난류생성기 판 형상에 의한 난류화염 특성 연구

Abstract

The cross-shaped fractal grids which have RRBT(reduced ratio of bar thickness) and the hexagonal grid were used to generate various turbulent flow properties for low swirl flames. In the non-reacting flow field with the fixed bulk velocity at 10 m/s, decreasing RRBT induces the increasing turbulent intensity(ISUBU/SUB) with the delay in the location of lowest turbulent mean velocity(Ū) and highest turbulent fluctuation(ú) due to vortex shedding from the bar thickness. This phenomenon was well explained by a wake interaction theory using axial velocity profiles at the centerline. At various equivalence ratios for Hexa. and fractal grids, the characteristics of low swirl flames could be identified to a thin reaction zone regime in the Borghi – Peter regime diagram. Decreasing RRBT increases ISUBU/SUB in front of flame brush with increasing turbulent local displacement speeds (SSUBT,LD/SUB) via a linear correlation. The turbulent Reynolds number, ReSUBT/SUB composed of the ratio of length scale and velocity components induced the proportional trends in non linear relationship showing that the influence of the length scale ratio. The empirical correlation study of SSUBT,LD/SUB as a function of ReSUBT/SUB and ú/SSUP0/SUPSUBL/SUB was investigated to compare the influence of velocity and turbulent length scales ratio. The result of linear correlation equation with SSUBT,LD/SUB indicates the influence of velocity factors greater than ReSUBT/SUB through the exponential factor.