Experimental Study on the Snowfall Flow Control of Backward-Facing Steps Using a High-Durability Designed Plasma Electrode

Abstract

Using a high-durability designed plasma electrode (PA), the plasma actuation effect on both a two-dimensional backward-facing step flow (standard model) and an arc-shaped three-dimensional backward-facing step flow (arc model) was investigated experimentally. First, we searched for plasma operation control conditions suitable for the two-dimensional backward-facing step flow by carrying out experiments using a medium-sized circulating wind tunnel. Next, using the natural-snow wind tunnel of the Hokkaido University of Science, we examined whether an AC-driven PA can control snowfall flow. It became clear for the first time that the amount of snow accumulation can be reduced by more than 20% when the PA is driven at a dimensionless frequency of fH/U = 0.32, where f is the pulsed modulation frequency, H is the step height, and U is the mainstream velocity, and the duty ratio D (the time ratio of PA_ON to the total time when controlled by the pulsed modulation frequency) is equal to 1.0%. It was also confirmed that by masking the arc-shaped electrode parallel to the mainstream and using only the part perpendicular to the mainstream of the PA electrode, the amount of accumulated snow could be reduced by up to 20%. It has become clear that high-durability designed plasma electrodes can control the snowfall flow and reduce the amount of accumulated snow.