Gas Turbine Combustor Pulsation Protection via Frequency Band Weighting
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Solution Overview
Problem
Current gas turbine engine protection methods rely on empirical evidence and fail to accurately link acoustic pulsations with structural lifetime, leading to suboptimal engine adjustments and potential early shutdowns, as they do not account for structural resonances and do not provide a comprehensive approach to managing combustor pulsations for maximum power and efficiency.
Innovation Solution
A method involving the measurement of combustor pulsations, division into frequency bands, computation of root mean square values, weighting with structural models to predict lifetime, and comparison to a Pulsation Limit Criterion (PLC) value to adjust engine operation within safe limits, ensuring optimal lifetime and power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If empirical evidence and damage profiles are used to define protection thresholds, then engine protection actions can be initiated, but the confidence in protection accuracy is limited and suboptimal engine adjustments occur
Solution Approach 1:
The patent replaces empirical mechanical damage assessment with a physics-based acoustic-structural coupling model. It uses structural models to compute stresses from acoustic loads, transforming the protection approach from experience-based to science-based, thereby improving accuracy and establishing a direct link between pulsations and structural lifetime.
Solution Approach 2:
The patent introduces structural models as intermediaries between acoustic pulsation measurements and structural lifetime assessment. These models compute stresses and fatigue damage by coupling acoustic loads with structural responses, providing the missing link between acoustic data and structural integrity that empirical methods cannot establish.
2Productivity
If the highest peak of the dominant acoustic mode is reduced by adjusting combustion parameters, then power and efficiency are optimized, but structural resonances at lower frequencies may still be excited causing premature shutdowns
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands and identifies all significant acoustic modes, not just the dominant peak. It analyzes the complete spectral content to detect resonances at various frequencies, allowing comprehensive protection against structural excitation while maintaining optimal combustion settings for power and efficiency.
Solution Approach 2:
The patent dynamically adjusts combustion parameters based on real-time pulsation characteristics and identified resonances. It continuously monitors acoustic modes and adapts operating conditions to avoid exciting structural resonances, enabling the engine to operate at optimal power levels without premature shutdowns due to undetected resonant conditions.
3Device complexity
If analogue filters are used for signal processing, then filtering is performed, but crosstalk between neighbouring frequency bands occurs reducing measurement precision
Solution Approach 1:
The patent replaces analogue filters with digital signal processing techniques. It uses Fast Fourier Transform (FFT) and digital filtering algorithms to achieve precise frequency band separation without the crosstalk problems of analogue filters, maintaining simple implementation while significantly improving measurement precision.
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 allows for precise adjustment of engine parameters to maximize power and efficiency while ensuring the structural integrity of gas turbine components, providing a direct link between acoustic pulsations and structural lifetime, reducing unnecessary shutdowns and extending maintenance cycles.
Implementation Method 1
The conversion of the physical hot gas pressure fluctuation into an electric output signal (high frequency, voltage or current or digital) is performed by a high temperature dynamic sensor (microphone, dynamic pressure transducer, dynamic pressure pick-up; piezo-electric, piezo-resistive, capacitor, strain gage, optical or any other principle)
Implementation Method 2
The conversion of the physical hot gas pressure fluctuation into an electric output signal (high frequency, voltage or current or digital) is performed by a high temperature dynamic sensor (microphone, dynamic pressure transducer, dynamic pressure pick-up; piezo-electric, piezo-resistive, capacitor, strain gage, optical or any other principle)
Implementation Method 3
The conversion of the physical hot gas pressure fluctuation into an electric output signal (high frequency, voltage or current or digital) is performed by a high temperature dynamic sensor (microphone, dynamic pressure transducer, dynamic pressure pick-up; piezo-electric, piezo-resistive, capacitor, strain gage, optical or any other principle)
Implementation Method 4
These waves excite the thermally highly loaded structures of the combustor. If the mechanical vibrations of combustor hot gas parts match in some ways with the acoustic pulsation load, significant wear leading to a lifetime reduction or even immediate failure occurs.
Implementation Method 5
If the mechanical vibrations of combustor hot gas parts match in some ways with the acoustic pulsation load, significant wear leading to a lifetime reduction or even immediate failure occurs.
Data Source
Figure 1
AI summary
The invention relates to a method for protecting a gas turbine engine (10), comprising a compressor (11), a combustor (13) and a turbine (12), against high dynamical process values, especially in combustor/flame pulsations. An effective protection against high dynamical process values, especially in combustor/flame pulsations is achieved by providing the steps of o) measuring the pulsations of the combustor (13) with a suitable sensor (18), p) dividing the frequency spectrum of the measured pulsation signal up into pre-defined band pass sections, q) computing the rms (root mean square) of the signal for each band, r) weighting the computed frequency/frequency band rms with predetermined weighting factors, s) cumulating the weighted frequency/frequency band rms values to get a Pulsation Limit Criterion (PLC) value, t) comparing the PLC value with at least one reference value (23), and u) operating the gas turbine engine (10) according to the result of said comparison.