Experimental Study on the Penetration of Diesel and Biodiesel Spray Liquid Emerging from an Equilateral Triangular Orifice under Evaporative Conditions

This paper reports the results of an experimental study on the liquid phase characteristics of the biodiesel and diesel discharged from an equilateral triangular orifice and a circular orifice under different injection conditions by Mie-scattering imaging. The results revealed that the biodiesel liquid penetration length was longer than that of diesel under the same injection conditions. In addition, the increase of the chamber pressure was expected to enhance the interaction between air and fuel, resulting in the acceleration of the liquid phase breakup process. Moreover, with increasing chamber temperature, the liquid penetration of biodiesel was reduced less than that of diesel. This was due to the high surface tension and viscosity of biodiesel which inhibited the chamber air entrainment and suppressed the liquid breakup process. Accordingly, the higher probability of shorter diesel liquid penetration length indicated better air-fuel mixing than that of biodiesel. Besides, the triangular orifice liquid length was shorter than that of the circular orifice. And the stabilized liquid cone angle from the circular orifice was larger than that from the triangular orifice, indicating that using an equilateral triangular orifice has the potential to improve the air-fuel mixing process.