Abstract
The Stagnation Point Reverse Flow (SPRF) combustor has been shown to operate stably while producing ultra-low NOx emissions over a range of loadings and equivalence ratios in both gas and liquid fueled operation. In nonpremixed gaseous operation, low NOx levels have been attributed to initial shielding of fuel from hot products allowing internal premixing of fuel and air to nearly the global equivalence ratio before burning. Various optical diagnostic techniques, such as chemiluminescence imaging and laser scattering, are employed to elucidate the combustion processes of this novel combustor in liquid-fueled operation. While the overall flow features are similar for both gas and liquid fuels, the combustion characteristics and NOx performance are strongly controlled by fuel dispersion and evaporation in liquid operation. Here, fuel dispersion is controlled by varying the placement of the fuel injector, which is centrally located within the annular air inlet tube. When the liquid injector is located in plane with the exit of the air annulus, the fuel remains initially shielded from the high temperature return products (similar to the gaseous case) producing a highly lifted flame. On the other hand, injecting the liquid upstream produces a more well-dispersed fuel pattern at the reactant inlet. This leads to a reduction of the equivalence ratio in the fuel consuming reaction zones. Hence the NOx emissions were found to be lower for this less shielded injector configuration over the range of global equivalence ratios and loadings investigated. Thus it is conjectured that the added delay caused by fuel evaporation before mixing and combustion can occur, changes the optimal shielding required for liquid-fueled operation.
Paper version not known (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call