抄録
Dispersion of exhaust gas from an automobile model is studied experimentally by gas sampling method and smoke visualization in a wind tunnel. Exhaust emission is simulated using CO_2 and the gas concentration in the automobile wake is sampled by sampling probe and measured by a NDIR gas analyzer. The gas dispersion from an Ahmed body with 0°, 25° and 35° slanted back is measured. The measured concentration profiles show that gas dispersion behind the model depends strongly on the slant angle. In case of a 25° slanted model, the high concentration area is observed at roadside and it travels outward. This gas dispersion can be caused by the large-scale longitudinal vortex formed in the wake of the 25° slanted model. The concentration profiles behind the 35° slanted model also show large lateral dispersion that is attributed to the weaker longitudinal vortex in the wake. The smoke visualization using small aerosol agrees well with the measured concentration profiles.
