Abstract

To stabilize unstable combustion systems in gas turbines, aero-engines, rocket motors, boilers and furnaces, there is a need to develop a simple but applicable mitigation/control strategy. The present work considers using an electrical heater to mitigate limit cycle thermoacoustic oscillations sustained by a premixed flame. For this, nonlinear recurrence relation analysis of the thermoacoustic system with the premixed flame and an electrical heater confined is conducted first. It is shown that the heater placed at a proper location results in significant damping on the thermoacoustic oscillations. Experimental measurements are then performed. It shows that the heater can dampen thermoacoustic oscillations, depending strongly on (1) its location and (2) its output electrical power. The minimum electrical power Qmins is determined and compared for four different axial locations. The optimum position xopts at which the heater is most effective in damping combustion-excited limit cycle oscillations is shown to be at 0.72⩽xs/L⩽0.75 for the eigenmode with frequency ω1/2π≈240Hz. This finding agrees well with those from the energy exchange analyses via linearized flame and heater models. It is also experimentally shown that sound pressure level is reduced by 70dB, as the heater is placed at xopts and its output power is increased to 218.2W. Furthermore, the thermoacoustic mode frequencies are found to be increased with the limit cycle oscillating being dampened. The successful experimental demonstration opens up another possible way to mitigate/control thermoacoustic oscillations using an electrical heater.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.