An Investigation On The Performance Of Aerodynamic Multi-point Fuel Injector

Aerodynamic multi-point fuel injector (AMPI)could be applied in low emission combustor ofcivil aeroengine by forming the uniform fuel-air mixture to effectively reduce the emissions. Thebasic principle is to put fuel-air mixture into the combustion area from distributed jet orifice by usingpartially lean premixed and prevaporized concept. The concept design of the aerodynamic multi-pointfuel injector has been completed. The numerical simulation and experimental research for thecharacteristics of evaporation rate and mixing efficiency under different jet orifice configuration arealso carried out. These main results are as follows:In this paper, the design of fuel-air mixing and flow strategy had been completed. In theconception of fuel partially lean premixed and prevaporized, the reasonable range of fuel/air ratio andevaporation rate had also been analyzed. Determined size of vaporization refers to the length of evensegment, the slot width and vertex of the afterbody of AMPI, the distance between nozzles, and thedirection of jet.The preliminary research on inlet flow velocity, inlet air temperature, jet orifice scheme, effectsof the fuel delivery on the performance of fuel spray, evaporation and mixing performance had beencompleted. The result of study shows when the inlet flow velocity exceeds0.1Ma, the jet orificeconfiguration can have a visible second spray affect on fuel. The temperature is the most significantelement affecting evaporation rate, and the higher the temperature of the inlet, the more visible affectof vaporize. In the inlet temperature of373K, a fat lot evaporation occurs, and when the inlettemperature gets673K, evaporation rate could be over65%. Under the same inlet temperature andfuel flux，the smaller area and aperture of the orifice can stay much more time of the fuel and higherevaporation rate. The jet orifice scheme and evaporation rate are the most significant elementsaffecting the fuel-air mixing. The larger aperture of the jet orifice can make the higher penetration offuel. Under the same aperture and different pitch of the orifice，penetration of fuel basically remainthe same. Under the atmospheric temperature, the same aperture D or the pitch of holes S，can match abetter aperture D or the pitch of holes S, which can make the better fuel-air mixture distributiondownstream of the vaporization; Under the same orifice area, the reasonable choice is to make S/Drange from2to2.5. When the evaporation rate is under35%, the evaporation rate is the mostsignificant element affecting the distribution of fuel-air mixture. The higher evaporation rate，thebetter uniform distribution of the fuel-air mixture. When the evaporation rate is over65%, the jet orifice configuration shows the distinct affect on the distribution of the fuel-air mixture. This moment,under the same hole area, S/D ranging from2.5to3can make a better fuel-air distribution. Whenaerodynamic multi-point fuel injector can’t afford the fuel flux, it would come out the fuel spilling. Inthe experiment of this paper, when the fuel spilling in the facility come out, the critical equivalenceratio in the vaporization can be over3.