Supply and clearance leakage characteristics of dimethyl ether in a marine high-pressure plunger pump

To promote the development of high-pressure pressurization components for dimethyl ether (DME), a coupled one-dimensional and three-dimensional simulation approach is employed to investigate the supply and clearance leakage characteristics of DME in a high-pressure plunger pump under supply pressures of 60–90 MPa and rotational speeds of 500–2500 r/min, with cavitation behavior in leakage flows examined. Results show that DME leakage during the compression stage prolongs the pressurization process, with the leakage-related delay being most pronounced at low rotational speeds. The cam angle range of the compression stage increases by approximately 2.5°CA for every 10 MPa increase in supply pressure. Leakage also accelerates the termination of the supply stage, causing an earlier transition to the expansion stage. At 500 r/min, the supply volume and specific energy consumption of DME are approximately 58% and 2.03 times those of diesel, respectively, increasing to 92.47% and decreasing to 1.26 times at 2500 r/min. During leakage, diesel remains in the liquid phase, whereas DME undergoes pronounced cavitation within the annular groove and cylindrical channel, primarily driven by flow separation and local pressure fluctuations. Increasing the return pressure and reducing the inclination angle of the annular groove effectively suppress cavitation intensity, reducing the vapor volume fraction by more than 65% and thereby mitigating cavitation risk in high-pressure plunger pump operating with DME.