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Multichannel Plasma Synthetic Jet Actuator Driven by Marx High-Voltage Generator

AIAA JOURNAL 2021年第9期59卷 3417-3430页

作者： Liu, Rubing Lin, Ruixin Lian, Guangce Xue, Shenghui Lin, Qi Xiamen Univ Sch Aerosp Engn Xiamen 361102 Peoples R China Xiamen Univ Fujian Key Lab Plasma & Magnet Resonance Res Xiamen 361102 Peoples R China

The plasma synthetic jet (PSJ) is a high-energy synthetic jet that is excited by gas spark discharging plasma in an active flow-control area. Because achieving large-scale flow-control applications is impossible with only one high-voltage power supply, a multichannel PSJ actuator (PSJA) driven by a four-stage Marx high-voltage generator (Marx-generator plasma synthetic jet [MPSJ]) was designed, and its basic discharge characteristics and jet performance were determined. In this study, discharge images were captured, discharge voltages and currents of five discharge channels were measured, and discharge frequencies were analyzed theoretically. Lastly, the jet performance of the multichannel actuators was studied at different discharge frequencies via high-speed schlieren imaging. The results show that the MPSJ can discharge in a synchronized manner to excite the multichannel PSJAs repeatedly. In the breakdown process, the discharge voltage can be multiplied by the MPSJ. The discharge frequency calculated via the theoretical model was near the measured value at low discharge frequencies. The jet intensity of the last-stage actuator was the strongest because its discharge voltage was the highest. The discharge frequency can affect the jet start time but has little negative effect on the jet front speed, which is beneficial for MPSJ applications in active flow control.

关键词： Plasma Actuator Marx Generator active flow control Hypersonic flows Capacitance Vortex Rings Power System Image Resolution Image Analysis Numerical Simulation

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Discrete Sweeping Jets as Tools for Improving the Performance of the V-22

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JOURNAL OF AIRCRAFT 2009年第6期46卷 2098-2106页

作者： Seele, Roman Tewes, Philipp Woszidlo, Rene McVeigh, Michael A. Lucas, Nathaniel J. Wygnanski, Israel J. Univ Arizona Dept Aerosp & Mech Engn Tucson AZ 85721 USA Boeing Co Philadelphia PA 19142 USA

Experiments aimed at delaying flow separation through discrete jets pointing in the direction of streaming and sweeping side to side along the span were conducted on a V-22 airfoil with and without deflected trailing-edge flaps. The results indicated substantial drag reduction and lift increase at moderately low inputs of mass and momentum. Additional experiments were carried out on a semispan V-22 wing/nacelle combination, and they too provided an increase in lift-to-drag ratio LID of approximately 60% (although active flow control was applied to the wing only). The effectiveness of lite sweeping jets on reducing the download force acting on at V-22 full-span powered model in hover was also examined. A 29% reduction in download was realized using the embedded sweeping jets, corresponding approximately to a 2000 Ib increase in hover lift.

关键词： Cambered Airfoil Vortex Generators Lift to Drag Ratio active flow control flow Separation Trailing Edge Flap Lift Coefficient Aeroplane Aspect Ratio Thrust Vectoring

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Impingement Cooling Performance Analysis and Improvement of Synthetic Jets for Electronic Devices

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2019年第3期33卷 856-864页

作者： Liu, Zhuo Yu, Qinghua Mei, Ziyue Xie, Danmei Wuhan Univ Key Lab Hydraul Machinery Transients Minist Educ Wuhan 430072 Hubei Peoples R China Wuhan Univ Sch Power & Mech Engn Wuhan 430072 Hubei Peoples R China

With the development of miniaturization, high power density, and a high degree of integration of electronic devices, heat dissipation has become a major factor constraining its development. As an active flow control technology, synthetic jets can significantly enhance heat transfer and cooling ability. In this paper, an unsteady numerical model of heat transfer is established to explore the impingement cooling performance of synthetic jets. The effect of nozzle-to-surface distance on the cooling performance is analyzed. The results show that the cooling ability of synthetic jets first increases and then decreases with an increasing nozzle-to-surface distance. At small nozzle-to-surface distances, there is a significant recirculation phenomenon of hot air, leading to a notable deterioration of heat transfer and cooling performance. To solve this issue at small nozzle-to-surface distances, a hybrid synthetic jet based on a fluid diode is designed. The further simulation results show that the proposed hybrid synthetic jet can effectively avoid recirculation of hot air and significantly improve the impingement cooling ability at small nozzle-to-surface distances. The temperature of the target surface under the action of the proposed hybrid synthetic jet is decreased by about 10 degrees C in comparison with the conventional synthetic jet without fluid diodes.

