Combustion dynamics of turbulent swirl flames with hydrogen addition
Lead Research Organisation:
University College London
Department Name: Mechanical Engineering
Abstract
Combustion instabilities represent one of the most serious problems hindering the development of low-emission aero- and industrial- gas turbine combustors. In order to achieve efficient, low-emissions performance fuel-lean and preferably premixed operating conditions are necessary. However, these lean combustors have the drawback of being particularly susceptible to thermo-acoustic instability. These instabilities are characterised by strong pressure oscillations in the combustion chamber due to a complex interaction between thermo-acoustic and fluid-dynamic processes. When the pressure or velocity oscillations couple favourably with the unsteady heat release, large-amplitude self-sustained oscillation may result. These high amplitude oscillations can have a detrimental effect on combustor performance and may cause catastrophic failure of the system. Lean premix concept is increasingly adopted by gas turbine engine manufacturers to reduce emissions and increase fuel economy. Although fuel lean conditions reduce NOx emissions by decreasing the flame temperature, lean flames are particularly susceptible to combustion oscillations and blow-off. Hydrogen enrichment is one of the promising methods that can be used to improve the stable operation of the combustor under extremely lean conditions. Hydrogen enrichment also improves the ignitability and the response of the flame to strain and curvature. These benefits suggest a promising role for hydrogen enrichment in the development of low-emission gas turbine combustion technology. However, the response of the hydrogen enriched flames in the context of combustion instability is not fully understood. Thus, the primary motivation of this study is to understand and underpin the mechanisms of heat release modulation with hydrogen addition in the context of combustion oscillations. There are several well known mechanisms that can promote fluctuations in the heat release in lean flames; namely, variations in mixture ratio, sensitivity of the flames to pressure/velocity oscillations, and the formation and shedding of vortices. Any of these mechanisms can cause combustion oscillations to grow in amplitude through positive feedback until a self-sustaining limit-cycle amplitude is reached. However, there is often a clear distinction between the mechanisms driving linear growth of instability and those which cause the heat release oscillations to saturate to limit-cycle conditions. In order to predict and control combustion instabilities effectively the transition from linear growth to non-linear saturation and the mechanisms governing this transition has to be better understood, especially in industrial type non-/partially premixed flames with hydrogen addition. This proposal aims: a) to study and compare mechanisms of heat release oscillations in bluff-body and swirl stabilised turbulent flames, b) to investigate the effect of flame anchoring and that of spatial and temporal mixture variation, which are relevant to limit-cycle oscillation in practical combustors, and c) to assess and understand the role of hydrogen addition in improving the dynamic stability of the combustor, using simultaneous measurements of flow and heat release via advanced laser diagnostic techniques. The expected outcome of this project is to underpin the mechanisms of combustion oscillations in turbulent flames relevant to practical combustors. In particular, the proposed experiments will highlight the role of flame stabilisation, equivalence ratio variation and hydrogen addition on the non-linear flame response, which is of significant importance for improving the fundamental understanding and prediction of the limit-cycle oscillations in practical combustion systems. This research will lead to development of non-linear flame models for acoustic analysis and also aid the development of new control strategies for elimination of combustion oscillations in industrial combustors.
People |
ORCID iD |
Ramanarayanan Balachandran (Principal Investigator) |
Publications
Dowlut A
(2012)
19th International Congress on Sound & Vibration
in Experimental investigation of dynamic response of acoustically forced turbulent premixed CH4/CO2/air flames.
