一种新型燃气轮机燃烧室双相喷射器的喷雾特性和速度分布特性研究

A novel airblast injector is designed for gas turbine combustors. Unlike standard pressure swirl and prefilming/non-prefilming air blast atomizers, the novel injector is designed to improve the fuel injection delivery to the injector by applying porous stainless steel tube with 7 m porosity to enhance atomization of the fuel. The porous tube is used to inject the fuel between two air streams, viz. through inner section of the tube and the other swirling stream merging downstream of the tube. Jet-A fuel is injected through the outer surface of the porous tube. The swirler located at the bottom of the porous tube, swirl vane angle and air split are selected to increase the amount of air through the tube and facilitate the atomization. Due to the permeability of the tube, a thin liquid sheet is produced along the inner surface of the tube. The liquid sheet is atomized by the inner airstream by surface stripping. The advantage of such an injector is that the surface area of contact between the fuel and air can be increased, which can enhance the distribution of the fuel more effectively, obtain constant uniform liquid sheets under all liquid loadings, and produce a fine spray at engine idle conditions. The injector can also be used to inject simultaneously both liquid and gaseous fuels. An experimental approach is adopted in the present study to characterize initially the spray and fuel placement emanating from this injector. Patternator tests are carried out to study the fuel distribution. The results show a hollow cone spray with symmetric distribution of droplets surface area density. Spray characterization is further analyzed by PDPA measurements. The measured SMD shows that the atomization is reasonably good with wide fuel placement downstream of the atomizer at atmospheric conditions. The effect of pressure drop on the velocity profile is investigated by PIV measurements.