Turbulent velocity and temperature measurements from a gas-fueled technology combustor with a practical fuel injector

Abstract

Combustion characteristics of a propane-fueled, practical injector operating in a burner that closely reproduces the flow patterns of a gas turbine combustor have been investigated. The practical injector converges co-swirling airsheets on either side of a coannular fuel sheet into the central air passage. Instantaneous planar-laser-induced fluorescence (PLIF) images of OH radical, laser doppler anemometer (LDA) measurements of mean and rms velocity, and coherent anti-Stokes Raman spectroscopic (CARS) measurements of mean and rms temperatures in the same burner at the same operating conditions have provided improved understanding of the complicated processes in a gas turbine combustor. The PLIF images of the OH radical have confirmed the vortex characteristics of the swirling flames and the highly variable nature of the flame shape as φ and air flow rate was changed. Correlation of these images with air flow through the various nozzle passageways confirms that the local φ must lie between the lean and rich flammability limits for a flame to be locally present. Three recirculation zones were identified from LDA measurements. The highest axial velocity region is about 75 mm downstream for the fuel lean case, but is near the injector for the fuel rich case. The highest tangential velocities are located near the injector for both lean and rich cases. The effects of the injector on velocity were dissipated by one combustor diameter downstream. Large rms velocities occurred in areas where significant velocity gradients exist. The high temperatures changed location as the fuel equivalence ratio was varied from fuel lean (over the injector) to fuel rich (near the outer recirculation zone). The high-temperature regions are consistent with the PLIF images of OH radical, and become relative uniform by about one combustor diameter downstream. Measured temperatures never exceeded the peak theoretical adiabatic flame temperature.