An experiment demonstrating the RFA-2000's unique ability to measure the time varying fuel-air mixing properties of a methane-air fueled lean premixed gas turbine combustor is shown schematically above. For this example, the inlet pressures at the sample probe were very high - permitting a faster than 500 Hz time resolution. In fact, the data shown below was acquired at 12 kHz (with a system time resolution of about 2 kHz). The sample inlet pressure was about 10 atm and the sample inlet stinger was placed in the post fuel injection mixing zone to provide detailed time histories of the fuel-air fluctuations with it's corresponding sprectral density graph. The measurements from the RFA-2000 show a direct correlation with the dynamic pressure measurements. This indicates that the fuel-air mixing process is directly correlated with the pressure fluctuations in a gas turbine injector. The data can also be processed to show the histogram or probability density function (PDF) of the equivalence ratio. The PDF shows how much 'time' an injector spends at a given equivalence ratio. The PDF reveals instantly, whether a particular injector will be clean burning. Experimental data provided courtesy, Prof. R. W. Dibble and J. Girard, U.C. Berkeley (2000).
