TIME-RESOLVED TEMPERATURE-MEASUREMENTS IN THE DEVELOPING REGION OF ANELLIPTIC, JET-DIFFUSION FLAME AT A REYNOLDS-NUMBER OF 6000

Time resolved temperature measurements were performed in the developin g region of an elliptic, jet-diffusion dame using fine-wire thermocoup les compensated for thermal inertia effects. Measurements of mean and rms temperature profiles, as well as power spectral densities and prob ability density functions of temperature were obtained along the cente rline and radially along the major and minor axes for nondimensional a xial stations in the range of 5 less than or equal to z/D-h less than or equal to 30. Significant differences in the thermal structure of th is elliptical jet flame along the minor and major axes were observed. Higher temperature fluctuations along the minor axis in the fuel-side mixing layer and higher temperature fluctuations along the major axis iri the air-side mixing layer were observed. Stronger, buoyancy-driven flow structures in the air-side shear layer caused more radial moveme nt of the reaction zone along the major axis as evidenced by rms tempe rature profiles with substantially higher values (200 K) farther out r adially for all the axial stations where measurements were made. This greater radial movement of the reaction zone was sufficiently strong t o cause a faster destruction of the inner, small-scale structures alon g the fuel side of the major axis such that less mixing of hot and col d fluid pockets (lower rms temperatures) was observed.