乱流予混合燃焼Ⅱ ―計測と直接数値計算―

抄録

To relate actual turbulent premixed flames observed in many applications with turbulent combustion diagram, experimental method for evaluations of turbulence characteristic length and Reynolds number based on Taylor microscale are discussed in detail. As for the hot wire anemometer, importance of energy spectrum and probability density function of velocity derivatives are shown for the accurate prediction of Taylor microscale. In the case of particle image velocimetry (PIV), spatial resolution should be in the same order of those of direct numerical simulation (DNS) of turbulence (less than 3-4 times the Kolmogorov length scale) to obtain Taylor microscale accurately. Current state and perspective of DNS of turbulence and turbulent combustion are discussed with feature trend of the fastest supercomputer in the world. Based on the perspective of DNS of turbulent combustion, possibility of perfect simulations of IC engine is shown. In 2020, the perfect simulation will be realized with 30 billion grid points by 1EXAFlops supercomputer, which requires 4 months CPU time. The CPU time would be reduced to about 4 days if several developments are achieved in the current fundamental researches.