Hussain T
(2012)
19th International Congress on Sound & Vibration. Vilnius, Lithuania
in Investigation in to the effect of hydrogen enrichment on the response of turbulent premixed flames subjected to acoustic excitation
Hussain T
(2021)
Impact of local secondary gas addition on the dynamics of self-excited ethylene flames
in International Journal of Thermofluids
Hussain T
(2019)
Investigating the effect of local addition of hydrogen to acoustically excited ethylene and methane flames
in International Journal of Hydrogen Energy
Hussain T
(2010)
Fifth European Combustion Meeting. Cardiff, Great Britain
in Experimental Investigation of Response of Hydrogen Enriched Methane Flames to Acoustic Oscillations
Hussain T
(2011)
18th International Congress on Sound & Vibration. Rio de Janeiro, Brazil
in Investigation of the effect of fuel stratification on response of turbulent premixed flames to acoustic excitation
Kariuki J
(2015)
Heat release imaging in turbulent premixed methane-air flames close to blow-off
in Proceedings of the Combustion Institute
Kariuki J
(2016)
Heat Release Imaging in Turbulent Premixed Ethylene-Air Flames Near Blow-off
in Flow, Turbulence and Combustion
Mulla I
(2016)
Evolution of flame-kernel in laser-induced spark ignited mixtures: A parametric study
in Combustion and Flame
Mulla I
(2016)
Heat release rate estimation in laminar premixed flames using laser-induced fluorescence of CH2O and H-atom
in Combustion and Flame
Yuan R
(2015)
Reaction zone visualisation in swirling spray n-heptane flames
in Proceedings of the Combustion Institute
Description | Detailed experimental investatigation was carried out to understand, from a fundamental viewpoint, the nonlinear combustion dynamics of turbulent bluff-body/swirl stabilised flames, with equivalence ratio non-uniformities and the effect of hydrogen enrichment. The results showed that hydrogen addition is an effective way of reducing flame response and the amplitude of self-excitation in ethylene flames. On the other hand, the effectiveness of flame reponse reduction in methane flames was dependent on flow and acoustic forcing conditions. |
Exploitation Route | It is envisaged that the high resolution time-space resolved flame and flow data recorded under acousting forcing conditions of turbulent ethylene and methane flames, could be used for validating various industrially relevant computational models. The high resolution time and space resolved flame response data, together with detailed boundary conditions obtained during this project could be used as a validation case of computational and theoretical flame models. |
Sectors | Energy |
Description | The research enabled detailed understanding nonlinear acoustic flame response of hydrocarbon flames with hydrogen addition. As a part of this project, a new experimental approach in determining local heat release rate was developed. It is envisaged at this technique is applicable for many practical fuel flexible combustion systems. |
First Year Of Impact | 2011 |
Sector | Aerospace, Defence and Marine,Energy |
Description | EPSRC responsive mode |
Amount | £757,129 (GBP) |
Funding ID | EP/P003036/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 01/2017 |
End | 12/2019 |
Title | Heat release rate imaging using H atom |
Description | A new measurement method was developed. This method will allow imaging/measuring local heat release - a key parameter for combustion analysis - applicable to future low emission systems. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2014 |
Provided To Others? | Yes |
Impact | It is envisaged that this method will be adopted by combustion community for fundamental and applied research. |
Description | Combustor thermoacoustics for multi-burner low emissions gas turbines (CHAMBER) |
Organisation | Imperial College London |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | At UCL, I will undertaking experimental research that will provide further input into theoretical/modelling efforts of Dr Aimee Morgans at Imperial. |
Collaborator Contribution | Dr Aimee Morgans' open source acoustic analysis tool will be employed to model the experimental work at UCL. The joint effort is likely to underpin nonlinear flame, acoustic interaction in multi-burner combustion systems relevant to gas turbine engines. |
Impact | The work is expected to generate flame transfer (describing) functions relevant to practical combustion devices. |
Start Year | 2017 |
Description | Multi-university partnership on heat release imaging |
Organisation | Indian Institute of Technology Madras |
Country | India |
Sector | Academic/University |
PI Contribution | The measurement method developed in this project, local heat release imaging, was applied to new problems in collaboration with University of Cambridge and Indian Institute of Technology Madras, India (IITM). |
Collaborator Contribution | University of Cambridge team shared simulation data and their expertise on lean extinction was provided (also helped conduct experiments) IITM research spent time at UCL conducting experiments and undergoing training. |
Impact | Three publications - DOIs: 10.1007/s10494-016-9720-y 10.1016/j.combustflame.2015.12.023 10.1016/j.combustflame.2015.11.029 |
Start Year | 2014 |
Description | Multi-university partnership on heat release imaging |
Organisation | University of Cambridge |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | The measurement method developed in this project, local heat release imaging, was applied to new problems in collaboration with University of Cambridge and Indian Institute of Technology Madras, India (IITM). |
Collaborator Contribution | University of Cambridge team shared simulation data and their expertise on lean extinction was provided (also helped conduct experiments) IITM research spent time at UCL conducting experiments and undergoing training. |
Impact | Three publications - DOIs: 10.1007/s10494-016-9720-y 10.1016/j.combustflame.2015.12.023 10.1016/j.combustflame.2015.11.029 |
Start Year | 2014 |