Impact of Turbulence on Mechanisms of Combustion Instability
Overview
Combustion instability is an issue that affects many critical power and propulsion technologies, including jet engines, power-generation gas turbines, rockets, boilers, and process furnaces. Significant questions remain about how turbulence alters flame behavior during instability. In particular, in high-performance engines, does the turbulence/flame interaction change the instability feedback mechanisms and do the present numerical models include the correct physics? This work addresses these questions using a systematic experimental approach to examine various key aspects of combustion instability. Advanced laser diagnostics will be used to image the flowfield and the flame, unlocking the coupling between turbulence and the instability feedback loop.
The technical goal of this project is to understand the impact of turbulence on three critical components of the thermoacoustic feedback loop: the hydrodynamic instability of the flowfield that determines the susceptibility of the flow to external disturbances; the coupling mechanisms that drive heat release rate oscillations; and the mechanism by which these disturbances create heat release rate oscillations in non-flamelet regimes. This systematic approach uses theory-based experimental design to probe the ways in which turbulence impacts flow stability, coupling-mechanism physics, and flame behavior within the framework of combustion instability.
In collaboration with Drs. Santosh Hemchandra – Indian Institute of Science – Bangalore and Isaac Boxx – DLR, German Aerospace Center, Stuttgart, Germany
Publications
Clark, C., Torres Hernandez, C., Markle, S., Colborn, J., O’Connor, J. (2024) “Effect of centerbody temperature on blowoff limits of a swirl-stabilized flame.” Spring Technical Meeting of the Eastern States Section of the Combustion Institute. Author accepted pre-print available here.
Rivera, I., Birkbeck, C., Torres Hernandez, C., Subasic, N., Karmarkar, A. , Rodriguez Camacho, J., O’Connor, J. (2024), “Swirl number effects on the blowoff limits of swirl-stabilized flames.” Spring Technical Meeting of the Eastern States Section of the Combustion Institute. Author accepted pre-print available here.
Birkbeck, C., Rivera, I., Torres Hernandez, C., Rodriguez Camacho, J., O’Connor, J. (2024) “The effect of centerbody geometry on lean blowoff in a swirl-stabilized flame.” Spring Technical Meeting of the Eastern States Section of the Combustion Institute. Author accepted pre-print available here.
Karmarkar, A., & O’Connor, J. (2023). “Impact of turbulence on the coherent heat release response of acoustically excited rod-stabilized flames.” ASME Turbo Expo. Author accepted pre-print available here.
Karmarkar, A. & O’Connor, J. (2023) “Interaction between coherent and turbulent oscillations in non-reacting and reacting wake flows,” Journal of Fluid Mechanics, 963, p. A13. (open access)
O’Connor, J. (2022) “The Role of Hydrodynamic Instability in Thermoacoustic Oscillations in Gas Turbine Combustors,” Proceedings of the Combustion Institute, 39(4), p. 4583-4610. Author accepted pre-print available here.
Karmarkar, A., O’Connor, J. (2022) “Impact of turbulence on flame brush development of acoustically excited rod-stabilized flames,” Proceedings of the Combustion Institute, 39(2), p. 2139-2148. Author accepted pre-print available here.
Karmarkar, A., Gupta, S., Boxx, I., Hemchandra, S., O’Connor, J. (2022) “Impact of precessing vortex core dynamics on the thermoacoustic instabilities in a swirl stabilized combustor.” Journal of Fluid Mechanics, 946: p. A36 (open access)
Karmarkar, A., & O’Connor, J. (2021). “Impact of turbulence on the response of flames to external coherent excitation.” Bulletin of the American Physical Society, 66.
Karmarkar, A., Boxx, I., & O’Connor, J. (2021) “Relative Effects of Velocity-and Mixture-Coupling in a Thermoacoustically Unstable, Partially-Premixed Flame.” Journal of Engineering for Gas Turbines and Power, accepted. Accepted author pre-print available here.
Karmarkar, A., Tyagi, A., Hemchandra, S., & O’Connor, J. (2020) “Impact of turbulence on the coherent flame dynamics in a bluff-body stabilized flame,” Proceedings of the Combustion Institute, 38(2), p. 3067-3075. Accepted author pre-print available here and supplemental material.
Karmarkar, A., Yoon, J., Boxx, I., and O’Connor, J., (2020) “Impact of air splits in a dual-stream swirler on fuel-air mixing and thermoacoustic instability in a swirl stabilized high pressure combustor,” Spring Technical Meeting of the Eastern States Section of the Combustion Institute, Columbia, SC. Author version here.
Karmarkar, A., Frederick, M. Clees, S., Mason, D., O’Connor, J., (2019) “Role of turbulence in precessing vortex core dynamics,” ASME Turbo Expo, Phoenix, AZ. Accepted author pre-print available here.
