Acoustically disturbed fuel droplet combustion

Abstract

This paper is concerned with the influence of acoustic waves on the process of petrol and diesel fuel single droplet combustion. The process can be described by the mathematical model: t 0 = D 0 2 K , where t 0 is the time of complete droplet combustion; D 0 is the initial droplet diameter and K is the combustion constant which characterizes the conditions of combustion and fuel properties. The process of droplet combustion is therefore controlled by the value of K. The higher the value of K, the more intensive the resulting combustion, so that the combustion process exists for a shorter time. A single droplet combustion method determined the influence of acoustic waves frequency and power on the value of the combustion constant K. The intensity of the combustion was detected by a photodiode and recorded by an oscilloscope. The investigation was carried out within the range of frequencies 20 Hz–5 kHz. The acoustic wave generator power was between 0 and 5 W, which corresponded to sound levels L = 40–115dB. The most significant effect of frequency on the value of K was observed between 120 and 300 Hz and L = 100–115 dB at which the value of K increased by about 14%. In the range of 20–50Hz, the value of K decreased below the value of K 0 (non-disturbed combustion) before increasing to achieve a maximum value equal to 114% of K 0 at 275 Hz. At frequencies greater than 600 Hz the value of K decreased and then kept constant at 108% of K 0 up to 5 kHz — the limit of experiment.