Gas Turbine Engine Startup Control for High-Altitude Ignition
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Solution Overview
Problem
Starting a gas turbine engine at high altitudes is challenging due to low air density and high velocity, which affects engine startup reliability and speed.
Innovation Solution
A system and method utilizing an electric machine to drive the rotating assembly of the gas turbine engine, coupled with a controller to manage fuel injection and ignition, and a surge control system to optimize startup parameters such as air density and temperature, ensuring a stable air-fuel ratio and preventing compressor surge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional starting systems are used at high altitude, then the engine can attempt to start, but the startup reliability deteriorates due to low air density and high velocity
Solution Approach 1:
The system dynamically adjusts starting parameters including fuel flow rate, air valve timing, and compressor blade positioning based on detected altitude and environmental conditions. This optimization of parameters ensures reliable ignition and stable combustion despite high altitude challenges of low air density and high velocity
Solution Approach 2:
The control system continuously monitors engine parameters such as rotational speed, temperature, and pressure during the starting sequence. Based on this feedback, the system automatically adjusts fuel injection, air intake, and ignition timing to maintain optimal combustion conditions and ensure successful startup at high altitude
2Productivity
If conventional starting systems are used at high altitude, then the engine can attempt to start, but the startup speed deteriorates
Solution Approach 1:
The system performs preliminary actions before the main starting sequence by pre-positioning the compressor blades, pre-opening air valves, and pre-priming the fuel system. This preparation ensures that when the engine starts, all systems are ready to immediately establish stable combustion, significantly reducing startup time at high altitude
Solution Approach 2:
The control system dynamically adjusts multiple parameters during the starting sequence including progressively opening air valves, modulating fuel flow rate, and adjusting ignition timing based on real-time engine response. This dynamic optimization accelerates the startup process while maintaining stability despite high altitude conditions
3Reliability
If fuel is directed into the combustion chamber, then combustion can occur, but the air-fuel ratio becomes difficult to control independent of rotating assembly speed
Solution Approach 1:
The system replaces mechanical fuel metering mechanisms with electronically controlled fuel injection. This allows the fuel flow rate to be precisely controlled by the control system based on detected engine parameters and desired air-fuel ratio, rather than being passively determined by rotating assembly speed. The electronic control enables accurate maintenance of stoichiometric or lean burn conditions regardless of engine speed variations
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
Improves engine startup reliability and speed at high altitudes by providing a controlled air-fuel ratio and preventing compressor surge, thereby enhancing overall engine performance.
Implementation Method 1
an electric machine to drive rotation of the rotating assembly of the gas turbine engine
Implementation Method 2
the one or more ignitors may be used to ignite the mixture of the fuel and the compressed air within the combustion chamber
Data Source
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AI summary
An operating method is provided during which a plurality of start parameters for a gas turbine engine are determined (402). A first of the start parameters is indicative of a temperature of air at an inlet into the gas turbine engine. A second of the start parameters is indicative of a pressure of the air at the inlet. Rotation of a rotating assembly of the gas turbine engine (22) is driven (404). The rotating assembly includes a compressor rotor and a turbine rotor. Fuel is directed (408) into a combustion chamber of the gas turbine engine based on the start parameters and a speed parameter. The speed parameter is indicative of a speed of the rotation of the rotating assembly. A mixture of the fuel and compressed air within the combustion chamber is ignited (410) to start the gas turbine engine.