Experimental Combustion Dynamics Behavior Of A Multi-Element Lean Direct Injection (LDI) Gas Turbine Combustor

Abstract

An experimental investigation of the combustion dynamic characteristics of a research multi-element lean direct injection (LDI) combustor under simulated gas turbine conditions was conducted. The objective was to gain a better understanding of the physical phenomena inside a pressurized flametube combustion chamber under acoustically isolated conditions. A nine-point swirl venturi lean direct injection (SV-LDI) geometry was evaluated at inlet pressures up to 2,413 kPa and non-vitiated air temperatures up to 867 K. The equivalence ratio was varied to obtain adiabatic flame temperatures between 1388 K and 1905 K. Dynamic pressure measurements were taken upstream of the SV-LDI, in the combustion zone and downstream of the exit nozzle. The measurements showed that combustion dynamics were fairly small when the fuel was distributed uniformly and mostly due to fluid dynamics effects. Dynamic pressure fluctuations larger than 40 kPa at low frequencies were measured at 653 K inlet temperature and 1117 kPa inlet pressure when fuel was shifted and the pilot fuel injector equivalence ratio was increased to 0.72.

Comparison of Combustion Dynamic Characteristics of Two Advanced Multi-Cup Fuel Injectors

“…The figures also show that in general, the amplitude of the dynamic pressure fluctuations, increase as the equivalence ratio increases. This same behavior was reported in [15] for a research multi-point fuel injector. They identified some of the same factors that contribute to instability growth, like the phase relationship between the heat addition and the combustion chamber acoustics (Rayleigh criterion), vortex shedding, other turbulent phenomena generated by the fuel injectors, and the energy introduced into the combustor by burning Utilizing the combustion instability criteria listed above, the 3ZI-1 injector exhibited unstable behavior at the following conditions: inlet pressure 710 kPa, inlet temperature 570 K and ϕ=0.546 and 0.677; inlet pressure 1,034 kPa, inlet temperature 570 K, and ϕ=0.421 and 0.536; and at an inlet pressure of 1,034 kPa, inlet temperature 570 K, and ϕ=0.536.…”

“…Others utilized multiple injectors more closely resembling an actual engine configuration and were experimentally evaluated at inlet conditions close to actual engine conditions. [14][15][16].…”