Vortex-Stabilized Flames and Heat Release

Vortex shedding plays a significant role in maintaining self-sustained combustion instabilities in dump combustors. Vortices may entrain a large amount of hot recirculating products into fresh reactants, causing a substantial modification in 

Interestingly, the high cycle of heat release or simply the hot spot in this case closely follows the vortex development. The main difference from the previous case was that the inlet velocity was much lower, while the equivalence ratio was higher. In other words, the convective time scale wtis less and the chemical time scale was higher. This suggests that one of the important parameters to consider in identifying the proper location of controlled fuel injection is the Damkohler number. Near the flame blow-off limit, however, one would expect the hot spot to lag the vortices slightly. 

3 DUMP COMBUSTOR CHARACTERIZATION AND LIQUID-FUELED ACTIVE CONTROL 

The experiments were performed in a 102-millimeter diameter axisymmetric dump combustor shown in Fig. 16.1a. The inlet diameter is 41 mm. Ethylene was injected at 24.5 inlet diameters upstream of the dump plane to simulate the prevaporized, premixed reactants entering a ramjet combustor. The cylindrical combustor is 610 mm long and is capped by a 38-millimeter diameter exhaust 

Natural operation characteristics of the uncontrolled dump combustor are shown in Fig. 16.9. 

---