Enhancing breakup of liquid sheets in quiescent air using MHz-order acoustic waves

Further enhancements in aircraft engine development will rely in significant part on facile control of fuel spray characteristics like droplet size, size distribution, and intact jet-to-droplet length. Aircraft engines suffer from extreme trade-offs when exceptional performance is needed. For example, high fuel consumption, poor propulsive efficiency, and a significant increase in both noise and a radar-visible exhaust gas plume often accompany high-thrust engine states. We present a novel nozzle pintile design that utilizes a single-crystal piezoelectric ultrasonic device to induce more rapid and complete fuel atomization. Preliminary results of experiments where the liquid sheets are injected into quiescent air show that the device increases the efficiency of fuel burning even in harsh environments resembling that of a combustion engine. Specifically, we show that at Weber numbers applicable to fuel flow rates, the device increases the amount of smaller droplets and shrinks the distribution of droplet sizes. Furthermore, these results appear as the liquid’s surface tension decreases. With these promising results, we plan to test design variations.