Wenjun Zhong

Investigation of the cavitating flow in injector nozzles for diesel and biodiesel

In diesel engines, the cavitating flow in nozzles greatly affects the fuel atomization characteristics and then the subsequent combustion and exhaust emissions. At present the biodiesel is a kind of prospective alternative fuel in diesel engines, the flow characteristics for the biodiesel fuel need to be investigated. In this paper, based on the third-generation synchrotrons of Shanghai Synchrotron Radiation facility (SSRF), a high-precision three-dimension structure of testing nozzle with detailed internal geometry information was obtained using X-ray radiography for a more accurate physical model. A flow visualization experiment system with a transparent scaled-up vertical multi-hole injector nozzle tip was setup. A high resolution and speed CCD camera equipped with a long distance microscope device was used to acquire flow images of diesel and biodiesel fuel, respectively. Then, the characteristics of cavitating flow and their effects on the fuel atomization characteristics were investigated. The exper...

Large Eddy Simulation of the Internal Flow in Diesel Nozzles

The large eddy simulation was applied for the internal turbulent flow in diesel nozzles. Computational results were compared with those obtained from RANS(RNG κ-ε ) model. The influence of the meshing size on the simulation results were studied. The results showed that the meshing size has little effect on the flow structure when the model is adopted. Compared to the κ-ε model, the LES model results showed the obvious asymmetry and more complex turbulent flow structure. Furthermore, the LES model can capture a much wider range of vertical structures than the κ-ε model.