Method and system for detecting flame holding in a turbine assembly

Abstract

A method for detecting flame holding in at least one combustor of a turbine engine includes measuring dynamic pressure data of at least one combustor of the turbine engine, converting the dynamic pressure data into a frequency domain spectral energy amplitude of the dynamic pressure data, and comparing the spectral energy amplitude to a dynamic amplitude threshold to determine whether the amplitude exceeds a threshold minimum amplitude value, wherein exceeding the dynamic amplitude threshold indicates the occurrence of flame holding.

Description

[Technical Field]

[0001] The present disclosure relates generally to turbine engine assemblies, and more particularly to methods and systems for detecting flame holding in turbine engine assemblies during turbine operation. [Background technology]

[0002] At least some known turbine engines are used to generate electricity in combined heat and power plants and power plants. Such engines can have high specific work and power requirements per unit mass flow. One requirement of power-generating gas turbines relates to the emissions they produce, typically nitrous oxides and carbon dioxide. These emissions can result from incomplete combustion of hydrocarbon fuels, such as natural gas. Premixing fuel and air prior to combustion, such as in a fuel nozzle or fuel injector, can contribute to more complete combustion and lower emissions.

[0003] To further reduce greenhouse gas emissions, at least some known turbine engines, such as gas turbine engines, include fuel nozzles that operate with increased concentrations of hydrogen gas in the fuel mixture. Normal operation of these fuel nozzles requires preventing flame formation within the fuel nozzle itself. Hydrogen is a more volatile fuel than natural gas and generates flames at greater velocities than flames generated using natural gas alone. As a result, hydrogen flames can accidentally form within the fuel nozzle due to momentary upset conditions, such as sudden gas turbine transients or momentary changes in fuel supply conditions.

[0004] Typically, fuel nozzles are not designed to withstand the high temperatures of ignited combustion gases generated in the combustion chamber. Under certain unintended conditions, operation of a combustor using fuels containing high concentrations of hydrogen can cause flames to “flash back” from the combustion zone into the fuel nozzle, where the flame can continue to burn—a condition known as “flame holding.” Another issue that can lead to flame holding is an increased concentration of hydrogen in the fuel mixture compared to traditional fuel sources that are solely or primarily natural gas (e.g., methane). High concentrations of hydrogen in the fuel supply promote higher flame speeds than natural gas, making flashbacks more likely and creating an environment in which flame holding is more difficult to extinguish. Flashback and flame holding can each damage the fuel nozzle and form hot streaks that exceed the local maximum operating temperatures of turbine components, potentially causing mechanical turbine failure or stall. Furthermore, exceeding the flame holding margin can also limit the useful life of the fuel nozzle and / or cause damage to the surrounding combustor liner.

[0005] Therefore, to enable gas turbine operation at higher hydrogen concentrations, there is a need to compensate for the increased risk of flame holding. More specifically, there is a need to accurately detect and monitor flame holding events and conditions during operation and mitigate such conditions in real time to facilitate reducing the likelihood of the gas turbine stalling, failure, or hardware damage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2010-0280732 Summary of the Invention

[0007] In one embodiment, a method for detecting flame holding in a turbine engine is provided, the method including measuring dynamic pressure in at least one combustor of the turbine engine, converting the dynamic pressure data to a frequency domain spectral energy amplitude associated with the dynamic pressure data, and comparing the frequency domain spectral energy amplitude to a dynamic amplitude threshold to determine whether the spectral energy amplitude exceeds the dynamic amplitude threshold, wherein a spectral energy amplitude exceeding the dynamic amplitude threshold indicates the occurrence of flame holding.

[0008] In another exemplary embodiment, a method for operating a turbine engine with an increased hydrogen concentration is provided. The method includes supplying a fuel mixture having a second hydrogen gas concentration to at least one combustor of the turbine engine. The second hydrogen gas concentration defines an extended flame-holding margin window for the turbine engine, the extended flame-holding margin window resulting in reduced emissions and reduced audible noise for the turbine engine. The method further includes measuring dynamic pressure data within at least one combustor of the turbine engine, converting the dynamic pressure data to a frequency-domain spectral energy amplitude associated with the dynamic pressure data, and comparing the spectral energy amplitude to a dynamic amplitude threshold to determine whether the spectral energy amplitude exceeds the dynamic amplitude threshold. A spectral energy amplitude exceeding the dynamic amplitude threshold indicates a flame-holding event. The method further includes mitigating a flame-holding condition in the at least one combustor by adjusting a hydrogen gas concentration of the fuel mixture supplied to the at least one combustor from the second hydrogen gas concentration to a first hydrogen gas concentration. The second hydrogen gas concentration is greater than the first hydrogen gas concentration, and the first hydrogen gas concentration defines a normal operating window.

[0009] In another exemplary embodiment, a system for facilitating operation of at least one combustor of a turbine engine within a flame-holding margin is provided. The system includes a fuel injection system coupled in flow communication with a mixed fuel supply for supplying a fuel mixture to at least one fuel injector in the at least one combustor of the turbine engine. The fuel mixture has a hydrogen gas concentration adjustable from a first hydrogen gas concentration to a second hydrogen gas concentration, the second hydrogen gas concentration being higher than the first hydrogen gas concentration. The system further includes a detection system including a processor and a plurality of dynamic pressure sensors. The processor is programmed to supply the fuel mixture having the second hydrogen gas concentration to the turbine engine. The second hydrogen gas concentration defines an extended flame-holding margin window for the turbine engine, and the extended flame-holding margin window enables the turbine engine to operate with higher mechanical power output, reduced emissions, and reduced audible noise compared to a turbine engine operating with the first hydrogen gas concentration. The processor is further programmed to receive dynamic pressure data measured within at least one combustor of the turbine engine from one or more of the plurality of dynamic pressure sensors and convert the dynamic pressure data into a frequency domain spectral energy amplitude associated with the dynamic pressure data. The processor is further programmed to compare the spectral energy amplitude to a dynamic amplitude threshold to determine whether the spectral energy amplitude exceeds the dynamic amplitude threshold. A spectral energy amplitude exceeding the dynamic amplitude threshold indicates flame holding. The processor is further programmed to reduce a hydrogen gas concentration of the fuel mixture from a second hydrogen gas concentration to a first hydrogen gas concentration. The first hydrogen gas concentration corresponds to a standard operating window in which the likelihood of flame holding is reduced compared to the expanded flame holding margin window. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view of an exemplary turbine engine. [Figure 2] 2 is a schematic diagram of an exemplary detection system that may be used to detect flame holding in a combustor of a turbine engine, such as the turbine engine shown in FIG. 1; [Figure 3] 1 shows an exemplary graph of dynamic pressure measurements over time. [Figure 4A] 1 shows an exemplary graph of dynamic pressure magnitude over a range of frequencies during nominal operation. [Figure 4B] 1 shows an exemplary graph of dynamic pressure magnitude over a range of frequencies during a flameholding event. [Figure 5A] 10 shows an expanded view of an exemplary graph of dynamic pressure magnitude over a range of frequencies during nominal operation. [Figure 5B] 10 shows a close-up view of an exemplary graph of dynamic pressure magnitude over a range of frequencies during a flame-holding event. [Figure 6] 1 shows an exemplary graph of dynamic amplitude over time. [Figure 7] 1 illustrates a flowchart of an exemplary method for detecting and mitigating flame holding in a combustor of a turbine engine. [Figure 8] 1 illustrates a flowchart of an exemplary method for operating a turbine engine at increased power output while mitigating flame holding risk. DETAILED DESCRIPTION OF THE INVENTION

