微型燃气轮机喷嘴射流和雾化特性研究

为在微型燃气轮机内营造低氧贫燃氛围以实现液体燃料的节能减排,利用可适性多普勒激光测速仪APV/LDV对改造喷嘴附近截面进行了测量和分析,用以考查近喷嘴处的气液混合夹带情况以及雾滴尺寸及分布。结果发现：增加外部涡旋气流后,喷孔附近雾滴的动量增大,雾锥内出现一小回流区,对应湍流度较大区域附近;燃烧时较大切向动量及湍流度利于空气与周围高温烟气迅速混合形成低氧环境,并和雾滴掺混进行热量和动量的传递;喷孔出口雾化角增大,使得雾滴更加分散,利于雾化、气液混合和传热传质;所有实验工况雾滴平均直径低于50μm,且为偏高斯分布。该研究为液体燃料喷嘴的设计提供了参考,可作为微型燃气轮机燃烧室热态反应物流场的参考依据。

Spray and atomization performance of a micro gas turbine nozzle

To create a low 02 concentration and lean combustion atmosphere in a micro gas turbine to achieve the aim of energy saving and low emission, the isothermal spray flow near the reconstructed nozzle and its atomization performance were investigated using the Adaptive Doppler Laser Velocimetry （APV/LDV）. Then the mixing and entrainment of the gas/liquid near the nozzle and the droplet size and their distribution were analyzed. The results show that the external vortex air flow increases the momentum of the droplets near the nozzle and causes a small recirculation flow which appeares around the region with a strong turbulence in the spray. The large tangential momentum and turbulent intensity are helpful to the rapid mixing of air and the surrounding flue gases which would cause a low 02 concentration and the mixing of the mixed gas with droplets to transfer heat and momentum. The average droplets diameter of all operating modes is no more than 50tam and the droplets match the biased Gauss distribution. The vortex air flow increases the outlet spray angle and makes droplets more dispersed, which is propitious to the atomization, gas-liquid mixing and heat and mass transfer. The study provides reference for the design of liquid atomizer and is a basis for thermal flow study in a micro gas turbine.