In this study, the flow of fluid in the fuel injector nozzle of a Diesel engine was simulated under steady-state and transient conditions using ANSYS Fluent. At first, a nozzle for which experimental results were available was simulated. Then, validating the results, the $$ k - \varepsilon $$ k - ε turbulence model and the Schnerr–Sauer cavitation model were selected for the numerical simulation of a real four-hole fuel injector nozzle. In order to reduce the computational costs, only a quarter of the nozzle was modeled and the flow rate and discharge coefficient were obtained for different pressure differences. Three different seats with various needle lifts were analyzed in the steady-state case. Next, the problem was addressed under transient conditions and the results were compared with the steady-state case. Transient analysis has been performed by using ANSYS Fluent layering dynamic mesh with using UDF code for the needle lift. Ultimately, the impact of the needle lift frequency was investigated on the formation of vapors in the nozzle under transient conditions. The results of the numerical simulation show that, in addition to the discharge coefficient, needle lift, the seat design, and the frequency of the needle lift also affect the location and the size of the cavitation.

中文翻译：

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针提升和阀座设计对柴油喷油器喷嘴稳态和瞬态流动影响的数值研究

在这项研究中，使用 ANSYS Fluent 在稳态和瞬态条件下模拟柴油发动机喷油嘴中的流体流动。首先，模拟可获得实验结果的喷嘴。然后，验证结果，选择$$ k - \varepsilon $$ k - ε 湍流模型和Schnerr-Sauer 空化模型对真实的四孔喷油嘴进行数值模拟。为了降低计算成本，仅对喷嘴的四分之一进行建模，并获得不同压差下的流量和流量系数。在稳态情况下分析了具有不同针升程的三种不同座椅。接下来，该问题在瞬态条件下得到解决，并将结果与​​稳态情况进行比较。瞬态分析是通过使用 ANSYS Fluent 分层动态网格并使用 UDF 代码进行针提升来执行的。最后，研究了针阀提升频率对瞬态条件下喷嘴中蒸汽形成的影响。数值模拟结果表明，除流量系数外，针阀升程、阀座设计和针阀升程频率也会影响气蚀的位置和大小。