[0011] The exemplary methods, apparatus, and systems described herein overcome at least some known drawbacks associated with at least some known combustion systems for turbine engines by monitoring and detecting flame holding or flame holding conditions in real time during normal operation of the turbine engine. By monitoring flame holding or flame holding conditions in real time, the turbine engine may operate with fuels having higher hydrogen concentrations.

[0012] As used herein, the terms "flame holding," "flame holding event," and "flame holding occurrence" are intended to mean a condition in which operation of a combustor using fuels with high concentrations of hydrogen can cause a flame to "flash back" from the combustion zone to the fuel nozzle, where the flame can continue to burn. For purposes of this disclosure, flame holding occurs within the combustion zone or in the combustor.

[0013] Embodiments described herein provide a flame holding detection system for use with a gas turbine engine, and a method for detecting flame holding during operation of the turbine engine. The systems and methods described herein may also be configured to mitigate a flame holding condition (for example, by reducing the concentration of hydrogen gas in a fuel mixture injected into the gas turbine engine). It should also be understood that the term "fluid" as used herein includes any medium or material that flows, including, but not limited to, gaseous fuels and air.

[0014] 1 is a schematic cross-sectional view of an exemplary turbine engine 10. More specifically, turbine engine 100 is a gas turbine engine. While the exemplary embodiments are shown in connection with a gas turbine engine, the present disclosure is not limited to any one particular engine, and those skilled in the art will understand that the systems and methods may be used in connection with other turbine engines. As used herein, the terms "turbine," "turbine assembly," and "turbine engine" shall be used interchangeably.

[0015] In the exemplary embodiment, turbine engine 100 includes an intake section 112, a compressor section 114 coupled downstream from intake section 112, a combustor section 116 coupled downstream from compressor section 114, a turbine section 118 coupled downstream from combustor section 116, and an exhaust section 120. Turbine section 118 is coupled to compressor section 114 via a rotor shaft 122. In the exemplary embodiment, combustor section 116 includes a plurality of combustors 124 (e.g., “n” combustor cans arranged in an annular array around rotor shaft 122), where n is typically, but is not limited to, 8, 10, 12, or 16 combustors 124. Combustor section 116 is coupled to compressor section 114 such that each combustor 124 is positioned in flow communication with compressor section 114. A fuel injector 126 is coupled to each combustor 124. Turbine section 118 is coupled to compressor section 114 and to a load 128, such as, but not limited to, an electrical generator and / or a mechanical drive application. In the exemplary embodiment, each compressor section 114 and turbine section 118 includes at least one rotor disk assembly that is coupled to a rotor shaft 122 to form a rotor assembly.

[0016] During operation, intake section 112 channels air toward compressor section 114, where the air is compressed to a higher pressure and temperature before being discharged toward combustor section 116. Within each combustor 124, the compressed air is mixed with a fuel or fuel mixture and ignited to generate combustion gases that are channeled toward turbine section 118. More specifically, in combustor 124, a fuel mixture (e.g., natural gas and hydrogen) is injected into the airflow, and the fuel-air mixture is ignited to generate hot combustion gases that are channeled toward turbine section 118. Turbine section 118 converts thermal energy from the gas stream into mechanical rotational energy as the combustion gases impart rotational energy to turbine section 118 and rotor assembly 132. The mechanical rotational energy drives rotor shaft 122 and a generator 128 coupled to rotor shaft 122 to generate electricity.

[0017] The fuel injectors 126 are coupled in fluid communication with the mixed fuel supply 150 as part of a fuel injection system 154. The fuel injection system 154 includes a hydrogen fuel supply 160 and a natural gas (e.g., methane) fuel supply 170, a mixing valve 172 (e.g., a three-way valve) in fluid communication with the hydrogen fuel supply 160 and the natural gas supply 170, the mixed fuel supply 150 receiving the mixture of fuels from the mixing valve 172, and a plurality of fuel distribution valves 152 (only one of which is shown for clarity) for directing the fuel mixture to the fuel injectors 126 of each combustor 124. The mixing valve 172 is in communication with a controller 200 to adjust the ratio of hydrogen to natural gas, thereby producing a mixed fuel in the mixed fuel supply 150 having a desired hydrogen gas concentration.

[0018] Fuel from the hydrogen fuel source 160 and the natural gas fuel source 170 is metered through a mixing valve 172 coupled to a controller 200 to allow a desired hydrogen concentration of the fuel mixture to be provided to the mixed fuel source 150. The hydrogen gas concentration in the mixed fuel source 150 ranges from a first hydrogen gas concentration to a second hydrogen gas concentration, where the first hydrogen gas concentration is greater than zero (i.e., some hydrogen gas is mixed with the natural gas) and the second hydrogen gas concentration is greater than the first hydrogen gas concentration. In some embodiments, the fuel injection system 154, in response to the controller 200, can selectively adjust the hydrogen concentration of the fuel mixture to any desired hydrogen concentration between the first hydrogen gas concentration and the second hydrogen gas concentration, including the first hydrogen gas concentration and the second hydrogen gas concentration. Operating the turbine engine 100 at the second hydrogen gas concentration leads to lower greenhouse gas emissions from the turbine engine 100 compared to operating the turbine engine 100 at the first hydrogen gas concentration. However, at the second hydrogen gas concentration, the turbine engine 100 is generally more susceptible to flame holding due to the presence of the higher hydrogen gas concentration because hydrogen is highly reactive and diffusive, producing a fast, short flame.

