Burning Characteristics of Boron/JP10 Nanofuel Droplets

Abstract

Abstract The demand for higher volumetric calorific value of fuels for modern high performance aircraft has led to development of nanofuels that opens a promising future for enhancing the energy density of liquid fuels. This paper intends to study the effect of addition of boron nano-particles (NPs) on the burning characteristics of JP10 fuel droplets for various particle mass loadings (2%, 5%, 7% and 10%). Stable suspension of the NPs was achieved by adding Span80 and Tween80 as surfactant followed by ultra-sonication of the mixture. The fuel droplet was suspended on a horizontal quartz fiber. All experiments were conducted under atmospheric conditions. The droplet burning process was recorded using a high speed camera. The burning of pure JP10 and JP10 plus surfactant (without NPs) were also studied. In case of burning of pure JP10 fuel, the linear trend in time evolution of normalized droplet surface area suggested that the droplet burning follows the classical d2 – law and formation of bubbles inside the droplet was observed. However, these bubbles did not lead to puffing, which though occurred for JP10 plus surfactant (no NPs). This means that addition of surfactants, which has low burning rate, modifies the droplet burning process. In case of nanofuel droplet, burning occurs in different distinct stages for all mass loadings: initially the burning is smooth similar to pure fuel which is followed by intense periodical swelling and puffing in the later stages accompanied with ejection of secondary droplets from the parent droplet which burn separately. Finally, solo burning of NPs was evident for all cases. With increase in NPs loading from 2% to 10% vigorous surface oscillations and shattering of liquid masses were found which contributed to reduction in droplet lifetime. In such case the normalized droplet surface area showed periodic oscillations indicating departure from d2 – law.