Dielectric Barrier Discharge Actuators to Control Goertler Vortices on a Swept Wing

Narrowband excitation of fin buffeting is known to exist on several modern aircraft configurations at high angles of attack. For a fixed angle of attack and model geometry, narrowband peak frequency is a linear function of freestream speed. Under these conditions, counter-rotating vortex pairs conforming to the Goertler vortex mechanism are known to develop and amplify in the flowfield over the wings. This phenomenon is explored for relevance to reverse flow over rotor blades at high speeds as well. A 42-degree delta wing with rounded leading edges is used in a low-speed wind tunnel to confirm the phenomenon. The presence of a non-zero yaw angle can increase the strength of the Goertler vortices and also change the location of maximum intensity. Small fences on the surface have been shown to eliminate these narrow-band fluctuations. Dielectric Barrier Discharge plasma actuators offer a possible means to eliminate the narrowband excitation without obtrusive surface fences. An array of such actuators is used to generate counter-rotating vortices. Incense smoke entrained into the flow is illuminated with a laser sheet from a laser pointer. Video images are used to capture velocity in the potential flow region around the vortices. The induced velocity is used to calculate vortex strength. Scaling laws are used to estimate the frequency of the actuators, as well as the magnitude of the velocity. The scaling estimation shows that a plasma actuator is viable for model-scale configurations. Continuing experiments for the final paper plan to apply the actuator under delta wing high angle of attack operation.

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Abatement of Toluene by Reverse-Flow Nonthermal Plasma Reactor Coupled with Catalyst

Catalysts ◽

10.3390/catal10050511 ◽

2020 ◽

Vol 10 (5) ◽

pp. 511 ◽

Cited By ~ 3

Author(s):

Wenjun Liang ◽

Huipin Sun ◽

Xiujuan Shi ◽

Yuxue Zhu

Keyword(s):

Dielectric Barrier Discharge ◽

Barrier Discharge ◽

Reverse Flow ◽

Plasma Reactor ◽

Nonthermal Plasma ◽

Toluene Degradation ◽

Dielectric Barrier ◽

Reactor Temperature ◽

Dbd Reactor ◽

By Products

In order to make full use of the heat in nonthermal plasma systems and decrease the generation of by-products, a reverse-flow nonthermal plasma reactor coupled with catalyst was used for the abatement of toluene. In this study, the toluene degradation performance of different reactors was compared under the same conditions. The mechanism of toluene abatement by nonthermal plasma coupled with catalyst was explored, combined with the generation of ozone (O3), NO2, and organic by-products during the reaction process. It was found that a long reverse cycle time of the reactor and a short residence time of toluene decreased the internal reactor temperature, which was not beneficial for the degradation of toluene. Compared with the dielectric barrier discharge (DBD) reactor, toluene degradation efficiency in the double dielectric barrier discharge (DDBD) reactor was improved at the same discharge energy level, but the concentrations of NO2 and O3 in the effluent were relatively high; this was improved after the introduction of a catalyst. In the reverse-flow nonthermal plasma reactor coupled with catalyst, the CO2 selectivity was the highest, while the selectivity and amount of NO2 was the lowest and aromatics, acids, and ketones were the main gaseous organic by-products in the effluent. The reverse-flow DBD-catalyst reactor was successful in decreasing organic by-products, while the types of organic by-products in the DDBD reactor were much more than those in the DBD reactor.

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