Shintaro Sato

Electrohydrodynamic (EHD) force is used for active control of fluid motion and for the generation of propulsive thrust by inducing ionic wind with no moving parts. We propose a method of successively generating and accelerating ionic wind induced by surface dielectric-barrier-discharge (DBD), referred to as a DBD plasma actuator with multiple electrodes. A conventional method fails to generate unidirectional ionic wind, due to the generation of a counter ionic-wind with the multiple electrodes D

Collision dynamics of nanoparticles with a surface was studied by classical molecular dynamics simulations. Silver, nickel and silica were selected as the particle materials, and silver as the surface material. Particle sizes ranged approximately from 0.5 to 2 nm. The results indicate that particles with thermal energy at room temperature do not bounce off a surface, even when a very weak interaction potential between the particles and the surface is assumed. The loss mechanisms of the center-of

Abstract A relationship between electric potential distribution on a dielectric surface and electrohydrodynamic (EHD) force generation is experimentally investigated to improve the performance of dielectric-barrier-discharge (DBD) plasma actuators. Direct current (DC) biased repetitive pulses are applied to the DBD plasma actuator, which has two or three electrodes. Although the additional downstream exposed electrode has little effect on the electrical and optical characteristics of the DBD pla

An approach for electrohydrodynamic (EHD) force production is proposed with a focus on a charge cycle on a dielectric surface. The cycle, consisting of positive-charging and neutralizing strokes, is completely different from the conventional methodology, which involves a negative-charging stroke, in that the dielectric surface charge is constantly positive. The two-stroke charge cycle is realized by applying a DC voltage combined with repetitive pulses. Simulation results indicate that the negat

This study is focused on a reduced-order model (ROM) based on proper orthogonal decomposition (POD) for unsteady flow around a stationary object, which allows prediction with different object geometry as a parameter. The conventional POD method is applicable only to data with the same computational grid for all snapshots. This study proposed a novel POD methodology that performs on flow snapshots, including some time-series data of flow fields around objects of different shapes and numerically c

Abstract A novel method for fast simulation of discharge, which uses a plasma fluid model, is proposed with a focus on the small space-charge variation in the calculation of electric field. A simple scalar equation is employed in the proposed method to calculate the electric field variation instead of solving Poisson’s equation at every time step when the dielectric relaxation time is relatively large compared to the time step interval. We perform numerical simulations of surface dielectric-barr

Abstract Successful operation of a multi-stage dielectric-barrier-discharge (DBD) plasma actuator is demonstrated by operating it on voltage one order of magnitude lower than that of a conventional single-stage DBD plasma actuator. An applied voltage waveform of direct current (DC) voltage combined with high-frequency repetitive pulses is generated by a simple power system consisting of a DC power supply and silicon carbide metal-oxide-semiconductor field-effect transistors. The time-averaged fl

A new concept of electrode shape and arrangement is proposed to develop a multi-stage plasma synthetic jet actuator for the low-voltage operation. Exposed and covered electrodes, which have complicated shapes due to electrical wiring to the inner side of annular electrodes, are fabricated by an inkjet printing process using a silver nanoparticle-based ink. The plasma synthetic jet actuator developed in this study can be operated at 1000 V or lower. The discharge spreads uniformly from only the i

A novel dielectric barrier discharge (DBD) plasma-actuator module with an exposed electrode and two covered electrodes was developed to enhance electrohydrodynamic force generation based on the concept that it separates the ionization and acceleration processes. The conventional three-electrode configuration of the DBD plasma actuator suffers from unexpected spark discharge between the exposed electrodes, thereby failing to strengthen the electric field intensity for accelerating charged particl

Aerosols flowing in a tube under vacuum conditions, e.g., in semiconductor processing equipment, are often found to have a nonuniform profile due to low Reynolds number flow (Bae et al. 1998). A novel method to produce spatially uniform aerosols in a flow tube at low pressure has been developed. The method employs a counter-flow injection configuration. Two identical critical orifices of 200 w m in diameter are installed opposite each other in an aerosol mixing chamber. The opposing aerosol jets

Abstract A numerical simulation method for atmospheric-pressure surface dielectric barrier discharge (DBD) is presented using a structured curvilinear mesh that is fitted to a curved dielectric surface. The numerical method is based on the plasma fluid model with general coordinate transformation, which is widely used in the field of the computational fluid dynamics. The calculations of a potential distribution formed by a line electrode and a planar surface DBD are performed to confirm the vali

Abstract Simple models based on two-dimensional simulations are proposed to estimate intervals of periodically observed current pulses with a positive-going voltage in a dielectric barrier discharge plasma actuator. There are two distinct peaks in one streamer discharge; one is related to the formation of an ion cloud and the other is related to a filamentary discharge that is identified as a streamer. Simulation results show that the intervals of the current pulses depend on the slope of the ap