Acoustic Reynolds Stress: The Source of Coherent Structures During Combustion Instability - Novel Combustion Concepts for Sustainable Energy Development - page 368

Fig. 6 Variation of average fl flame length with increase in Reynolds number

Fig. 7 Comparison of turbulent kinetic energy spectra at x/h = 4 for Re = 18,000 and 33,000

shows the turbulent kinetic energy (TKE) spectra for these cases. It is clearly seen
that TKE is higher in large scales for Re = 33,000 when compared to 18000. Also,
there is a sharp decrease in TKE in small scales for Re = 33,000 relative to 18,000.
This reveals that the large scales are being formed at the expense of small scales at
Re = 33,000, bringing out evidence for the ARS to churn these large-scale struc-
tures. The ARS reorganises the field into large-scale coherent structures and

prevents their decay into small scales, as observed in experiments.

fl ow