スクラムジェットエンジンの混合・燃焼形態に関する考察 弱燃焼から強燃焼への遷移過程

Abstract

The main purpose of this study is to reveal a transition mechanism between two typical combustion modes called ‘weak-combustion’ and ‘intensive-combustion’ observed in the firing tests of scramjet engines at Mach 4, 6 and 8 conditions of Ramjet Engine Test Facility (RJTF). For this purpose, flow structures in the combustor and their changes during the transition of the combustion mode are investigated by cold flow tests as well as numerical simulations. These results and the firing test results led us to conclude 1) that transition from ‘weak mode’ to ‘intensive mode’ is the consequence of the mutual interaction between enhancement of fuel/air mixing as well as combustion within the boundary layer and the growth of the boundary layer separation area and 2) that in the present engine principal fuel/air mixing and combustion strongly depend on the occurrence of large-scale boundary layer separation, thus the resulting principal combustion is characterized to be subsonic combustion within the separated boundary layer.