A Method for Predicting Penetration Distance of Multiple Injection Spray in Diesel Engine

Abstract

The object of the present invention is to provide a method for predicting the spray penetration distance of multiple injections of diesel engines, which can equate the variable injection curve of multiple injections into a steady-state jet with mass-average injection velocity at any instant. The Stokes number is related to its mass-averaged velocity so that the Stokes number of each spray responds in time to changes in its injection rate. The particle response time of the two sprays before and after is calculated, and the effective jet velocity at the tips of the two sub-sprays at this moment is obtained according to the isolated droplet theory. The effective injection velocity of the two sub-spray tips at any instant is coupled with the spray penetration analytical model, and the overall spray penetration at this moment is obtained by judging the multiple injection spray tips. The present invention adopts the variable time upper limit integral to calculate the mass average injection velocity, so that the influence of the fuel injection rate change is applied to the development process of the spray penetration distance in time; the calculation of the spray penetration distance under the condition of variable fuel injection is realized by the analytical method, which significantly improves the Calculate speed.

Description

technical field [0001] The invention relates to a diesel engine prediction method, in particular to a diesel engine injection prediction method. Background technique [0002] With its great advantages in energy saving and emission reduction, multiple injection technology has been developed rapidly in diesel engines. At present, this technology has more injection times and more flexible fuel injection rules, which greatly improves the oil-gas mixing process in the diesel engine cylinder, optimizes the spray combustion characteristics, reduces the generation of nitrogen oxides and soot from the root, and significantly improves Fuel utilization. Therefore, multiple injection technology is of great significance to improve the performance of diesel engine and promote its sustainable development. [0003] Spray penetration is an important parameter commonly used to measure the mixing effect of oil and gas in a diesel engine cylinder. It directly represents the macroscopic distri...

AI Technical Summary

Problems solved by technology

However, there is still no research on the time-dependent characteristics of the second spray penetration of multiple injections, so it is still necessary to determine the quantitative relationship between the two in order to more quickly and accurately predict the change law of the spray penetration of multiple injections, and provide a basis for diesel engine regulation. Fuel injection strategy and optimized spray mixing process provide theoretical analysis and engineering evaluation tools

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