A Fundamental Framework for the Robust Multivariable Stabilization of Time-Delayed Acoustic-Flame Interaction Dynamics, with Application to Gas Turbines
Overview
This project is conducted to attenuate the pressure oscillations associated with instability in combustion systems such as gas turbine, rockets, industrial process furnaces, and boilers. The need for controlling combustion instabilities is growing rapidly as society pushes for combustion systems with reduced emissions and increased ability to respond to fluctuating power demands. Gas turbines play an important role in ensuring the resilience of the power grid, where their ability to respond to both slow and rapid demand fluctuations enables them to provide a broad portfolio of ancillary grid services. However, the intermittent, transient operation of these grid-tied generators has not been traditionally considered in their design, which can lead to high-amplitude instability during the above operations. From the study on the instability onset of a laboratory combustor undergoing transient operation[1], the dramatic increase in combustion-related pressure oscillations by almost an order of magnitude, in less than half a second, highlights the degree to which combustion instability can be disruptive and potentially damaging in gas turbine systems.
The goal of the research is firstly to furnish a fundamental framework for the robust, multivariable, combined passive/active attenuation of combustion instability in a broad range of applications. This framework will take into account the prominent role played by transport delay dynamics in combustion instability, as well as the degree to which uncertainties in factors such as fuel composition and ambient temperature/pressure/humidity affect these delay dynamics. The second goal is to demonstrate the above fundamental framework using a flexible combustion rig as an experimental validation.
In collaboration with Dr. Hosam Fathy, University of Maryland
Publications
Chen, X., O’Connor, J., & Fathy, H. (2021). “Heat Release Rate Estimation Using Multiple Non-Minimum Phase Sensor Measurements in a One-dimensional Combustor.” IFAC-PapersOnLine, 54(20), 723-728. Author accepted pre-print here.
Chen, X., Hemchandra, S., Fathy, H., & O’Connor, J. (2021). “Linear control of thermoacoustic oscillations with flame dynamics modeled by a level-set method.” Combustion and Flame, 237, 111686. Author accepted pre-print here. Supplementary material here.
Chen, X., O’Connor, J., Fathy, H. (2021) “Optimizing Thermoacoustic Characterization Experiments for Identifiability Improves Both Parameter Estimation Accuracy and Closed-Loop Controller Robustness Guarantees,” Combustion Science and Technology, 194(11), 2186-2211. Accepted author pre-print available here.
Chen, X., Fathy, H., & O’Connor, J. (2020). “Impact of Sensor Placement on Mode Observability and LQG Control of a Thermoacoustic System.” IFAC-V 2020. Accepted author pre-print available here.
Chen, X., Dillen, E., Fathy, H., O’Connor, J., (2019) “Optimizing the design of a Rijke tube experiment for combustion stability model identifiability,” American Control Conference, Philadelphia, PA. Accepted author pre-print available here.
Understanding Instability Suppression using Simultaneous Flow and Flame Measurements
Overview
The objective of this research is to quantify the effect of piloting on instantaneous flame dynamics to understand the mechanism of instability suppression. Pilot flames are small flames, typically located in the center of a main flame or in a ring formation around the base of the main flame, that aid in static flame stabilization and instability suppression. The mechanism by which this commonly used method of passive instability suppression works is still unclear. The goal of this work is to understand the instability suppress mechanisms by investigating flame dynamics using a range of high-speed imaging and laser diagnostics as well as thermoacoustic modeling.
Publications
Rodriguez Camacho, J., Akiki, M., Blust, J., & O’Connor, J. (2024). “Effect of inert species on the static and dynamic stability of a piloted, swirl-stabilized flame.” Journal of Engineering for Gas Turbines and Power. 146(6), p. 061021. Author accepted pre-print available here.
Doleiden, D., Karmarkar, A., O’Connor, J., Blust, J. (2022) “Impact of Piloting on the Static and Dynamic Stability of Swirl-Stabilized Flames,” ASME Turbo Expo, GT2022-80226. Author accepted pre-print here.
Li, J., Kwon, H., Seksinsky, D., Doleiden, D., Xuan, Y., O’Connor, J., Blust, J., Akiki, M., (2021) “Describing the Mechanism of Instability Suppression Using a Central Pilot Flame With Coupled Experiments and Simulations” in Journal of Engineering for Gas Turbines and Power, 144(1), p. 011015. Author accepted pre-print here.
Understanding Transient Combustion Phenomena in Low-NOx Gas Turbines
Overview
Combustion instability is a major issue that impacts the operability of modern, lean-premixed gas turbine engines. Combustion instability occurs when heat release rate fluctuations couple with combustor acoustics in a feedback loop; this manifests as large amplitude pressure oscillations. These pressure oscillations are undesirable because they increase the emissions from the engine, and in the worst-case, cause catastrophic hardware failure from rapid fatigue loading. One way to suppress combustion instability is to redistribute the fuel un-evenly through different nozzles while maintaining the same overall fuel flow rate. This un-even distribution of fuel is called “fuel-staging,” and is widely used in industry for instability suppression. While fuel staging is successful at suppressing instabilities, the mechanism of its operation is not well-researched. Furthermore, gas turbine engines in the field must undergo transients in load as the power demands change throughout the day, and it is not well-understood how these transients in load (and by extension fuel staging) affect combustion instability. The goal of the current work is twofold: One, to understand the mechanisms by which fuel staging suppresses instability and two, to understand how transients in fuel staging affect the instability. Pressure measurements, high-speed flame images, and laser-induced fluorescence are used to capture the combustor and flame dynamics at different operating points.
