Gouji Yamada

Jet Vectoring and Enhancement of Flow Control Performance of Trielectrode Plasma Actuator Utilizing Sliding Discharge

The flow control performance and jet vectoring characteristics of trielectrode (TED) plasma actuators on quiescent air were analyzed. To examine the body force generated from the actuator, the thrust of the induced jet was measured, as a reaction of the aerodynamic force from the actuator. The corresponding induced jet was visualized by means of highspeed Schrielen Visualization with the discharge conditions to understand physical phenomena on the actuator. The experiments show that the thrust generated by the TED actuator depended on the applied DC voltage. By applying high negative DC voltage, with the existence of sliding discharge channels between the two exposed electrodes, the induced flow becomes in the pronounced vertical jet. The overall thrust is greatly improved from SDBD actuator at these regimes. The efficiency of SDBD actuator also shows substantial improvement. These confirm that the TED actuator could improve both body force and their power efficiency at the same time.

Development of Trielectrode Plasma Actuator and Its Application to Delta Wing Vortex Control

The flow control performances of the trielectrode plasma actuators are examined. By the balance measurement the TED-DBD (positive DC voltage was applied to the additional electrode) actuator enhances the thrust as the DC voltage increase, and the maximum thrust for the TED-DBD reaches 270% of the one for the SDBD actuator in the same conditions. The TED-SD (negative DC voltage to the additional electrode) actuator generates strong negative thrust up to 400% of SDBD case. The TED-SD actuator generated recirculation bubble on the electrode. The recirculation area becomes expanded and diverts their direction upward and reversed as the DC voltage increases. For the delta wing vortex control, the TED-SD plasma actuator was found to be feasible to control the flows that include massive three dimensional separations. The change in the direction of the induced jet generates peculiar control performance of the flow. Nomenclature fac = frequency of the AC voltage T = Thrust generated by plasma actuator Vax = AC voltage applied to the DBD electrode of plasma actuator, peak-to-peak Vdc = DC voltage applied to the Third (DC) electrode of plasma actuator

Characteristics of Arc-Heated Plasma Flow for Martian Atmosphere

Characteristics of plasma flow in a 10.5kW arc-heated wind tunnel are investigated by spectroscopic measurement. The test gases are 100 % CO2 and 90 % CO2 - 10% N2 mixture which simulates the Martian atmosphere. In CO2 plasma, radiation of C2 Swan bands system is predominant and strong radiation of atomic oxygen is seen in the near-infrared light region. In CO2 - N2 plasma, radiation of CN violet band system is much stronger than those of C2 Swan band system and atomic oxygen. By using the multipoint spectroscopic system, spatial profiles of spectra are obtained with high accuracy. With approaching the stagnation point, radiation intensity increases caused by the formation of shock wave around the hemisphere model. Thickness of shock layer is estimated to be 3mm from the stagnation point. The rotational and vibrational temperatures of C2 and CN are estimated by the spectrum fitting method using the SPRADIAN 2 and spatial distribution of temperatures are obtained. For C2, the rotational temperature is higher than vibrational temperature ahead of shock wave. These temperatures are almost same in the shock layer. For CN, the rotational temperature is lower than vibrational temperature, showing the opposite tendency observed in C2. However, in the shock layer, rotational and vibrational temperatures are almost same.