[0019] As used herein, the term “standard operating window” of turbine engine 100 refers to an operating condition of turbine engine 100 in which combustor 124 is operating with a fuel mixture having a first hydrogen gas concentration, and the term “extended flameholding margin” or “extended flameholding margin window” of turbine engine 100 refers to an operating condition of turbine engine 100 in which combustor 124 is operating with a fuel mixture having a second hydrogen gas concentration. Mixing valve 172 is adjusted via a signal from controller 200 to supply a fuel mixture having a desired hydrogen gas concentration to mixed fuel source 150. Turbine engine 100 operating within the extended flameholding margin window has greater mechanical power output compared to turbine engine 100 operating within the standard operating window, but the extended flameholding margin window increases the likelihood of flameholding occurring in combustor 124.

[0020] Similar to the hydrogen gas concentration, in some embodiments, the mixed fuel supply 150 can be metered to selectively adjust the fuel supply pressure, or more generally, the fuel injector pressure ratio, where the fuel injector pressure ratio is defined as the fuel supply pressure divided by the combustor pressure. An increased fuel injector pressure ratio produces a more intense combustion. It should be understood that the above-mentioned parameters of the turbine engine 100 (such as, but not limited to, the hydrogen concentration in the fuel mixture, the fuel injector pressure ratio, the velocity of the fuel mixture, and / or the temperature of the fuel mixture) are set to normally operate in a standard operating window where the likelihood of flame holding is reduced compared to the expanded operating window. The temperature of the fuel mixture is regulated by a heat exchanger in communication with the controller 200 (of FIGS. 1 and 2). The heat exchanger can be positioned downstream of the mixed fuel supply 150. The temperature of the fuel mixture is regulated by increasing or decreasing the operation of the heat exchanger.

[0021] To reduce emissions from the turbine engine 100, one or more of the above parameters are increased or adjusted to operate the turbine engine 100 within an increased flame-holding margin window. It should be understood that the flame-holding margin is fuel-specific and turbine-engine-specific.

[0022] 2 and the exemplary methods illustrated in FIGS. 7 and 8 can be used to monitor and detect flame holding within turbine engine 100, thereby enabling turbine engine 100 to operate more efficiently near or within the flame holding margin. Detection system 250 includes controller 200 and sensor 208. In some embodiments, detection system 250 can mitigate flame holding within turbine engine 100 by selectively reducing the supply of hydrogen gas concentration in the fuel mixture, for example, by reducing the supply of hydrogen gas concentration from a second hydrogen gas concentration to a first hydrogen gas concentration or to a desired hydrogen gas concentration between the first and second hydrogen gas concentrations. One skilled in the art will appreciate that any of the above parameters can also, or alternatively, be adjusted to change turbine engine 100 from operating within an extended flame holding margin window to operating within a standard operating window, thus mitigating the possibility of flame holding when detection system 250 detects flame holding in one of combustors 124.

[0023] 2 illustrates an exemplary detection system 250 including a controller 200 communicatively coupled to components of turbine engine 100. Controller 200 includes a processor 202, a local memory 204, and a communication interface 206, and detection system 250 further includes a plurality of sensors 208 in communication with controller 200. Specifically, the plurality of sensors 208 are communicatively coupled to processor 202 (as indicated by double-dashed lines). In some embodiments, communication interface 206 and controller 200 are coupled to at least fuel injector 126, intake section 112, and mixing fuel valve(s) 152, as shown in FIG. 1 . In some embodiments, communication interface 206 includes a programmable logic controller that controls at least fuel injector 126, intake section 112, mixing valve 172, and mixing fuel valve(s) 152. In some embodiments, the communication interface 206 is configured to selectively increase or decrease the hydrogen gas concentration of the fuel mixture from a first hydrogen gas concentration to a second hydrogen gas concentration, or to any desired value therebetween, by adjusting the mixing valve 172 to introduce different amounts of hydrogen gas.

[0024] To mitigate flame holding, it may be desirable in some cases to redistribute the fuel mixture within the combustor 124 (e.g., among the various fuel injectors 126). Accordingly, as shown in FIG. 2, each combustor 124 may include multiple fuel mixing valves 152. Each of the fuel mixing valves 152 of each combustor 124 may be in communication with a controller 200 for optimal control of the fuel mixture delivered to the fuel injectors 126 of each combustor 124. While FIG. 2 illustrates each combustor 124 of the “n” combustor cans as having three fuel distribution valves 152, it should be understood that each combustor 124 may have fewer or more distribution valves 152.

[0025] The sensors 208 are positioned at various locations within the turbine engine 100 (denoted by the letter "S" in FIG. 1 ). The sensors 208 are configured to measure at least dynamic pressure and temperature in an area local to where the sensors 208 are positioned. In some embodiments, the sensors 208 are dynamic pressure sensors. In some embodiments, the sensors 208 are temperature sensors. In some embodiments, the sensors 208 are thermocouples. In some embodiments, the temperature sensors and / or dynamic pressure sensors 208 are positioned in one or more of the intake section 112, the compressor section 114, the combustor section 116, and the turbine section 118. In some embodiments, the temperature sensors and / or dynamic pressure sensors 208 are positioned in a combustor liner or combustor head end (e.g., proximate the fuel injectors 126).

[0026] The processor 202 is configured to execute instructions. For example, executable instructions are stored in memory 204, and the processor 202 may include one or more processing units (e.g., in a multi-core configuration). The one or more processing units suitably perform the respective functions of the processor 202 and execute all or a portion of the instructions. As used herein, the term processor refers to a central processing unit, a microprocessor, a microcontroller, a reduced instruction set circuit (RISC), an application specific integrated circuit (ASIC), a programmable logic circuit (PLC), and any other circuit or processor capable of performing the functions described herein. The foregoing are examples only and are thus not intended to limit in any way the definition and / or meaning of the term "processor."

[0027] Local memory 204 stores non-transitory computer-readable instructions for execution of the techniques described herein. Such instructions, when executed by processor 202, cause processor 202 to perform at least a portion of the methods described herein. In some embodiments, memory 204 stores computer-readable instructions for providing a user interface to a user via a media output component and receiving and processing input from an input device. Memory 204 may include, but is not limited to, random access memory (RAM), such as dynamic RAM (DRAM) or static RAM (SRAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and non-volatile RAM (NVRAM). Although shown as separate from processor 202, in some embodiments, memory 204 is combined with processor 202, such as in a microcontroller or microprocessor, but may still be referred to separately. The above memory types are merely examples and, thus, are not limiting with respect to the types of memory usable for storing computer programs.

