Aerodynamics of lean direct injection combustor with multi-swirler arrays

Multi-point Lean Direct Injection (LDI) combustion focuses on low NOx emissions under extremely high temperature and pressure environment as might be used in high performance aircraft engines in the near future. The performance of the multi-point LDI combustor directly depends on the aerodynamics of the combustor swirlers and their different combinations. Therefore, further understanding of the underlying physical performance of swirler arrays is one of the primary requirements for advanced LDI combustor design. The focus of this dissertation is to investigate the aerodynamics of co-rotating and counter-rotating multi-swirler arrays. This study covers two aspects of investigation, experimental and computational. Experimental measurements were conducted on the flow fields of a macrolaminated radial swirler, a discrete jet swirler with different size confinements, and co-rotating and counter-rotating swirler arrays using the discrete jet swirler. Computational studies of the flow in the swirler and the downstream tube were carried out using k-&egr; and Reynolds stress turbulence models and the results were compared with experimental data.; The experimental measurements show that the swirling flow generated by the macrolaminated swirler is not uniform. Discrete air jets can be found near the exit. The square chamber strongly affects the velocity distribution. The study on the flow structures of a discrete jet swirler in three different size confinements shows that the confinement size strongly affects flow structure such as the recirculation zone size, velocity distribution and turbulence levels. The experimental results of co-rotating and counter-rotating swirler array indicate that the considered flow fields have very complicated structures. The existence of recirculation zones and strong turbulence levels indicate the potential for good combustion performance and Low NOx emissions.; For the single swirler case, both the k-&egr; and the Reynolds stress models were able to predict the flow structure very well. However for the co-rotating swirler array, the Reynolds stress model proved superior to the k-&egr; model, and was able to predict the extremely complicated flow structure well.