A Numerical Investigation Of High Pressure Fuel Spray Process Coupled With Nozzle Flow

The characteristic of fuel spray is one of the key factors that determine the performance of direct injection diesel engine. Therefore, the study about the principle of fuel atomization will provide requisite foundation theoretically. Since fuel atomization involves various intricate factors, such as cavitation flow, turbulent kinetic energy, flow instability, and aerodynamics etc., more investigation are needed to gain further insight into the principle of fuel atomization. Research results have indicated that internal flow in nozzle has an obvious effect on fuel atomization. Due to the insufficient understanding of the internal flow and the mechanism related to the coupling of internal flow and external atomization, above issues are receiving increasing attention and have become a research focus recently. Research on the internal flow and the mechanism of coupled internal flow and external atomization will be helpful for exploring the principle of fuel atomization, thus it is of great theoretical and practical significance.In this paper, firstly introduce the Schnerr-Sauer model, to establish the mathematical model regardinggas-liquid two phase flow in nozzle, while taking the cavitation flow into consideration. Based on this model, implement the numerical simulation for the process of the internal flow in a fuel injector with particular structure. Thus analyze the performance of the model about the internal flow through comparative experiments. According to the model establish, then investigate how the system parametersinfluence the internal flow, especially focus on the influence on the cavitation process inside nozzle. These parameters include nozzle’s diameter, length, injection pressure, and backpressure etc. Based on the simulation results, compute the parameters related to the flow in the cross section of the nozzle, and use them to compute the parameters of the model regarding coupled internal flow and external atomization.After analyzing the characteristics of the internal flow, furthermore introduce the cavitation collapse energy model, and establish the coupled math model regarding the internal flow and external atomization. This model can utilize the cavitationcollapse and turbulent kinetic energy’s impact on the external atomization. Then, validate the effectiveness of the model through comparison experiment. Results show that the cavitation collapse energy must be considered when the cavitation flow isintensive. Otherwise, the value of spray cone angle would be underestimated.Finally, utilize the established model to investigate various factors’influence on the process of fuel atomization. These factors include parameters of nozzle’s structure, injection pressure and backpressure etc. Analyze the mechanism of principle that how system’s parameters’ influence the atomization in both of macro and micro perspectives.