[0028] In some embodiments, the controller 200 includes or is connected to a communications interface 206, which is an input device for receiving input from a user. An input device is any device that enables the controller to receive analog and / or digital commands, instructions, or other input from a user, including visual, audio, touch, button presses, stylus taps, etc. An input device may include, for example, a variable resistor, an input dial, a keyboard / keypad, a pointing device, a mouse, a stylus, a touch-sensitive panel (e.g., a touchpad or touchscreen), a gyroscope, an accelerometer, a position detector, an audio input device, or any combination thereof. A single component, such as a touchscreen, can function as both an output device and an input device for a media output component.

[0029] The communication interface 206 allows the controller 200 to communicate with remote devices and systems forming the network 210, such as remote sensors, remote databases, and remote controllers, and may include one or more communication interfaces for interacting with one or more remote devices or systems. The communication interface 206 may be a wired or wireless communication interface that allows the controller 200 to communicate with remote devices and systems directly or via the network 210. The wireless communication interface may include a radio frequency (RF) transceiver, a Bluetooth adapter, a Wi-Fi transceiver, a ZigBee transceiver, a near field communication (NFC) transceiver, an infrared (IR) transceiver, and / or any other device and communication protocol for wireless communication. (Bluetooth is a registered trademark of the Bluetooth Special Interest Group, Kirkland, Washington, and ZigBee is a registered trademark of the ZigBee Alliance, San Ramon, California.) The wired communication interface may use any suitable wired communication protocol for direct communication, including, but not limited to, USB, RS232, I2C, SPI, analog, and proprietary IO protocols. In some embodiments, the wired communication interface includes a wired network adapter that allows the controller 200 to be coupled to a network such as the Internet, a local area network (LAN), a wide area network (WAN), a mesh network, and / or any other network for communicating with remote devices and systems via network 210.

[0030] 3 shows an example graph of dynamic pressure DP measurements collected over time from at least one dynamic pressure sensor 208 in combustor section 116. In some embodiments, dynamic pressure is measured in pounds per square inch (PSI) and time is measured in seconds. Dynamic pressure sensor 208 continuously measures dynamic pressure data DP and transmits the dynamic pressure data to controller 200, and more specifically, processor 202. Dynamic pressure data DP is measured in the time domain by dynamic pressure sensor 208. In some embodiments, processor 202 stores dynamic pressure data DP from at least one dynamic pressure sensor 208 in memory 204. Processor 202 is configured to process the dynamic pressure data in the time domain by mathematical integration (algorithm) to obtain output data in the frequency domain.

[0031] In some embodiments, the algorithm is a mathematical integral, such as a Fourier transform. In some embodiments, the algorithm is a fast Fourier transform (FFT). In some embodiments, the algorithm is a discrete Fourier transform. In some embodiments, the processor 202 utilizes conventional multi-paradigm programming languages ​​and numerical computation in general. The algorithm converts time domain data into frequency domain amplitude. While a time domain graph shows the change in a signal or data over time, a frequency domain graph shows the amplitude of the data or signal within a given frequency band over a range of frequencies.

[0032] 4A and 4B show example graphs of output data in the form of dynamic amplitude DA over an example frequency range. FIG. 4A shows dynamic amplitude DA over an example frequency range during normal operation of the combustor 124, excluding the occurrence of a flame-holding event. In contrast, FIG. 4B shows dynamic amplitude DA over the same frequency range as shown in FIG. 4A, with a flame-holding event occurring in characteristic frequency sub-range F1. FIG. 5A shows an expanded view of FIG. 4A at characteristic frequency sub-range F1 (as shown in FIG. 4A), and FIG. 5B shows an expanded view of FIG. 4B for the same frequency sub-range F1 (as shown in FIG. 4B). The dynamic amplitude DA shown in FIGS. 4A, 4B, 5A, and 5B is specific to an example turbine engine and is not intended to be limiting, and it should be understood that other dynamic amplitudes may be applicable to other turbine engines.

[0033] As shown in Figures 4A and 4B, the dynamic amplitude DA exhibited by the combustor 124 under normal operating conditions (as in Figure 4A, where no flame holding event is occurring) and the dynamic amplitude DA exhibited by the combustor 124 experiencing a flame holding event (Figure 4B) are substantially the same, except for the dynamic amplitude DA within the characteristic frequency subrange F1. As shown in Figures 5A and 5B, the occurrence of flame holding is reflected by an increase in the dynamic amplitude DA, with the peak dynamic amplitude DA1 resulting from the flame holding occurrence being measurably greater than the peak dynamic amplitude DA2 under normal operating conditions (i.e., non-flame holding). Figures 5A and 5B are displayed on the same scale as each other for comparison. In the exemplary graphs of Figures 4A, 4B, 5A, and 5B, the peak dynamic amplitude DA1 during a flame holding occurrence is approximately twice the peak dynamic amplitude DA2 during a non-flame holding occurrence. It should be understood that other ratios of peak dynamic amplitude during flame holding to peak dynamic amplitude during non-flame holding may vary for other exemplary turbine engines, and such peak dynamic amplitudes may occur in different characteristic frequency sub-ranges.

[0034] The substantially larger peak dynamic amplitude (DA1) during flame holding is detectable in laboratory measurements and is larger than the peak dynamic amplitude produced by noise or other factors. In an exemplary turbine engine, experimental testing of the turbine engine 100 in a controlled environment can be implemented to determine the ratio of the peak dynamic amplitude (DA1) during flame holding to the peak dynamic amplitude (DA2) during non-flame holding. Thus, through experimental testing and observation of the dynamic amplitude for the characteristic frequency subrange F1, a dynamic amplitude threshold TL (as shown in FIG. 6) is determined, and a correlation between dynamic amplitude above the threshold and flame holding is demonstrated.

[0035] 6 shows an exemplary graph of output data in the form of dynamic amplitude DA taken over a period of time. Amplitude A1 (shown as a solid line) represents the peak-hold, and amplitude A2 (shown as a dashed line) represents the spectral energy integral. As used herein, the spectral energy integral is the integral function of the amplitude over the frequency subrange F1. Furthermore, as used herein, the "peak-hold" graph A1 is a quadratic trace graph showing the highest amplitude value for each frequency of the spectral energy integral of amplitude A2.

