Solid fuel ramjet combustor design

Combustion aspects of solid fuel ramjet (SFRJ) are reviewed. On the point of view of the ability of an SFRJ to operate satisfactorily at all off-design conditions the areas of concern to propulsion system designer are (1) selection of a fuel type, (2) flame holding requirements that limit maximum fuel loading, (3) understanding the fuel regression rate behaviour as a function of flight speed and altitude, (4) diffusion-controlled combustion process and its efficiency enhancement, and (5) inlet/combustor matching. Considering these areas, the following aspects are reviewed from the information available in open literature: (1) different experimental set-up conditions adopted in combustor research, (2) various suitable fuel types, (3) flammability limits, (4) fuel regression rate behaviour, (5) methods of achieving high efficiency in metallized fuel, and (6) various modelling efforts. Detailed discussion is presented on two different types of regression rate mechanism in SFRJ: one that is controlled by the heat transfer processes downstream of the reattachment region and the other by that in the region itself. With a view to demonstrate the use of the information collected through this review, a preliminary design procedure is presented for an SFRJ-assisted gun launched projectile of pseudo-vacuum trajectory. © 1998. Published by Elsevier Science Ltd.