Saumya SHEKHAR, Bhushan THOMBARE, Vinayak MALHOTRA

Effect of acoustic energy on onset of fire propagation phenomenon

Scholars and scientists have been making efforts to discover ways to control and lessen the resonance of concurrent fires such as forest fires, and various space fires; however, no potential solutions have been concluded from their studies so far. The origin of these types of fires concerns the unstable nature of the flames and the considerable unpredictability associated with them. This work led us to do proper experimentation for the effect of sound on the spreading of the flames. Sound energy as a wave is always accompanied by compression and rarefaction. As an external effect, sound in the immediate vicinity of spreading flame can affect the flame spread rates. Appreciable work had been carried out however; the effect of sound on flames in a purely natural convective environment is an aspect yet to be thoroughly understood. Flame spread rate is a direct indication of forwarding heat transfer from burning to non-burning region. Formation of localized pressure and velocity fields occurs around the pilot fuel by the presence of sound waves. Change in heat transfer may results in increment or decrement in spread rates, when compared with one without sound. The present work attempts physical insight into the effect of sound frequency of intermediate range (3500 Hz to 7500Hz) on the spreading of flames in different configurations coupled with external sources. Results advocate the noteworthy impact of acoustics on the fire propagation phenomenon in distinct modes. Experimentation have revealed that acoustics has a critical influence on fire propagation, reducing the spread rate by 100 percent in a unilateral configuration.

Keywords:

Acoustics Energy Interaction Compression, Fire Propagation, Rarefaction,

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[1] Chiu HH, Summerfield, M, Theory of combustion noise, Aerospace and Mechanical sciences report. Princeton University, New Jersey; USA, 1973.
[2] Schadow, KC, Gutmark, E. Combustion instability related to vortex shedding in dump combustors and their passive control. Progress in Energy and Combustion Science 1992; 18(2): 117-132.
[3] Lovett JA, Turns SR. Experiments on axis symmetrically pulsed turbulent jet flames. AIAA Journal1990; 28:38–46.
[4] Saito, M, Sato, M, Nishimura, A. Soot suppression by acoustic oscillated combustion. Fuel 1998; 77:973–978.
[5] Hertzberg JR. Conditions for a split diffusion flame. Combust Flame 1997; 107:314–322.
[6] Suzuki M, Atarashi T, Masuda W. Behavior and structure of internal fuel-jet in diffusion flame under transverse acoustic excitation. Combust Sci Tech 2007; 179:2581–2597.
[7] Kozlov VV, Grek GR, Katasonov MM, Korobeinichev OP, Litvinenko YA, Shmakov AG. Stability of subsonic microjet flows and combustion. J Flow Contr Meas Vis 2013; 1:108–111.
[8] Nair, V, Sujith, RI. Multifractality in combustion noise: predicting an impending combustion instability. J. Fluid Mech2014; 747: 635-655.
[9] Mondal, S, Unni, VR, Sujith, RI. Onset of thermoacoustic instability in turbulent combustors: an emergence of synchronized periodicity through formation of chimera-like states. J. Fluid Mech. 2017;811: 659-681.
[10] Tiwari, P, Ramanan, V, Malhotra, V. An Experimental Insight into Thermoacoustic Smoldering. Journal of Space Exploration 2017;6(1): 119.
[11] X. Huang. Critical drip size and blue flame shedding of dripping ignition in fire. Sci. Rep.2018; 8: 1–13
[12] Magina, N, Acharya, V, Lieuwen, T. Forced response of laminar non-premixed jet flames. Prog. Energy Combust. Sci.2019; 70:89–118.
[13] George, NB, Unni, VR, Raghunathan, M, Sujith, RI. Pattern formation during transition from combustion noise to thermoacoustic instability via intermittency. Journal of Fluid Mechanics 2018; 849: 615–644.
[14] Sujith, RI, Unni, VR. Complex system approach to investigate and mitigate thermoacoustic instability in turbulent combustors. Physics of Fluids2020;32(6): 061401.
[15] Tatnell, DM, Heath, MS, Hepplestone, SP, Hibbins, AP, Hornett, SM, Horsley, SAR, Horsell, DW. Coupling and confinement of current in thermoacoustic phased arrays. Science Advances, Applied Physics 2020;6(27): eabb2752.
[16] Vinayak Malhotra et al 2021 IOP Conf. Ser.: Mater. Sci. Eng. 1168, 012019