Fuel distribution and evaporation characteristics downstream of an integrated flameholder

Abstract

The vapor- and liquid-phase fuel distributions play critical roles in the combustion processes of augmented/ramjet combustors. In this study, the fuel distribution and evaporation characteristics downstream of an integrated flameholder in a fan-shaped test section are investigated under different inflow and fuel conditions using physical and optical methods. The experimental results denote that the Sauter mean diameter (SMD) and liquid equivalence ratio Φliquid at the cross-sections decrease with the increasing inflow temperature T1, inflow velocity V1, fuel temperature Tf or flow distance, while increase with an increasing global equivalence ratio ϕ. The total equivalence ratio Φtotal is conserved at all cross-sections; thus, the evaporation rate η at the measurement points increase with increasing inlet conditions and flow distance, similar to the vapor-phase equivalence ratio Φvapor. Under a given condition, along the radial direction from the outer wall to the central axis of the fan-shaped test section, the Φvapor and η initially increase, then decrease, and finally increase again, and reaching their maximum at a radius of 10/11, whereas Φliquid always increase; note that these trends are not affected by the inlet conditions. In any given cross-section, the SMD and Φvapor variations are significant for increasing V1 or Tf, whereas they are relatively small for increasing T1 or ϕ. This indicates that increasing the V1 or Tf is more conducive for promoting fuel atomization and evaporation than increasing the T1 or ϕ.