抄録
Experimental studies on the formation of a homogeneous spray and its ignition and combustion behaviors have been carried out by using microgravity conditions produced by a drop shaft. A rapid expansion apparatus was newly developed for the microgravity experiments. Homogeneous sprays were generated by rapid expansion of saturated fuel vapor-air mixtures. Microgravity conditions were applied to prevent the generated droplets from falling by gravity. Methanol and air were used as a fuel and an ambient gas, respectively. Telemicroscope and shadowgraphy were employed to observe the behaviors of the droplet formation and the flame propagation.
The homogeneous sprays up to about 30 µm in mean droplet diameter were generated successfully. It was experimentally shown that the mean droplet diameter, the total equivalence ratio and the ratio of liquid fuel to vapor fuel, which are important parameters for spray combustion, can be controlled independently with the rapid expansion apparatus. Two types of the flame propagating through a stationary homogeneous spray were observed under microgravity conditions.