[0036] As can be seen by comparing Figures 3 and 6, dynamic pressure fluctuations due to flame holding are difficult to detect in the time domain. This is due to the lack of resolution and accompanying noise present in the system. Analyzing the amplitudes A1 and A2 in the frequency domain produces a frequency amplitude or peak corresponding to flame holding. As shown in Figure 6, flame holding is represented by a period P1 (measured in seconds) during which the amplitudes of both the spectral energy amplitude A2 and the peak-hold amplitude A1 exceed the dynamic amplitude threshold TL. In contrast, during period P2, the peak-hold amplitude A1 exceeds the dynamic amplitude threshold TL, but no flame holding event has occurred. Measuring and detecting amplitude using only the peak-hold method would give a false indication of flame holding. The amplitude from the spectral energy integration method (spectral energy amplitude A2) shows an amplitude level below the dynamic amplitude threshold TL, thus accurately indicating that there was no flame holding event.

[0037] To determine whether a flame holding event has occurred or is occurring, the amplitude of a given dynamic amplitude DA measurement is compared to a dynamic amplitude threshold TL stored in memory (e.g., memory 204). As an example shown in FIGS. 1 and 2 , a profile of turbine engine 100 is stored in memory, the profile including a dynamic amplitude threshold TL corresponding to a flame holding event for turbine engine 100. Stated another way, when considering the spectral energy amplitude A2, amplitudes occurring below the dynamic amplitude threshold TL correspond to a non-flame holding event, and amplitudes occurring above the dynamic amplitude threshold TL correspond to a flame holding event. It should be understood that different turbine engines may have different profiles and different dynamic amplitude thresholds. The profile for a turbine engine may be empirically determined in a controlled or laboratory setting and pre-loaded into local memory 204. In an embodiment in which detection system 250 is retrofitted to an existing turbine engine, the profile may be loaded into local memory 204.

[0038] Processor 202 determines that a flame holding condition is occurring by comparing spectral energy amplitude A2 to a dynamic amplitude threshold TL of a profile of turbine engine 100. In some embodiments, processor 202 also compares the duration that spectral energy amplitude A2 exceeds dynamic amplitude threshold TL to a minimum duration for a flame holding occurrence. By way of example, if spectral energy amplitude A2 exceeds dynamic amplitude threshold TL for less than a predetermined minimum amount of time, processor 202 determines that a flame holding condition is not occurring.

[0039] Thus, processor 202 can determine whether a flame holding condition has occurred or is occurring by comparing the spectral energy amplitude A2 to a profile stored in memory 204. Processor 202 can send a signal to network 210 via communication interface 206 to alert a user that a flame holding event is occurring or has occurred. In some embodiments, processor 202 can store the date and time of the flame holding occurrence in memory 204.

[0040] In some embodiments, processor 202 is programmed to perform the conversion every 4 Hz. Thus, once period P has elapsed, processor 202 can mitigate the flame holding condition in real time. In some embodiments, processor 202 is programmed to perform the check every 10 seconds (as described in more detail below with respect to method 300 shown in FIG. 4). In some embodiments, processor 202 is configured to perform the check every 2 seconds.

[0041] In some embodiments, detection system 250, and more specifically processor 202, can mitigate the flame holding condition in real time, thus stopping the flame holding from occurring. If processor 202 detects that a flame holding condition is occurring, processor 202 can instruct communication interface 206 to decrease the hydrogen gas concentration of the fuel mixture (e.g., from the second hydrogen gas concentration to the first hydrogen gas concentration, or to any desired value between the first and second concentrations) until flame holding stops. In some embodiments, communication interface 206 is coupled to mixing valve 172 and multiple mixing fuel valves 152 (one of which is shown in FIG. 1 ). As a result of the rapid detection and mitigation capabilities of this detection system 250, turbine engine 100 can safely and continuously operate within an extended flame holding margin window using the second hydrogen gas concentration, resulting in increased efficiency, reduced emissions, and reduced audible noise, without the risk of a flame holding event that would stall or damage turbine engine 100.

[0042] 7 illustrates a flowchart of an exemplary method 300 for use in detecting and mitigating flame holding within a turbine engine 100. Referring to the components illustrated in FIGS. 1-6 , in an exemplary embodiment, the method 300 includes disposing 302 at least one dynamic pressure sensor 208 within at least one combustor 124 of the turbine engine 100, the at least one dynamic pressure sensor 208 being communicatively coupled to the processor 202. The method 300 further includes measuring 304 dynamic pressure data DP by the at least one dynamic pressure sensor 208, and in some embodiments, storing the dynamic pressure data DP in the local memory 204. The method 300 also includes transforming 306, by the processor 202, the dynamic pressure data DP in the time domain through mathematical integration to obtain a frequency domain spectral energy amplitude A2 of the dynamic pressure data in the frequency domain. The method 300 further includes comparing 308, by the processor 202, the frequency domain spectral energy amplitude to a profile stored in the local memory 204 to determine whether the frequency domain spectral energy amplitude exceeds a predetermined dynamic amplitude threshold TL of the profile, where exceeding the dynamic amplitude threshold TL indicates flame holding. The method 300 further includes mitigating 310 the flame holding condition in the turbine engine 100. In some embodiments, mitigating the flame holding condition includes reducing 312, by the processor 202, the hydrogen gas concentration of the fuel mixture from the second hydrogen gas concentration to the first hydrogen gas concentration, or to a desired value between the first and second hydrogen gas concentrations, until flame holding ceases. To mitigate flame holding, the processor 202 can send a signal to the mixing valve 172 to adjust the hydrogen gas concentration supplied to the mixed fuel supply 150 and / or send a signal to one or more multiple mixing fuel valves 152 coupled to each combustor 124 to redistribute the mixed fuel among the fuel injectors 126 of the combustors 124.

