Analysis of Injection Characteristics and Structural Reliability of Marine Methanol Fuel Injectors

Nowadays, the energy transition is at the most critical moment. In order to achieve the emission reduction target of ships, a form of boosting piston inside methanol fuel injector has been carried out. The physical property fluctuations and phase change of methanol under high pressure have been considered in the design phase. 1D-3D coupling method is used to comprehensively evaluate the performace of the injector. To this end, an Amesim simulation model is established to systematically study and analyze the injection characteristics. The injection performance of the injector under four typical loads are calculated, which is evaluated from the perspectives of injection quantity, injection duration, valve response, and leakage of boost components. In the nozzle block, the cavitation intensity of methanol is stronger than that of diesel. To reduce the possibility of cavitation erosion, as a consequence, a CFD model is established to optimize the structure of nozzle components. By adding rounded corners at the inlet of the nozzle to weaken cavitation intensity and improve injection stability. Furthermore, the mass flow rate of optimized nozzle can be improved by at least 30%. The equivalent stress and deformation of the nozzle and needle valve body under alternating thermal stress are calculated to ensure that they meet the design requirements(<1600MPa). The safety factor of fatigue also meets the requirements(>1.1). Through the complete design and simulation work, we can break through the problem of insufficient technical reserves of marine methanol injectors in China and assist in the development of low-carbon engines for self-owned brand.