Development and application of the drop number size moment modelling to spray combustion simulations

Application of spray combustion simulation in DI diesel engine

“…Thus, at the neck of spray the flame growth is certainly disturbed by this gas circulation. The flux of backward gas velocity is relatively high in the spray neck The chemical reaction is dominant in the first period of combustion, and the turbulent reaction is carried on in the main combustion subsequently [5]. This effect of dominant reaction is also presented evidently in Fig.…”

“…The reaction rate obtained by calculating the pressure difference in combustion chamber reaches a peak at 2.5 ms after injection. In the simulation, the auto-ignition here is defined as the moment at which temperature is over 1000 K. Hence, the predicted ignition results here employing the PDF-EBU ignition model [5] is established at 2.13 ms and located at around 32.6 mm away from nozzle and 4.8 mm above centreline. This simulation corresponds to the experimental results of [13][14][15][16] that the ignition site of higher injection pressure, more than 100 MPa, appears in the leading vapour zone, while the ignition occurs in the periphery of liquid core for the lower pressure.…”

“…The reaction time scale is employed to relax the infinitely fast chemistry in the chemical equilibrium model. In the auto-ignition section, the PDF-Eddy Break Up ignition model [5] is adopted which performs successfully similar to the Shell ignition model. With regard to the comparison results, the simulation results are satisfactory in predicting the ignition delay time and flame development with the experimental results.…”

“…These moments employed in governing equations for spray are based on the moment-average quantities. In the crucial purpose of the present work, the mathematical models adopted for auto-ignition is the PDF-Eddy Break Up (EBU) ignition model [5]. The key concept of this ignition approach is to combine the chemical reaction rate dealing with low-temperature mode, and the turbulence reaction rate governing the high-temperature part by a reaction progress variable coupling function which represents the level of reaction.…”

Auto-ignition of diesel spray using the PDF-Eddy Break-Up model

“…Although the predicted results from both ignition models are satisfactory in predicting the ignition delay time, the ignition kernel location predicted by the PDF-EBU ignition model corresponds to the power-law scaling of Siebers rather than that by the Shell model. The more details of lift-off length discussion are given in Dhuchakallaya [58].…”