Influence of the Primary Spray Characteristics on the Performance of a Double-swirl Airblasting Atomizer

摘要

The pre-filming airblasting atomization system, which is widely employed in the modern aero engine combustors, mainly consists of two parts, i.e., a fuel nozzle and a single or multi-stage swirler. Under various operating conditions of an engine, the primary spray characteristics have different effects on atomization performance. The present investigation has examined the influence of primary spray characteristics on the atomization performance of an airblasting atomizing device composed of a double-stage axial swirler and a dual-orifice pressure atomizer. For a same air-to-fuel ratio (AFR), the fuel has been injected by the main stage alone, or by the pilot stage alternatively. Different fuel pressure drops, accordingly, resulted in different fuel spray quality. Sauter Mean Diameter (SMD) and its related distribution index (N) have been used to assess the overall performance of the atomization quantitatively. Under the same aerodynamic conditions for the swirler, the experimental results showed that the primary spray had significant effects on the overall atomization performance, especially under low power conditions of the engine. In order to attain optimized overall atomization performance, pressure drop of the fuel and aerodynamic parameters of the swirler should be matched carefully, which is of great importance to reliable ignition and combustion efficiency of the combustor design.