Characterization of a non-reacting spray from a hollow cone injector with GCI fuels using phase Doppler anemometry

The transient spray from a piezo-electric outwardly opening hollow cone injector was analyzed in a constant pressure chamber via 2D phase Doppler anemometry (PDA) technique. Measurements were performed at non-reacting conditions. Injection duration was set to 1.3 ms and two nathpha fuels, namely Haltermann straight run naphtha (HSRN) and J-24 light naphtha (LN), were used. Effects of ambient gas pressure and temperature on spray development were studied. Measurements were performed for analysis of droplet velocity and size development at 25 points about the hollow cone spray edge at three heights at various time delays. Selected measurement locations reveal the different behaviors of droplets inside and outside the spray cone. PDA results show that LN has a slightly higher maximum droplet velocity than the HSRN at the near-nozzle zone due to the lower density of LN and the maximum average droplet velocity decreases significantly with increasing ambient gas density. Droplet velocity vector fields and the DBI images show that circulation zones occur at the outer edge of the spray cone. SMD of the droplets was found to be in the range of 20 microns from this injector operated at 120 bar injection pressure and it gets smaller with increasing gas temperature. This is due to vaporization of droplet on its way to the measurement location. SMD of the droplets increases with increasing gas pressure. This is due to the decreased pressure difference supplied on injector; and the higher probability of droplets' collision and coalescence under higher gas pressure.