Vortex interactions with flames play a key role in many practical combustion applications. Such interactions drive a large class of combustion instabilities, they control to a great extent the structure of turbulent flames and the corresponding rates of reaction, they occur under transient operations or when flames travel in ducts containing obstacles. Vortices of various types are often used to enhance mixing, organize the flame region, and improve the flame stabilization process. The analysis of flame/vortex interactions has value in the development of our understanding of basic mechanisms in turbulent combustion and combustion instability. The problem has been extensively investigated in recent years. Progress accomplished in theoretical, numerical and experimental investigations on flame/vortex interactions is reviewed in this article.
Systematic measurements of OH chemiluminescence from a premixed laminar flame at pressures and equivalence ratios of 0.5-2.5 MPa and 0.66-0.86, respectively, were studied. The functional relationship was monotonically decreasing for decreasing equivalence ratio and increasing pressure. For a given system, one can deduce the equivalence ratio if the airflow rate and pressure are known. Through a band-pass filter with a photo-multiplier tube, the signal from the first electronically excited state of OH to ground at 305.4 nm was detected. OH emission decreased considerably with increasing pressure for constant mass flow rate. A linear relationship was noted between increasing mass flow and increasing chemiluminescence. Thus, a suitable resolution and dynamic range existed to sufficiently control high-pressure flame to minimize both NO and CO emissions. Results were presented for a simple, active-control system using OH chemiluminescence measurements to show flame stabilization for equivalence ratio disturbances at fixed, elevated pressures. Only qualitative agreement was noted between the measurements and numerical predictions of OH chemiluminescence utilizing an adiabatic, freely propagating premixed flame.
