Temperatures of Spark Kernels Discharging into Quiescent or Crossflow Conditions

This work determines how the temperature of spark kernels changes for quiescent and crossflow conditions. Previous efforts have primarily considered kernels in quiescent conditions and typically neglected how the temperature changes with time. The latter is significant because the temperature evolution is critical for determining if reactions become self-sustaining. Kernels were generated using a gas turbine engine igniter. Temperatures were determined from radiation intensity measurements (FLIR SC6700) and by solving the radiation transfer equation. Kernels were discharged into a wind tunnel with crossflow velocities between 0 and 15.6m/s. Kernels developed into toroidal vortices for all conditions. The average peak temperature in quiescent conditions was near 950K and nearly 1250K at the highest crossflow velocity. Higher temperatures were observed at the upstream side of kernels when ejecting into a crossflow. The changes in temperatures observed with crossflow are explained by fluid mechanic literature; vortex crossflow interaction alters entrainment into kernels. The sensible energy of kernels, determined from the temperatures, decreased roughly linearly with time for all flow conditions. The highest crossflow velocity had the lowest sensible energy as a result of reduced apparent volume of the kernel. The trajectory of kernels in a crossflow matches that from pulsed jet literature.