CARS Temperature Measurements in a Droplet Stream Flame

Abstract

This paper describes measurments of the local temperature field near a combusting stream of methanol droplets using coherent anti-Stokes Raman scattering (CARS). Synchronizing the CARS measurements with the droplets in the stream allows correlations between the temperature field and the droplet position. These measurements describe the thermal structure of the droplet stream flame and can help validate detailed spray combustion models. The diameter of the droplets in the stream is 120 pm, which is comparable to the droplet size in a practical spray. The droplet spacing is approximately 1.0 mm (8 droplet diameters). The CARS measurements indicate a flame surrounding the droplet stream located I mm (8 droplet diameters) from the stream centerline. The temperature profile shows a local minimum temperature a the stream centerline. Moving radially outward from the centerline, the temperature rises at the flame (about 2000 K), and then falls gradually to room temperature. The local minimum temperature is more pronounced on lines through droplet centers than on lines between adjacent droplets. The results also show that the temperature profile between adjacent droplets becomes more uniform as the droplets move downstream.

Key words:

• CARS
• temperature
• droplets
• flame