Dropwise ignition versus external ignition for multicomponent fuel sprays
Abstract
An attempt has been made to identify conditions for dropwise ignition and spray ignition. Both pure as well as multicomponent fuels are considered. For dropwise ignition, an existing ignition criterion has been modified to account for the nonlinear dependence of reaction rate on fuel and oxygen concentrations and to account for the multicomponent nature of the fuel. The external or spray ignition is considered through the zero heat flux condition at the ignition source. The effect of chemical kinetics is examined by employing reaction schemes with unity as well as non-unity exponents of fuel and oxygen concentrations. Results indicate that for most of the conditions considered, the individual droplet ignition is favored over the external ignition. Only when the drop diameter is smaller than 30 microns, the spray ignites earlier than droplets. The addition of a small amount of a volatile component significantly enhances the ignitability of both modes. However, the effect is stronger for the dropwise ignition mode.
- Publication:
-
AIAA, ASME, SAE, and ASEE, 24th Joint Propulsion Conference
- Pub Date:
- July 1988
- Bibcode:
- 1988jpbm.confQ....M
- Keywords:
-
- Combustion Chemistry;
- Detonable Gas Mixtures;
- Drop Size;
- Fuel Sprays;
- Ignition;
- Combustion Physics;
- Two Phase Flow;
- Fluid Mechanics and Heat Transfer