Experimental study of compact ram combustor with double-staged flameholders for ATR engine

Abstract

As the next generation propulsion system, an Air Turbo Ram (ATR) engine, a combined engine of ramjet and turbojet, is one of the most promising candidates. This engine needs to be compact to accommodate heavier payloads and to enable longer distance flight. The ram combustor, its major component, is no exception and required to be more compact and shorter in its axial length. But the defect of shortening it is the combustion efficiency becomes lower. To shorten the ram combustor and to obtain an excellent combustion efficiency, the doublestaged flameholder scheme was introduced. A rear flameholder, installed downstream of a conventional one, aims to quickly expand flames to the surrounding. The flame expansion was experimentally observed by a ram combustion test in a 120° sector passage. It came with a drastic combustion efficiency rise, no thermal damage to the rear flameholder. The ram combustor with doublestaged flameholders, which was approximately 40 % shorter in the axial direction than that with a conventional single-staged flameholder, was found to satisfy its technical goals. Nomenclature