The Experiment To Investigate On Diesel Nozzle In Air Assistant

The Spray technology has been widely used in many fields of the human life and production, the progress of the combustion technology is closely related to the spray technology. In the fuel injection engine, the quality of fuel atomization affects the combustion process in cylinder, in turn, it will affects the engine performance, economy and emissions targets, so spray quality evaluation becomes more important.In order to explore whether the air assistant nozzle can be applied to the diesel engine or not, this paper studies the atomization quality of air assistant nozzle in the experimental method.This experiment established the test bench of hand pump spray, using the Malvern spray particle size analyzer and high definition digital camera measure spray characteristics parameters of different nozzle diameter, air assistant pressure and fuel injection pressure,such as Sauter mean diameter and spray angle.At last, we analyze and contrast the experimental results.According to the exploratory experiments, it can be seen the spray quality of the air assistant nozzle is better than that of diesel engine and gasoline engine nozzle in the same oil pressure. So we can expect to improve engine performance, fuel economy and emissions.Specific experimental results:(1) No matter it is low injection pressure experiment or the high injection pressure experiment, on the same study process of D32, D32 becomes small with the gas pressure increases, which to a certain extent will tend to stable, when we continue to increase air pressure, the influence of air assistant will be weaken; but D32 will increases with oil pressure increases.(2) For the experiment without air assistant, D32 is no less than 300μm,which is 30 ~ 40 times to the air assistant nozzle(16 ~ 22μm),it shows spray quality is poorer without air assistant than that of air assistant nozzle.(3) Compared to the number distribution and the accumulation volume distribution in different operating points, It can be seen clearly that the curve trend are consistent and all of curve peaks of fuel droplet size number distribution is located at very small particle size of more smaller than 20μm, the cumulative volume distribution curve in early phrase can even in a few micron particle size range,sauter mean diameter of D32 up to a dozen microns.(4) Spray angle is mainly determined by oilpressure, when oil pressure become bigger, the greater the spray angle become and the better the atomization quality becomes; The spray angle increases more obviously with air assistant than the without air assistant,and the spray cone Angle with air boost pressure increasing increases quickly first, then decreases slowly.(5) Through the flame stability experiment, it can show that air assistant nozzle jet is no significant impact on the internal flame stability of diesel engine combustion chamber.