# Experimental Characterization of Two-Phase Aerated Liquid Ethanol and Jet A Spray Flames +
## 2 Experimental Setup
Ethanol angles were consistently larger than their Jet A counterparts, but the differences between ethanol and Jet A angles did not exceed 10 degrees as shown by the difference lines in Figure 2:1 The ignited spray angles were observed to typically be larger than the non-ignited spray angles for ethanol, while for Jet A the ignited sprays generally had smaller spray angles than their non-ignited counterparts. This finding may indicate that the Jet A spray consumed fuel more quickly than the ethanol spray, while the ethanol flame's effect on the dynamics of the air in and around the spray may have had the effect of widening the overall spread of the droplets prior to their ignition; however, the visual measurement basis of the spray angle analysis method and small sample size of these results should be acknowledged as limits on drawing extensive conclusions regarding the differences in the ignited and cold-flowing spray angles, and future investigations focusing on the spray angles might elucidate the phenomenon. Figure 2:2 \(Cont.\)  
Figure 2:3 _Cont._  
Figure 2:4 Mie scattering images of ethanol spray at four equivalence ratios. The O\({}_{2}\) flow rate was fixed at 0.4 L/min. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Fuel** & \(\phi\) = 6.56 & \(\phi\) = 7.55 & \(\phi\) = 8.06 & \(\phi\) = 10.9 \\ \hline \multirow{2}{*}{Non-ignited spray angle (degrees)} & Ethanol & 56 & 61 & 62 & 66 \\  & Jet A & 57 & 59 & 57 & 63 \\ \hline \multirow{2}{*}{Ignited spray angle (degrees)} & Ethanol & 58 & 63 & 64 & 71 \\  & Jet A & 54 & 57 & 60 & 62 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Mie Scattering Spray Cone Angles. Figure 8: Mie scattering images of Jet A spray at four equivalence ratios. The O\({}_{2}\) flow rate was fixed at 0.4 L/min. Flame chemiluminescence of C\({}_{2}\)*, CH*, and CO\({}_{2}\)* was captured for both fuels in each of the four equivalence ratio cases. Averaged images were produced from 100-shot sequences as with the Mie scattering data. Figure 10a-c show the emissions for ethanol, and Figure 11a-c show the emissions for Jet A. For a particular fuel, the four equivalence ratio images per emission product have each been normalized by the maximum value of the four images in that emission product set. The emission intensity was low enough to be close to the background in the cases of C\({}_{2}\)* and CO\({}_{2}\)* with ethanol, resulting in noise from standout pixels which interfered with the normalization; those image sets were thus further normalized to a threshold percentage of their maximum values to negate the pixel noise. The reaction zone is defined by the high-intensity edges of the chemiluminescence emissions; therefore, the average flame height above the nozzle (assumed in this analysis to begin when the emission intensity reached \(\sim\)30% of the maximum intensity of the full image) was observed to be -7.5 mm based on the heights of the emission image groups for both fuels. The exceptional case of CO\({}_{2}\)* for Jet A showed the emission only reaching the 30% intensity threshold at a height of around 10 mm or higher above the nozzle, but otherwise the emissions appeared to reach the threshold at -7-8 mm. Additionally, the flame edges exhibited movement further from the center of the images as equivalence ratio was increased for both fuels. The enlargement of the spray angle with increasing equivalence ratio observed in the Mie scattering data may be correlated to the widening of the flame edges in the chemiluminescence emissions, suggesting that liquid was spread over a larger volume as the equivalence ratio was raised. Additionally, correlation of increasing equivalence ratio with the increase in the size of the core region of the flame may indicate that oxygen deprivation in the center region also increased and pushed the flame reaction zone to encompass a larger area until achieving sufficient oxygen draw from the surrounding air.