Optical diagnostics of atomization and combustion of kerosene in a model combustion chamber for a gas turbine engine

Abstract

Optical diagnostic techniques have been employed at a combustion chamber test rig for investigation of the liquid fuel atomization and mixing with air, and of combustion of the fuel-air mixture formed in the flow. Certain characteristics of the kerosene spray and of the kerosene-air mixture combustion have been determined. An axisymmetric single-burner section with a pneumatic atomizer in the flame tube head was investigated at excess air ratios α = 0.9-1.5. The transverse spatial distributions of average kerosene droplet dimensions and the axial component of the average volume flux of the fuel have been measured in the axial cross-section of the mixture flow by using the Particle Shadow Velocimetry (PSV) technique. The results prove the efficiency of the investigated atomizer in the formation of finely dispersed kerosene- air flow with a regular structure which enables the stability of the combustion process. By employing Coherent Anti-Stokes Raman Scattering (CARS) during combustion of the produced kerosene-air mixture the statistical characteristics of instantaneous local gas temperature fluctuations in the flame and transverse distributions of average temperatures in the flame axial cross-section have been measured. The results demonstrate reasonable temporal stability of the obtained kerosene-air mixture combustion over the measurement period, and the possibility to describe the transverse flow structure and its modifications with the flow composition. The set of the complementary data provided by the PSV and CARS techniques at different excess air ratios characterizes the operation of the combustion chamber and expands the variety of possible flame tube head tests.