DOE announcement: https://energy.gov/fe/articles/nine-projects-selected-funding-through-university-turbine-systems-research-program
Publications
Strollo, J., Peluso, S., O’Connor, J. (2021) “Effect of hydrogen on steady-state and transient combustion instability characteristics,” Journal of Engineering for Gas Turbines and Power, 143(7), p. 071023. Accepted author pre-print available here.
Howie, A., Doleiden, D., Peluso, S., & O’Connor, J.(2021) “The Effect of the Degree of Premixedness on Self-Excited Combustion Instability.” Journal of Engineering for Gas Turbines and Power, 143(7), p. 071024. Accepted author pre-print available here.
Bhattacharya, C., O’Connor, J., & Ray, A. (2020) “Data-driven Detection and Early Prediction of Thermoacoustic Instability in a Multi-nozzle Combustor,” Combustion Science and Technology, in press. Accepted author pre-print available here.
Westfall, S., Sekulich, O., Culler, W., Peluso, S., & O’Connor, J. “Quantification of Variation in Combustion Instability Amplitude in a Multi-Nozzle Can Combustor.” ASME Turbo Expo, London, England. Accepted author pre-print available here.
Doleiden, D., Culler, W., Tyagi, A., Peluso, S., O’Connor, J., (2019) “Flame edge dynamics and interaction in a multi-nozzle can combustor with fuel staging,” Journal of Engineering for Gas Turbines and Power, 141(10), p. 101009. Accepted author pre-print available here.
Doleiden, D., Culler, W., Tyagi, A., Peluso, S., O’Connor, J., (2019) “Flame edge dynamics and interaction in a multi-nozzle can combustor with fuel staging,” ASME Turbo Expo, Phoenix, AZ. Accepted author pre-print available here.
Culler, W., Chen, X., Samarasinghe, J., Peluso, S., Santavicca, D., O’Connor, J., (2018) “The effect of variable fuel staging transients on self-excited instabilities in a multiple-nozzle combustor,” Combustion and Flame, 194, p. 472-484. Accepted author pre-print available here.
Culler, W., Chen, X., Peluso, S., Santavicca, D., O’Connor, J., Noble, D., (2018) “Comparison of center nozzle staging to outer nozzle staging in a multi-flame combustor,” ASME Turbo Expo, Oslo, Norway. Accepted author pre-print available here.
Chen, X., Culler, W., Peluso, S., Santavicca, D., O’Connor, J., (2018) “Comparison of equivalence ratio transients on combustion instability in single-nozzle and multi-nozzle combustors,” ASME Turbo Expo, Oslo, Norway. Accepted author pre-print available here.
Chen, X., Culler, W., Peluso, S., Santavicca, D., O’Connor, J., (2018) “Effects of equivalence ratio transient duration on self-excited combustion instability time scales in a single-nozzle combustor,” Spring Technical Meeting of the Eastern States Section of the Combustion Institute, State College, PA. Author version available here.
Sekulich, O., Culler, W., O’Connor, J., (2018) “The effect of non-axisymmetric fuel staging on flame structure in a multiple-nozzle model gas turbine combustor,” Spring Technical Meeting of the Eastern States Section of the Combustion Institute, State College, PA. Author version available here.
Samarasinghe, J., Culler, W., Quay, B., Santavicca, D. A., O’Connor, J. (2017) “The effect of fuel staging on the structure and instability characteristics of swirl-stabilized flames in a lean premixed multi-nozzle can combustor.” Journal of Engineering for Gas Turbines and Power, 139(12), 121504. Accepted author pre-print available here.
Culler, W., Samarasinghe, J., Quay, B., Santavicca, D. A., O’Connor, J. (2017) “The effect of transient fuel staging on self-excited instabilities in a multi-nozzle model gas turbine combustor,” ASME Turbo Expo, Charlotte, NC. Accepted author pre-print available here.
O’Connor, J., S. Hemchandra, T. Lieuwen, “Combustion Instabilities in Lean Premixed Systems.” Ed. D. Dunn-Rankin and P. Therkelsen, Lean Combustion: Technology and Control, Second Edition.
O’Connor, J., V. Acharya, T. Lieuwen, (2015) “Transverse Combustion Instabilities: Acoustic, Fluid Mechanic, and Flame Processes,” Progress in Energy and Combustion Science, 49, p. 1-39. Accepted author pre-print available here.