The fuel injector is a critical component of the internal combustion engine. The diameters of the injector nozzle and the control chamber’s oil inlet and outlet are generally between 0.2 and 0.5 mm, which are typical microchannel structures. During high-pressure injection, the cavitation phenomenon in the channel seriously affects the reliability of the internal combustion engine. The choice of turbulence and cavitation models is the key to investigate the cavitation in the microchannel by using numerical methods. Based on the Winklhofer microchannel fuel experiment, five representative turbulence models were used to construct a microchannel model, and the results were compared and analyzed with the experiment. The results show that the pressure gradient values obtained from the combination of RNG k-ε and ZGB models were similar to the experimental data, with an error of less than 6%. The cavitation distribution calculated from the combination of LES and ZGB models was most consistent with the experimental observation data. The outlet mass flow rate obtained from the LES and ZGB models matched the trend of the experimental data in the pressure difference range of 19 bar to 85 bar, with an error of less than 2%. For the cross-sectional flow rate calculation, the RNG k-ε and ZGB models had the smallest calculation errors, with errors below 11%.

The homogeneous field measurement of internal flow and spray of internal combustion engine injector nozzles under high pressure has always been one of the difficulties in experimental research. In this paper, an actual-size aluminum alloy nozzle is designed, and the simultaneous measurement of internal flow and near-field spray is successfully realized with the help of synchrotron radiation X-ray phase contrast imaging technology under an injection pressure of 30~90 MPa. For a 0.25 mm aperture nozzle, different radii of the inlet corner can induce different cavitation layer thicknesses, and the measured flow section shrinkage ratio is 0.70. The flow characteristics in the nozzle are entirely connected to the jet characteristics, indicating a tight correlation between internal flow and jet morphology. Finally, the internal cavitation of the nozzle was studied by the CFD simulation, and the simulation results are in good agreement with the experiment.

This study investigates a prediction model for the cycle injection quantity in a high-pressure common rail injector under a transient thermal boundary. The results show that the transient temperature increase curve calculated by the mathematical model of the common rail injector under adiabatic flow is significantly different from the experimental data. A non-isothermal model of the injector coupled with heat transfer is established, which considers the actual heat transfer phenomenon. The excellent agreement between the new calculation results and the experimental data confirms that the fuel injection process of a common rail injector comprises the coupled phenomena of fuel heating and heat transfer. Based on the established simulation model, it is found that in the continuous injection process of the injector, owing to the thermal effect of injection, the cycle injection quantity decreases gradually with an increase in the injector working time and then stabilizes. Under the condition of an injection pulse width of 1.2 ms and frequency of 100 Hz, when the injection pressure increases from 140 MPa to 300 MPa, the reduction in the cycle injection quantity increases from 3.9% to 7.8%, because the higher injection pressure results in higher transient heat at the nozzle holes. In the work of common rail injector assemblies, to achieve more accurate control of the cycle injection quantity, it is necessary to include the correction of a decreasing cycle injection quantity caused by transient heat in the electronic control system.

Cavitation flow inside an injector control valve significantly affects the injection performance and operational reliability of diesel engines, and the selection of turbulence and cavitation models is crucial for accurately predicting cavitating flows. To evaluate the predictive performance of different model combinations, a numerical model was established based on the Winklhofer microchannel experiment. Three large eddy simulation (LES) subgrid-scale (SGS) models were coupled with three cavitation models, and their performance was assessed by comparing the predicted outlet mass flow rate, centerline pressure distribution, and cavitation distribution with the experimental results. The results show that the outlet mass flow rate increases with the inlet–outlet pressure difference. When the pressure difference reaches approximately 70 bar, the growth rate decreases significantly, indicating the onset of typical cavitation-induced flow choking. Under low pressure differences, the prediction results of different model combinations are generally similar, whereas significant discrepancies are observed under high-pressure-difference conditions with intense cavitation. In terms of mass flow rate prediction, the Dynamic Smagorinsky + FRP model combination shows the best agreement with the experimental results in the pressure difference range of 70–85 bar, with an error of 3.06%. For pressure distribution prediction, the Dynamic Smagorinsky + FRP and Smagorinsky + FRP model combinations exhibit relatively smaller errors than the other combinations. The cavitation distribution results indicate that, compared with the LES subgrid-scale model, the cavitation model has a more pronounced influence on the extent and evolution of the cavitation region. Overall, the Dynamic Smagorinsky + FRP model demonstrates the best comprehensive predictive performance. Furthermore, this model was applied to the simulation of cavitating flow in a two-dimensional injector control valve, and the predicted results agree well with the visualization experiments. The present study provides a useful reference for the numerical simulation and structural optimization of cavitating flows in injector control valves.

Comprehensively promoting curriculum ideological and political construction is a strategic measure to carry out the fundamental task of cultivating morality and cultivating people, and curriculum ideological and political construction is an important task to comprehensively improve the quality of personnel training. In order to fully implement the ideological and political resource database of specialized courses, this paper discusses in detail how to construct diversified and informationized ideological and political resource database of specialized courses from the perspective of necessity, purpose and method of construction.