[0043] 8 illustrates a flowchart of an exemplary method 400 for operating a turbine engine with reduced emissions and reduced audible noise. Referring to FIGS. 1-6 , the exemplary method 400 includes supplying a fuel mixture having a second hydrogen gas concentration to at least one combustor 124 of the turbine engine 100. The method 400 further includes measuring 404 dynamic pressure data DP within the turbine engine combustor via at least one dynamic pressure sensor 208 within the at least one combustor 124, and, in some embodiments, storing the dynamic pressure data DP in the local memory 204. The at least one dynamic pressure sensor 208 is communicatively coupled to the processor 202. The method 400 further includes transforming 406, by the processor 202, the dynamic pressure data DP in the time domain via mathematical integration to obtain a frequency-domain spectral energy amplitude of the dynamic pressure data in the frequency domain. The method 400 further includes comparing 408, by the processor 202, the frequency domain spectral energy amplitude A2 to a profile stored in the local memory 204 to determine whether the frequency domain spectral energy amplitude A2 exceeds a predetermined dynamic amplitude threshold TL of the profile, where exceeding the dynamic amplitude threshold TL indicates flame holding. The method 400 further includes mitigating 410 the flame holding condition in the turbine engine 100. In some embodiments, mitigating the flame holding condition includes reducing 412, by the processor 202, the hydrogen gas concentration of the fuel mixture from the second hydrogen gas concentration to the first hydrogen gas concentration, or to a desired value between the first and second hydrogen gas concentrations, until flame holding ceases. To mitigate flame holding, the processor 202 may send a signal to the mixing valve 172 to adjust the hydrogen gas concentration in the fuel mixture supplied to the mixed fuel supply 150 and / or may send a signal to one or more of the multiple mixing fuel valves 152 coupled to each combustor 124 to redistribute the mixed fuel among the fuel injectors 126 of the combustors 124.

[0044] In some embodiments, method 400 also includes increasing 414, by processor 202, the hydrogen gas concentration of the fuel mixture from the first hydrogen gas concentration to a second hydrogen gas concentration when the flame holding condition is alleviated, thereby causing turbine engine 100 to return to operation within the extended flame holding margin window with reduced emissions and reduced audible noise. To return to operation within the extended flame holding margin window, processor 202 may send a signal to mixing valve 172 to increase the hydrogen gas concentration in the fuel mixture delivered to mixed fuel supply 150.

[0045] The computer systems discussed herein may include additional, less, or alternative functionality, including those discussed elsewhere herein. The computer systems discussed herein may include or be implemented via computer-executable instructions stored on a non-transitory computer-readable medium or media.

[0046] Exemplary embodiments of methods for detecting, controlling, and mitigating flame holding occurrences are described above in detail. The methods are not limited to use with the specific turbine embodiments described herein; rather, the methods may be utilized separately and independently of the other components described herein. For example, the methods may be used with any utility, industrial, or mechanically driven turbine. Furthermore, the present invention is not limited to the method embodiments described in detail above. Rather, other variations of the methods may be utilized within the spirit and scope of the claims.

[0047] In each embodiment, the above-described methods and systems for detecting and mitigating a flame holding condition enable a turbine engine to operate at a higher hydrogen concentration while preventing engine flame holding. Furthermore, the methods and systems can determine a flame holding condition in a turbine engine while operating at a higher hydrogen concentration in real time during continuous operation of the turbine engine. The methods and systems can be applied to existing turbine engines in the field by programming a profile including threshold limits and the described instructions into the existing turbine engine's processor to enable the existing turbine engine to detect and mitigate flame holding. More specifically, the processor can be programmed to check for flame holding events (as described in method 300 of FIG. 7 ) without additional components or modifications to the turbine engine.

[0048] Any logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desired results. Additionally, other steps may be provided or steps may be eliminated from the described flows, and other components may be added to or removed from the described systems. Accordingly, other embodiments are within the scope of the following claims.

[0049] It will be understood that the above embodiments described in particular detail are merely examples or possible embodiments, and that there are many other combinations, additions, or alternatives that may be included.

[0050] Moreover, the particular naming of components, term capitalization, attributes, data structures, or any other programming or structural aspects are not required or important, and mechanisms implementing the present disclosure or its features may have different names, formats, or protocols. Furthermore, the system may be implemented through a combination of hardware and software, as described, or entirely within hardware elements. Also, the particular division of functionality among various system components described herein is merely exemplary and not required. Rather, functions performed by a single system component may instead be performed by multiple components, and functions performed by multiple components may instead be performed by a single component.

[0051] As used herein throughout the present specification and claims, approximation language may be applied to modify any quantitative expression that may be permissibly varied without resulting in a change in the basic function to which it relates. Thus, values ​​modified by one or more terms such as "about" and "substantially" should not be limited to the exact value specified. In at least some instances, approximation language may correspond to the precision of an instrument for measuring the value. Here, and throughout the present specification and claims, where range limitations can be combined and / or interchanged, such ranges are identified and include all subranges contained therein, unless the context or language indicates otherwise.

[0052] Various changes, modifications, and alterations in the teachings of this disclosure may occur to those skilled in the art without departing from its intended spirit and scope, and this disclosure is intended to cover all such changes and modifications.

[0053] This specification uses examples to explain the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any device or system, and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims.

[0054] While the systems and methods have been described in terms of various specific embodiments, those skilled in the art will recognize that the subject technology can be practiced with modification within the spirit and scope of the claims. The systems and methods can be defined by the following exemplary clauses.

[0055] According to a first aspect, a method for detecting flame holding in at least one combustor of a turbine engine includes measuring dynamic pressure within at least one combustor of the turbine engine; converting the dynamic pressure data to a frequency domain spectral energy amplitude associated with the dynamic pressure data; and comparing the frequency domain spectral energy amplitude to a dynamic amplitude threshold to determine whether the spectral energy amplitude exceeds the dynamic amplitude threshold, wherein a spectral energy amplitude exceeding the dynamic amplitude threshold indicates the occurrence of flame holding.

[0056] In accordance with the above aspect, the method further includes mitigating the flame holding condition in the at least one combustor when a flame holding occurrence is determined.

[0057] According to any of the above-described aspects, mitigating the flame holding condition in the at least one combustor includes adjusting a hydrogen gas concentration of a fuel mixture delivered to the at least one combustor by a fuel injection system from a second hydrogen gas concentration to a first hydrogen gas concentration, the second hydrogen gas concentration being greater than the first hydrogen gas concentration.

[0058] According to any of the above-described aspects, a standard operating window of the turbine engine is defined by supplying a fuel mixture having a first hydrogen gas concentration to at least one combustor, and an extended flame-holding margin window of the turbine engine is defined by supplying a fuel mixture having a second hydrogen gas concentration to the at least one combustor.

[0059] According to any of the above aspects, the processor is programmed to cause a mixing valve coupled to the hydrogen fuel source and the natural gas fuel source to selectively vary a hydrogen gas concentration in the fuel mixture, and a mixed fuel source downstream of the mixing valve supplies the fuel mixture to fuel injectors of at least one combustor of the turbine engine.

[0060] According to any of the above-described aspects, mitigating the flame holding condition of the at least one combustor includes decreasing at least one of a fuel injector pressure ratio, a velocity of the fuel mixture, and a temperature of the fuel mixture delivered to the at least one combustor.

