Industrial gas turbines are primarily fueled with natural gas. However, changes in fuel cost and availability, and a desire to control carbon dioxide emissions, are creating pressure to utilize other fuels. There is an increased interest in the use of fuels from coal gasification, such as syngas and hydrogen, and renewable fuels, such as biogas and biodiesel. Current turbine fuel injectors have had years of development to optimize their performance with natural gas. The new fuels appearing on the horizon can have combustion properties that differ substantially from natural gas. Factors such as turbulent flame speed, heat content, autoignition characteristics, and range of flammability must be considered when evaluating injector performance. The low swirl injector utilizes a unique flame stabilization mechanism and is under development for gas turbine applications. Its design and mode of operation allow it to operate effectively over a wide range of conditions. Studies conducted at LBNL indicate that the LSI can operate on fuels with a wide range of flame speeds, including hydrogen. It can also utilize low heat content fuels, such as biogas and syngas. We will discuss the low swirl injector operating parameters, and how the LSC performs with various alternative fuels.

Transmission electron microscopy was used to study defects in lateral epitaxial layers of GaN which were overgrown on a template of a-plane (11{und 2}0) GaN grown on (1{und 1}02) r-plane Al2O3. A high density of basal stacking faults is formed in these layers because the c-planes of wurtzite structure are arranged along the growth direction. Density of these faults is decreasing at least by two orders of magnitude lower in the wings compared to the seed areas. Prismatic stacking faults and threading dislocations are also observed, but their densities drastically decrease in the wings. The wings grow with opposite polarities and the Ga-wing width is at least 6 times larger than N-wing and coalescence is rather difficult. Some tilt and twist was detected using Large Angle Convergent Beam Electron Diffraction.