外开式汽油喷油器喷雾特性研究

在定容弹内,采用纹影和激光Mie散射技术研究了外开式压电晶体汽油喷油器使用汽油、正丁醇和乙醇时的喷雾特性。结果表明,外开式喷油器喷油形成的空心圆锥状喷雾结构由线状油束组成。喷油背压对喷雾的宏观形态影响较大。随着喷油背压的升高,喷雾中油线间隙减小并最终消失,同时喷雾贯穿度与面积均大幅减小,但喷雾锥角基本不随背压、燃料种类和时间的变化而变化。此外,随着背压的升高,喷雾横向贯穿度的减小程度大于轴向贯穿度,但是横向贯穿度始终大于轴向贯穿度。粘度较大的乙醇和正丁醇的轴向贯穿度大于汽油。横向贯穿度与喷油产生的涡流有关。涡流尺度越大,则横向贯穿度也越大。

Spray Characteristics of An Outward-opening Gasoline Piezoelectric Injector

The spray characteristics of gasoline, n-butanol and ethanol injected from an outward-opening gasoline piezoelectric injector were investigated with Schlieren and laser Mie scattering techniques in a constant volume vessel. Experimental results showed that the hollow conical spray was composed of numerous tiny jets. The macrostructures of spray were affected by the magnitude of back pressure. With the increase of back pressure, the gap between two adjacent jets was decreased and finally disappeared. In the meantime, the penetration and projected area of spray were sharply reduced. However, the spray cone angel was nearly unchanged with time regardless of the magnitude of back pressure and fuel types. Furthermore, the decline of spray penetration was always larger in horizontal direction than that in vertical direction. But the penetration in horizontal direction was longer than that in vertical direction. The spray penetration in vertical direction for ethanol and n-butanol with relatively higher viscosity was longer than that for gasoline, which was contributed to the vortex formed during injection. The larger the scale of the vortex, the longer the penetration in horizontal direction was.