risk of high temperatures, which can reduce the engine's lifespan.
Innovation Solution
A system and method that uses a controller to determine the availability of the exhaust gas temperature sensor, commanding a nominal or off-nominal acceleration rate during start-up, with off-nominal being lower to prevent excessive temperatures if the sensor is unavailable, utilizing light-off logic and acceleration command logic to manage fuel and air combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the APU is prevented from starting up when the EGT sensor is inoperable, then high temperatures and reduced engine life are avoided, but the APU cannot provide power when needed
Solution Approach 1:
The system changes the acceleration rate parameter based on sensor availability. When the EGT sensor is inoperable, the controller commands a reduced acceleration rate during start-up, allowing the APU to operate safely without the sensor while still providing necessary power capability.
Solution Approach 2:
The controller acts as an intermediary between the start-up system and the EGT sensor. It monitors sensor availability and mediates the start-up process by adjusting acceleration commands accordingly, enabling safe operation without direct sensor input.
2Productivity
If the APU starts up with a nominal acceleration rate without EGT sensor input, then power is provided quickly, but excessive temperatures occur that reduce engine life
Solution Approach 1:
The system dynamically changes the acceleration rate parameter based on sensor status. With the EGT sensor inoperable, the controller switches to an off-nominal (reduced) acceleration rate, sacrificing some start-up speed to prevent excessive temperatures and protect engine life.
3Reliability
If the EGT sensor is made inoperable or unavailable, then sensor failure or interference is avoided, but the system cannot monitor exhaust gas temperature
Solution Approach 1:
The controller performs self-diagnosis to detect EGT sensor availability and independently determines whether to proceed with start-up using nominal or reduced acceleration rates, eliminating the need for continuous sensor input while maintaining safe operation.
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
Enables safe start-up of gas turbine engines even when the exhaust gas temperature sensor is inoperable, preventing high temperatures and extending engine life by controlling acceleration rates based on sensor availability.
Implementation Method 1
Fuel is injected into the compressed air within the combustion section to produce the high-energy combusted air to the power turbine section
Implementation Method 2
the compressor section draws in and compresses ambient air and supplies the air to the combustion section
Data Source
AI summary
A system and method are provided for controlling the start-up of a gas turbine engine having an exhaust gas temperature (EGT) sensor. A determination is made as to whether the EGT sensor is available or unavailable. The gas turbine engine is commanded to accelerate at a nominal acceleration rate during the start-up operation if the EGT sensor is available, and to accelerate at an off-nominal acceleration rate during the start-up operation if the EGT sensor is unavailable. The off-nominal acceleration rate is lower than the nominal acceleration rate.