Abstract:
The PIV technique was applied to study the turbulent characteristics of the spays through the swirl injector and the double-jet holes injector which belong to the typical spray models called liquid-film spray and cylindrical spray respectively. The Spatial Turbulent Intensity (short for “I”) and the Turbulent Integral Length Scale (short for “ILS”) were used as parameters to analyze the turbulent characteristics of the two typical sprays. The result indicated that in the whole spray process, the distributions of I-values for the two kinds of sprays were diffuser than the distributions of speed-values, and the I-values were mainly distributed on the regions of the upside, downside and the root side of the spray flow fields. With the spray is continuing the I-value of the spray flow field, the I-value of the spray flow fields became higher and its distributions mainly concentrated in the regions of the non-front for the swirl spray and the non-front, non-central line for the double-jet spray. In order to simulate the ILS distribution more convenient, the ILS-value of every point of the spray flow field was decomposed into 4 components: Lxx, Lyx, Lxy, Lyy. Begining with the injectors spraying, at the time of 1.5ms and 4ms, the Lxx value of the swirl spray was higher than the double-jet spray and was also higher than the 3 other components at the same time; the local values of the Lxx reached the scales of 6mm(1.5ms) and 7mm(4ms). At the time of 8ms, the distributions of all components for the swirl spray were diffuser than the double-jet spray; at the same time, the distributions including values and integralities of Lyx and Lxy were completely contrary. In the whole spay process, the distributions of Lyx for the two sprays were obviously lower and less integrated than the 3 other components respectively.