Various techniques are available to reduce exhaust pollutants from diesel engine. Out of these techniques, SCR technique to decrease NOx is an aftertreatment system by spraying urea to exhaust gas. In the case of SCR technique for vehicles, mixer is installed and used to improve the effect of aftertreatment. This study analyzed the effects according to the number and the angle of rotational mixer blades. As a result, the case of installing mixer indicated the increase of overall uniformity. Also, the increase of mixer blade number showed the increase of uniformity and the decrease of mixer blade angle caused to increase the uniformity as well. Furthermore, the stronger the turbulence intensity, the shorter being reached to the target uniformity. However, because the installation of mixer increases the pressure drop, the optimization model was suggested by setting specific pressure drop.

mixer, SCR system, CFD, internal flow, NOx, uniformity.