Experimental Augmentation of Turbulent Flames Through Free Radicals Delivered In Situ

Abstract

Abstract Experiments are conducted with the aim of augmenting turbulent flames with specific applications to high-speed combustion (for example, Scramjets). Augmentation includes extension of rich and lean limits, extension of aerodynamic limits, and augmentations in efficiency (also, signature minimization). While the concept of free radicals use for these purposes is NOT new, the method of delivery is. Free radicals are very short lived and highly reactive; they are needed in small concentrations at specific sites at requisite times. We use stable compounds that are known to decompose at specific temperatures; their decomposition products are rich in specific free radicals that are delivered in situ. The method thus obviates the problems of storage, delivery, and loss. A methane/enriched-air turbulent flame system is used. The apparatus and flame studies have been extensively reported in the open literature. Dilute hydrogen peroxide is used as the free radicals source. The flame blow-off limit is determined, for example, in the lean limit. The same configuration is used, now with the H202 injection upstream. Extensions of the lean limit from 1 to 50 percent are seen.The results are found to be consistent with a simple turbulence theory.