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One of the useful ways to measure the effect of the flow control devise is to use the wall-shear stress sensor to measure the wall-shear stress directly. The sensor used in this paper measures the wall-shear stress, which is influenced by the flow control devise. In this paper, the wall-shear stress of the plane shear layer with the plasma synthetic jet actuator (PSJA) is investigated. PSJA is a flow control device composed of electrodes with A.C. signal. The actuator uses electrohydrodynamic (EHD) effect and induces flow around the electrodes. PSJA has great advantage such as miniaturization, maintenance free, and easy to control compared to other actuators. In this paper, the wall-shear stress of plane shear layer in a low-speed turbulent wind tunnel is observed to measure the effect of the PSJA. The results show that the PSJA changes the flow condition of shear layer by accelerating the flow in shear layer. The wall-shear stress reduces and increases according to the displacement of the wall-shear stress sensor and the actuator.

This paper describes humidity characteristics of Plasma Synthetic Jet Actuator (PSJA). PSJA is flow control device using the Electro Hydro Dynamic (EHD) effect of the glow-discharge. PSJA can be downsized, controlled easily, and has quick control response. Though the flow control around an airfoil with PSJA is mainly studied, its characteristics have not been clarified. So, it is necessary to investigate humidity characteristics of induced flow by PSJA. In this paper, the induced flow from PSJA was measured in the different relative humidity. The experimental results show that the effect of induce flow by PSJA had decreased with increase relative humidity. Therefore, when PSJA was used, relative humidity becomes an important parameter.

This paper presents an investigation of PWM control with plasma synthetic jet actuator (PSJA). PSJA is an electric device designed for flow control using electrohydroninamic (EHD) effect. PWM control (ON-OFF control to glow discharge periodically) was proposed to induct waves which are subjected to lower frequencies than the frequency to drive the PSJA. The results show that the decrease of drag such as maximum velocity deficit and RMS has dropped by selecting a proper frequency in an angle of attack 15°, where the decrease of drag wasn't observed without PWM control. The result has indicated that the most effective frequency exists for separation control with PWM.

Flow on an airfoil was investigated with plasma synthetic jet actuator. Plasma synthetic jet actuator is a flow control device, which is composed of two electrodes with a.c. signal, using electrohydrodynamic (EHD) effect and induces flow around the electrodes. Plasma synthetic jet actuator has some important advantages ; for example, miniaturization is possible, mechanical maintenance is almost free. Therefore it is expected to apply for flow control around an airfoil. In this study, to observe behavior of the plasma synthetic jet actuator, experimental study was conducted. A NACA0012 airfoil, in which plasma synthetic jet actuator is embedded, was chosen, and the wake velocity behind airfoil is measured by hot wire anemometer with or without operating the actuator.

This paper presents investigation of optimum location of plasma synthetic jet actuator (PSJA) that is an electric device designed for flow control around an airfoil using electrohydrodinamic (EHD) effect. New turbulence model, that is, “pseudo viscosity model” is proposed to describe effect of PSJA in N-S simulation, witch is aimed to achieve low computational cost. Computational result qualitatively agrees with experimental one about wake velocity profile of wing. Next, separation delay control with another type of PSJA is simulated. Knowledge obtained from present simulations about optimum location of PSJA also agress with it obtained from experiments stretch several years.

Flow induced by plasma synthetic jet actuator (PSJA) is investigated using computational fluid dynamics. PSJA is a flow control device and induces flow using electrohydrodinamic (EHD) effect around electrodes exerted AC voltage. Its mechanism is not well known, but it is said that paraelectric force proportioned to gradient of electric energy density is important on PSJA. In this paper, numerical simulation is documented to discuss mechanism of PSJA with considering only paraelectric force as EHD effect. The numerical results agrees with flow pattern observed on experiments. The difference between two types of PSJA, that is, directed type PSJA and non-directed one is indicated.

In a thermal convection field constrained by right and left insulated walls, stable multiple solutions easily exist. In the case of a two-dimensional cavity with aspect ratio of 1.5, whose upper wall is cooled and lower wall is heated at a constant temperature, the two modes of thermal convection cell pattern are stable at Rayleigh number Ra of 2.0 × 105. That is, one-cell-mode and two-cell-mode. However, as Ra increases to 3.5 × 105, both modes become unstable, and appear in similar probability. The objective of this work is to demonstrate the possibility of controlling convection patterns under unstable conditions. We found that estimation using artificial neural network is effective to increase the probability of obtaining a desired mode, even in the slightly higher Ra of 2.5×105.

Numerical simulations of a reacting 2-D plane shear layer are performed using the fast mixing model which we proposed in a prior paper. Shear flow is simulated by a Lagrangian particle tracing method with a stochastic model based on turbulent statistical quantities. The chemical process used here is "A+B→P", ignoring heat release. The validity of this model has been investigated for the following cases : 1) effect of reaction rate, 2) effect of lean-to-rich reactant ratio, 3) effect of "flip" case, in which chemical species of the high-speed side and the low-speed side are exchanged. This study proves the capability of the fast mixing model for simulating reacting shear flows.

Flow on an airfoil was investigated with plasma synthetic jet actuator. Plasma synthetic jet actuator is a flow control device which is composed of electrodes with A.C. signal, using electrohydrodynamic effect and induces a flow around the electrodes. From the characteristics of electrical device, plasma synthetic jet actuator has some important advantages; for example, miniaturization, maintenance free, and easy to control. From these characteristics, it is effective to apply flow control around an airfoil with plasma synthetic jet actuator. In this study, the behavior of the plasma synthetic jet actuator around an airfoil is observed by experiment. A NACA0012 airfoil with plasma synthetic jet actuator is set in the wind tunnel. The wake velocity behind air foil is measured with and without the actuator. Experimental result with the Delayed Feedback Control for the flow control system is shown in this paper. The results show good improvement for the plasma synthetic jet actuator to reduce drag in the high angle of attacks.