Gas Turbine Compressor Control via Electrical Machines
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Solution Overview
Problem
Gas turbine engines face challenges during start-up or re-light processes due to front end stall in high pressure compressors, which can lead to delayed or aborted processes, and existing solutions like start bleed increase noise and weight, affecting fuel consumption.
Innovation Solution
A method involving electrical machines to control the rotation of low and high pressure compressors, determining flame extinction by torque measurement, and adjusting compressor velocities to prevent stall while maintaining angular velocity thresholds, allowing for controlled ignition and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If start bleed is used to exhaust air from the high pressure compressor to prevent front end stall, then the start-up process reliability is improved, but the noise output increases and weight increases reducing fuel consumption
Solution Approach 1:
The patent removes the start bleed system from the high pressure compressor by implementing independent electrical machine control of the compressors during start-up. This extraction of the bleed system eliminates the source of noise and weight while maintaining start-up reliability through alternative control means.
Solution Approach 2:
The patent replaces the mechanical start bleed system with an electrical control system using independent electrical machines to drive the compressors. This substitution eliminates the need for mechanical bleed paths and their associated noise and weight penalties while achieving the same reliability goal through electrical actuation.
2Reliability
If start bleed is used to exhaust air from the high pressure compressor to prevent front end stall, then the start-up process reliability is improved, but the weight increases reducing brake specific fuel consumption
Solution Approach 1:
The patent removes the start bleed system from the high pressure compressor by implementing independent electrical machine control of the compressors during start-up. This extraction of the bleed system eliminates the source of noise and weight while maintaining start-up reliability through alternative control means.
Solution Approach 2:
The patent replaces the mechanical start bleed system with an electrical control system using independent electrical machines to drive the compressors. This substitution eliminates the need for mechanical bleed paths and their associated noise and weight penalties while achieving the same reliability goal through electrical actuation.
3Stability of the object's composition
If the angular velocity of the high pressure compressor is increased prior to ignition to prevent front end stall, then the compressor stability is improved, but the risk of single cell rotating stall increases which may delay or abort the start-up process
Solution Approach 1:
The patent employs torque measurement feedback from the electrical machines to detect flame extinction conditions and adjust compressor control accordingly. This feedback mechanism allows the system to respond to actual engine conditions, preventing premature acceleration that could cause rotating stall while maintaining stability when appropriate.
Solution Approach 2:
The patent implements dynamic control of compressor angular velocities during start-up using independent electrical machines, allowing the system to adapt acceleration rates based on real-time conditions. This dynamic approach prevents the high pressure compressor from entering unstable operating regions while maintaining stability when conditions are favorable.
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
This approach prevents compressor stall, reduces noise and weight, and improves brake specific fuel consumption by efficiently managing compressor velocities and ignition in gas turbine engines.
Implementation Method 1
controlling rotation a low pressure compressor using a first electrical machine (54), and controlling rotation a high pressure compressor using a second electrical machine (56)
Implementation Method 2
Determining when the flame is extinguished comprises measuring a change in one or more of: a torque applied by the first electrical machine (54); and a torque applied by the second electrical machine (56)
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A method (400) of controlling at least part of a start-up or re-light process of a gas turbine engine (10), the method (400) comprising: determining (402) when a flame in a combustion chamber (16) of a gas turbine engine (10) is extinguished, during a start-up process or re-light process or during operation; purging (404) the combustion chamber (16) by controlling rotation of a low pressure compressor (14) using a first electrical machine (54), and controlling rotation of a high pressure compressor (15) using a second electrical machine (56), the combustion chamber (16) downstream of the low pressure compressor (14) and high pressure compressor (15); and controlling (406) rotation of the low pressure compressor (14) using the first electrical machine (54), and controlling rotation of the high pressure compressor (15) using the second electrical machine (56) to restart the start-up process or perform the re-light process.