[0061] According to any of the above aspects, the method further includes positioning at least one dynamic pressure sensor in the at least one combustor to measure a dynamic pressure in the respective combustor, the at least one dynamic pressure sensor coupled to the processor.

[0062] According to any of the above aspects, the method further includes storing the dynamic pressure data in a local memory, the local memory coupled to the processor.

[0063] According to any of the above aspects, the dynamic pressure data is converted to frequency domain spectral energy amplitude by performing a mathematical integration of the dynamic pressure data.

[0064] According to any of the above aspects, the mathematical integration is selected from the group consisting of a Fourier transform, a fast Fourier transform, a discrete Fourier transform, and a numerical calculation.

[0065] According to any of the above aspects, the dynamic amplitude threshold is stored in a local memory, the local memory being coupled to the processor.

[0066] According to any of the above aspects, the dynamic amplitude threshold corresponds to a flame holding occurrence in a turbine engine.

[0067] According to any of the above aspects, the dynamic pressure data is in the time domain and the spectral energy amplitude is in the frequency domain.

[0068] According to a second aspect of the present disclosure, a method for operating a turbine engine with reduced emissions and reduced audible noise includes supplying a fuel mixture having a second hydrogen gas concentration to at least one combustor of the turbine engine, the second hydrogen gas concentration defining an extended flame-holding margin window for the turbine engine, the extended flame-holding margin window resulting in reduced emissions and reduced audible noise for the turbine engine; measuring dynamic pressure data within the at least one combustor of the turbine engine; converting the dynamic pressure data to a frequency domain spectral energy amplitude associated with the dynamic pressure data; comparing the spectral energy amplitude to a dynamic amplitude threshold to determine whether the spectral energy amplitude exceeds the dynamic amplitude threshold, wherein a spectral energy amplitude exceeding the dynamic amplitude threshold indicates a flame-holding occurrence; and mitigating a flame-holding condition in the at least one combustor by adjusting a hydrogen gas concentration of the fuel mixture supplied to the at least one combustor from the second hydrogen gas concentration to a first hydrogen gas concentration, the second hydrogen gas concentration being higher than the first hydrogen gas concentration, the first hydrogen gas concentration defining a normal operating window.

[0069] According to a second aspect, mitigating the flame holding condition of the at least one combustor includes reducing at least one of a fuel injector pressure ratio, a velocity of the fuel mixture, and a temperature of the fuel mixture delivered to the turbine engine.

[0070] According to a second aspect and any intervening aspect, the method further includes increasing the hydrogen gas concentration of the fuel mixture from the first hydrogen gas concentration to a second hydrogen gas concentration after the flame holding condition is alleviated.

[0071] According to a third aspect of the present disclosure, a system that facilitates operating at least one combustor of a turbine engine within a flame-holding margin is provided, the system including: a fuel injection system coupled in flow communication with a mixed fuel supply source for supplying a fuel mixture to at least one fuel injector in the at least one combustor of the turbine engine, the fuel mixture having a hydrogen gas concentration adjustable from a first hydrogen gas concentration to a second hydrogen gas concentration, the second hydrogen gas concentration being higher than the first hydrogen gas concentration; and a detection system including a processor and a plurality of dynamic pressure sensors, the processor supplying the fuel mixture having the second hydrogen gas concentration to the turbine engine, the second hydrogen gas concentration defining an extended flame-holding margin window for the turbine engine, the extended flame-holding margin window being extended when the turbine engine is operating at the first hydrogen gas concentration. the turbine engine is programmed to: receive dynamic pressure data measured within at least one combustor of the turbine engine from one or more of a plurality of dynamic pressure sensors; convert the dynamic pressure data into a frequency domain spectral energy amplitude associated with the dynamic pressure data; compare the spectral energy amplitude to a dynamic amplitude threshold to determine whether the spectral energy amplitude exceeds the dynamic amplitude threshold, wherein a spectral energy amplitude exceeding the dynamic amplitude threshold indicates flame holding; and reduce a hydrogen gas concentration of the fuel mixture from a second hydrogen gas concentration to a first hydrogen gas concentration, the first hydrogen gas concentration defining a standard operating window with a reduced likelihood of flame holding compared to the expanded flame holding margin window.

[0072] According to a third aspect, the processor is further programmed to control a mixing valve coupled to the hydrogen gas source and the natural gas source to selectively vary the hydrogen gas concentration of the fuel mixture, the mixing valve being upstream of a mixed fuel source that supplies operating fuel to fuel injectors of at least one combustor of the turbine engine.

[0073] According to a third aspect and any intervening aspect, the processor is further programmed to mitigate the flame holding condition of the at least one combustor by one or more of adjusting the hydrogen gas concentration supplied to the mixed fuel supply, redistributing the mixed fuel among fuel injectors of the one or more combustors, and decreasing at least one of a fuel injector pressure ratio, a velocity of the fuel mixture, and a temperature of the fuel mixture supplied to the at least one combustor.

[0074] According to the third aspect and any intervening aspect, the dynamic pressure data is converted to frequency domain amplitude by performing a mathematical integration of the dynamic pressure data. [Explanation of symbols]

[0075] 100 turbine engine 124 Combustor 126 Fuel Injector 150 Mixed Fuel Source 154 Fuel injection system 160 Hydrogen Fuel Source 170 Natural Gas Fuel Sources 172 Mixing valve 202 processors 204 Local Memory 208 Dynamic pressure sensor 250 Detection System A2 Frequency domain spectral energy amplitude DP dynamic pressure data TL Dynamic Amplitude Threshold

Claims

1. A method for detecting flame holding in at least one combustor (124) of a turbine engine (100), comprising: Measuring dynamic pressure within the at least one combustor (124) of the turbine engine (100); converting the dynamic pressure data (DP) into a frequency domain spectral energy amplitude (A2) associated with said dynamic pressure data (DP); comparing the frequency domain spectral energy amplitude (A2) with a dynamic amplitude threshold (TL) to determine whether the spectral energy amplitude (A2) exceeds the dynamic amplitude threshold (TL), wherein the spectral energy amplitude (A2) exceeding the dynamic amplitude threshold (TL) indicates a flame holding occurrence; A method comprising:

2. The method of claim 1, further comprising mitigating a flame holding condition in the at least one combustor (124) when a flame holding occurrence is determined.

3. 3. The method of claim 2, wherein mitigating the flame holding condition in the at least one combustor comprises adjusting a hydrogen gas concentration of a fuel mixture supplied to the at least one combustor by a fuel injection system from a second hydrogen gas concentration to a first hydrogen gas concentration, the second hydrogen gas concentration being greater than the first hydrogen gas concentration.

