Large Eddy Simulation of Non-Evaporative and Evaporative Diesel Spray in Constant Volume Vessel by Use of KIVALES

Large Eddy Simulation (LES) is applied to non-evaporative and evaporative diesel spray simulations. KIVALES, which is LES version of KIVA code, is used as the LES computational code. Modified TAB model is used as breakup model, and interpolated donor cell differencing scheme is employed to calculate convective terms. To validity LES simulation, LES results using KIVALES are compared with experimental results and simulated results with conventional RANS approach using KIVA3V res.2. The results show that the LES simulation of non-evaporative spray depends on the grid size in comparison with RANS simulation, and good agreement is obtained between experimental results and the LES results with fine grid (720,000 cells). Furthermore, asymmetric non-evaporative spray which has intermittency at the outer edge of sprays is simulated, since instantaneous turbulent flow field can be predicted directly in LES case. In evaporative spray simulation, although symmetric spray shape simulated by use of RANS, LES case shows the asymmetric shape and instantaneous structure of diesel spray, which has intermittency at the outer region of spray, and fluctuating distribution of gas velocity, equivalence ratio and gas temperature. In particularly, the vapor phase visualization of LES results by means of volume rendering is a good agreement in the evaporative spray image obtained by shadowgraph method.