Abstract:

The fuel injector is the key component of the marine diesel engine, and the diameters of the injector nozzle and the control chamber oil inlet and outlet, which are typical microchannel structures, are generally between 0.2 and 0.5mm. During high pressure injection, the cavitation phenomenon in the channel seriously affects the reliability of diesel engine. The choice of turbulence and cavitation models is the key to study the above cavitation problems using the numerical calculation methods. Based on the Winklhofer microchannel fuel test, three representative turbulence models and two cavitation models were used to construct the microchannel model, and the simulated results were compared and analyzed with the test results. The results show that the pressure gradient values obtained from the two combinations of RNG k-ε+ZGB models and RNG k-ε+SS models are similar to the experimental data with an error of less than 7%; the cavitation distributions calculated by the different model combinations are different; the outlet mass flow rates obtained from Realizable k-ε+ZGB models and RNG k-ε+ZGB models are consistent with the experimental; in the range of pressure difference from 19 bar to 85 bar, and the outlet mass flow rate obtained from the Realizable k-ε+ZGB model and the RNG k-ε+ZGB model matches the trends of the experimental data, and the error is less than 4%. In the caculation of cross-sectional flow rate, the calculated error of RNG k-ε+SS model is minimum with the error of less than 10%.

Key words: marine diesel engine, fuel injector, cavitation, microchannel, model comparison