ABSTRACT
With the increasing concern for environmental protection, low pollutant emissions are an important component in modern gas turbines[1]. An LDI combustor is a design concept for low pollutant emissions. In the LDI system, the fuel is injected directly into the flame without being premixed or prevaporized and is burnt under fuel-lean conditions for making the lowest possible flame temperature. Therefore, it is important to achieve a fine atomization and mixing of the fuel and air quickly and uniformly. An LDI is a concept that depends heavily on the swirler designs. Researchers at the NASA Glenn Research Center did lots of work on the LDI combustor by experimental and numerical methods[1-3]. Yongqiang Fu et al. (2005) did experimental research on the nonreacting flowof anLDI combustor in detail; Farhad et al. (2006) used a RANS method to simulate the flow field of an LDI combustor; H. El-Asrag et al. (2007) studied the LDI combustor by LES methods with a Dynamic S-L model. These results show that the LESs give a better performance than RANS. However, all these result do not match the experimental data well enough, especially the flow structure which cannot represent in intense turbulent regions downstream, the exit of the convergent-divergent venture. Therefore, further work needs to be done.
