Experimental and numerical investigation on the interaction between ar flow channel and ar plasma jet at atmospheric pressure

In this paper, the interaction between Ar flow channel and atmospheric pressure plasma jet (APPJ) is investigated quantitatively by combining 3-D species transport simulation and optical schlieren observation together. The turbulence model, gravity force, and electrostatic force model are included into the Ar flow channel simulation. It is found that, with the increment of the Ar flow rate, the plasma plume reaches the maximum length at 3.5 L/min and then decreases sharply, which is corresponding to the Ar flow status. The simulations of the Ar flow channel show good agreement with the captured schlieren images. At small flow rates, the Ar flow channel bends downward due to the gravity. Under laminar flow, the high Ar mole fraction region near the axis of the Ar flow channel increases with the flow rate. However, the Ar flow presents as twist and radial diffusion, and the Ar mole fraction decreases rapidly when the Ar flow transits into turbulence, which leads the length of the Ar plasma plume to decrease sharply correspondingly. The plasma plume bestows the Ar flow channel a forward momentum, which decreases the curvature of bending downward and reinforces the twist and instability of the Ar flow channel under turbulence flow. By coupling the optical emission spectra and flow channel investigation together, it is revealed that Ar APPJ propagates along the core of the conelike flow channel. The Ar mole fractions at the head of the plasma plume are about 0.985 and 0.45 under laminar and turbulence flow, respectively.