Schematic Design And Parametric Optimization Of The Air-blast Atomizing Duel-fuel Atomizer

Currently, most advanced engineering applied gas turbines have the capacity to to usedual fuel in order to cope with such problems as energy deficiency and environment pollution.The dual fuel nozzle is one of the important components affecting device performance. Astheories on performance prediction and structural design of dual fuel nozzle are incomplete, itis significant to make studies on atomization prediction model and nozzle structure of dualfuel air atomization nozzle.By using FLUENT software, this thesis first makes systematic researches of pneumaticnebulization performance of liquid membrane in middle structure of double air ring cavity,and analyzes the impact of flow and structural parameters on atomization effect; besides，itgives a new SMD prediction model and accuracy criterion and explains unstable liquidmembrane wave breaking theory from a physical point of view. Based on theoretical analysis,it designs three kinds of dual fuel nozzle of different cyclone forms, confirms the best solutionby making contrastive analysis of structure property of combustion flowfield under designconditions with cracking gas as fuel, and optimizes nozzle distance and area ratio of inner andouter rings on this cyclone plan. Lastly, it makes systematic analysis of off-designperformance of nozzle with optimized structure, including such conditions as steamreinjection ability, diesel cracking gas and co-combustion, and single combustion of crackinggas.Researches results have shown that differences between gas and liquid are main reasonsfor unstable liquid membrane during the initial process of pneumatic nebulization. The dualfuel pneumatic nebulization nozzle in the form of outer ring cyclone will have the best effectin combustion flowfield under design conditions and will have the best nozzle distance andratio of inner and outer rings. The optimized nozzle will have good performance in a largeflow range while burning independently cracking gas. The oil and gas mixed combustion fieldhave shown that with the increase of fuel, the temperature of combustion zone rises and theflame moves backwards, but in general, the nozzle is able to meet requirements of dual fuelmixed combustion. The steam reinjection ability of this nozzle is restricted by the area ofinner flux area, however, the combustion chamber flameout resulted by the obstructionbetween the fuel oil and oxidant when steam is reinjected from outer ring can be resolved by the simple structure to reinject steam from center gas circuit.