Weidi Huang

The Influence of Diesel Nozzle Structure on Internal Flow Characteristics

Based on X-ray CT scan technology in Shanghai Synchrotron Radiation Facility (SSRF), the inner structure of a side jet single-hole nozzle was obtained and its parameters around the inlet circle were measured. Further researches were carried out with the flow rate test bench about the influences of structure parameters symmetry on the internal flow characteristics and cavitation. Results showed that: the size deviation of inlet diameter, outlet diameter and nozzle length around the inlet circle are relatively small, while the inlet rounding radius is obviously distributed unevenly. Because of that, the cavitation had already showed up when the injection pressure was 40 MPa and the critical cavitation number equalled to 1.032, which should not take place according to the traditional theory. Thus, when relative studies are carried out, it is important for researches to take fully consideration of the size deviation of nozzle structure parameters, especially for the inlet rounding radius, to achieve more reliable conclusions.

Applications of synchrotron X-ray micro-tomography on nondestructive 3D studies of diesel nozzle internal micro-structure

In diesel engines, the fuel spray breakup and atomization process have tremendous dependence on the nozzle internal geometries, then the performance, fuel consumption and emission of the engines will be affected. Based on the synchrotron X-ray micro-tomography, the three-dimensional models of the diesel nozzles were established. Then the internal geometries of the nozzle orifices, such as the diameter, the length and the inlet chamfer radius of the orifice, can be measured, making it possible to analyze the impact of different nozzle orifice processing methods. Meanwhile, the nozzle digital models were successfully applied to simulate the internal flow of high pressure fuel inside the nozzle; the effects of nozzle geometries on internal flow characteristics have been analyzed. The results show that these works are significant to the promoting of diesel nozzle processing technologies, and the revealing of high pressure fuel spray breakup mechanism.