4. 4. The method of claim 3, wherein a normal operating window of the turbine engine is defined by supplying the fuel mixture having the first hydrogen gas concentration to the at least one combustor, and an extended flame-holding margin window of the turbine engine is defined by supplying the fuel mixture having the second hydrogen gas concentration to the at least one combustor.

5. 4. The method of claim 3, wherein the processor is programmed to cause a mixing valve coupled to a hydrogen fuel source and a natural gas fuel source to selectively vary the hydrogen gas concentration of the fuel mixture, and a mixed fuel source downstream of the mixing valve delivers the fuel mixture to a fuel injector of the at least one combustor of the turbine engine.

6. 4. The method of claim 3, wherein mitigating a flame holding condition in the at least one combustor comprises reducing at least one of a fuel injector pressure ratio, a velocity of the fuel mixture, and a temperature of the fuel mixture supplied to the at least one combustor.

7. 2. The method of claim 1, further comprising positioning at least one dynamic pressure sensor in the at least one combustor to measure dynamic pressure in the respective combustor, the at least one dynamic pressure sensor coupled to a processor.

8. The method of claim 7, further comprising storing the dynamic pressure data (DP) in a local memory (204), the local memory (204) coupled to the processor (202).

9. 2. The method of claim 1, wherein the dynamic pressure data (DP) is converted to the frequency domain spectral energy amplitude (A2) by performing a mathematical integration of the dynamic pressure data (DP).

10. 10. The method of claim 9, wherein the mathematical integration is selected from the group consisting of a Fourier transform, a fast Fourier transform, a discrete Fourier transform, and a numerical calculation.

11. The method of claim 1 , wherein the dynamic amplitude threshold (TL) is stored in a local memory (204), the local memory (204) being connected to a processor (202).

12. The method of claim 11 , wherein the dynamic amplitude threshold (TL) corresponds to a flameholding occurrence in the turbine engine (100).

13. 2. The method of claim 1, wherein the dynamic pressure data (DP) is in the time domain and the spectral energy amplitude (A2) is in the frequency domain.

14. A method of operating a turbine engine (100) with reduced emissions and reduced audible noise, comprising: supplying a fuel mixture having a second hydrogen gas concentration to at least one combustor of the turbine engine, the second hydrogen gas concentration defining an extended flame-holding margin window for the turbine engine, the extended flame-holding margin window resulting in the reduced emissions and reduced audible noise of the turbine engine; Measuring dynamic pressure data (DP) within at least one combustor (124) of the turbine engine (100); converting the dynamic pressure data (DP) into a frequency domain spectral energy amplitude (A2) associated with the dynamic pressure data (DP); comparing the spectral energy amplitude (A2) with a dynamic amplitude threshold (TL) to determine whether the spectral energy amplitude (A2) exceeds the dynamic amplitude threshold (TL), wherein the spectral energy amplitude (A2) exceeding the dynamic amplitude threshold (TL) indicates a flame holding occurrence; mitigating a flame holding condition in the at least one combustor (124) by adjusting the hydrogen gas concentration of the fuel mixture supplied to the at least one combustor (124) from the second hydrogen gas concentration to a first hydrogen gas concentration, the second hydrogen gas concentration being greater than the first hydrogen gas concentration, and the first hydrogen gas concentration defining a normal operating window; A method comprising:

15. 15. The method of claim 14, wherein mitigating a flame holding condition in the at least one combustor comprises reducing at least one of a fuel injector pressure ratio, a velocity of the fuel mixture, and a temperature of the fuel mixture delivered to the turbine engine.

16. 15. The method of claim 14, further comprising increasing the hydrogen gas concentration of the fuel mixture from the first hydrogen gas concentration to the second hydrogen gas concentration after the flame holding condition is alleviated.

17. 1. A system for facilitating operation of at least one combustor (124) of a turbine engine (100) within a flame-holding margin, the system (250) comprising: a fuel injection system coupled in flow communication with the mixed fuel supply source for supplying a fuel mixture to at least one fuel injector in the at least one combustor of the turbine engine, the fuel mixture having a hydrogen gas concentration adjustable from a first hydrogen gas concentration to a second hydrogen gas concentration, the second hydrogen gas concentration being greater than the first hydrogen gas concentration; a detection system (250) including a processor (202) and a plurality of dynamic pressure sensors (208), wherein the processor (202) supplying the fuel mixture having the second hydrogen gas concentration to the turbine engine, the second hydrogen gas concentration defining an extended flame-holding margin window for the turbine engine, the extended flame-holding margin window enabling the turbine engine to operate with higher mechanical power output, reduced emissions, and reduced audible noise compared to the turbine engine operating with the first hydrogen gas concentration; receiving dynamic pressure data (DP) measured within the at least one combustor (124) of the turbine engine (100) from one or more of the plurality of dynamic pressure sensors (208); converting the dynamic pressure data (DP) into a frequency domain spectral energy amplitude (A2) associated with the dynamic pressure data (DP); comparing the spectral energy amplitude (A2) with a dynamic amplitude threshold (TL) to determine whether the spectral energy amplitude (A2) exceeds the dynamic amplitude threshold (TL), wherein a spectral energy amplitude (A2) exceeding the dynamic amplitude threshold (TL) indicates a flame holding event; decreasing the hydrogen gas concentration of the fuel mixture from the second hydrogen gas concentration to the first hydrogen gas concentration, the first hydrogen gas concentration defining a standard operating window with a reduced likelihood of flame holding compared to the extended flame holding margin window; The system (250) is programmed to:

18. 18. The system of claim 17, wherein the processor is further programmed to control a mixing valve coupled to a hydrogen gas source and a natural gas source to selectively vary the hydrogen gas concentration of the fuel mixture, the mixing valve being upstream of a mixed fuel source that supplies operating fuel to the fuel injectors of the at least one combustor of the turbine engine.

19. 20. The system of claim 17, wherein the processor is further programmed to mitigate a flame holding condition in the at least one combustor by one or more of: adjusting the hydrogen gas concentration supplied to the mixed fuel supply; redistributing the mixed fuel among fuel injectors of the one or more combustors; and reducing at least one of a fuel injector pressure ratio supplied to the at least one combustor, a velocity of the fuel mixture, and a temperature of the fuel mixture.

20. 20. The system (250) of claim 17, wherein the dynamic pressure data (DP) is converted to frequency domain amplitude by performing a mathematical integration of the dynamic pressure data (DP).

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