关键词： Heat Transfer Coefficients Numerical Modeling active flow control Heat Dissipation Vortices Numerical Simulation Natural Convection active Clearance control Laminar Boundary Layer Viscosity

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Effects of nozzle geometry and active blowing on lift enhancement for upper surface blowing configuration

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AEROSPACE SCIENCE AND TECHNOLOGY 2021年 111卷

作者： Xiao, Tianhang Zhu, Zhenhao Deng, Shuanghou Gui, Feng Li, Zhengzhou Zhou, Zheng Nanjing Univ Aeronaut & Astronaut Coll Aerosp Engn 29 Yudao St Nanjing 210016 Peoples R China AECC Sichuan Gas Turbine Estab Chengdu 610500 Peoples R China China Aerodynam Res & Dev Ctr Sci & Technol Scramjet Lab Mianyang 621000 Sichuan Peoples R China

Upper Surface Blowing (USB) has been regarded as a promising lift enhancement technique for short-take-off and landing (STOL) applications. The present study conducted numerical investigations to further explore the potential capability of USB technique by passive and active flow control strategies. Computations were accomplished by a Reynolds-averaged Navier-Stokes solver enclosed by the two equation k-omega shear stress transport turbulence model. The propulsion effect of the up-mounted engine was represented by the Turbine Powered Simulator (TPS). Results show that aerodynamic lift of using USB system is significantly enhanced due to the attenuation of plume edge roll-up vortex which is beneficial to the Coanda effect. Varying nozzle geometries can augment lift by alleviating the three-dimensional edge effect and thus delaying the rollup of plume with a thinner jet sheet. Compared to the passive flow control method by nozzle geometry modification, active constant blowing flow control technique shows a more promising potential for lift enhancement for USB powered system. Within the test cases, a 50% lift increment can be achieved by using constant blowing on the USB system. (C) 2021 Elsevier Masson SAS. All rights reserved.

关键词： Upper surface blowing Geometric change active flow control Lift enhancement

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Air Interactions of Magnetically Driven Plasma Discharges in Crossflow

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AIAA JOURNAL 2024年第2期62卷 530-541页

作者： Hristov, Georgi K. Ansell, Phillip J. Zimmerman, Joseph W. Carroll, David L. Univ Illinois Dept Aerosp Engn Urbana IL 61801 USA CU Aerosp Champaign IL 61822 USA

Motivated by the use of magnetohydrodynamic devices in fluid dynamic flow control research, the current work experimentally studied the actuation mechanism and the resulting aerodynamic interactions of magnetically driven low-current arc-plasma discharges. The investigation was conducted in the context of boundary-layer interactions in low-speed crossflow conditions through the use of coaxial and v-shaped geometries. Time-averaged velocity field measurements showed that the toroidal region of vorticity induced by the coaxial geometry in quiescent air resulted in the formation of a horseshoe vortex in crossflow. Similarly, the v-shaped actuator resulted in the formation of streamwise vortices. The resulting boundary layers had s-shaped streamwise velocity profiles as measured in the wall-normal direction characteristic for the flow downstream of a conventional vortex generator pair, due to the three-dimensional mixing induced by coherent vortex structures. A simplified model based on intermolecular momentum transfer through collisions is proposed to explain the fundamental discharge-air interactions and the induced flowfields. These results inform the applications of various magnetically driven discharges in the field of aerodynamic flow control.

关键词： Plasma Actuator Magnetohydrodynamic Devices Streamwise Velocity Freestream Conditions Arc plasma active flow control Vortex Generators Electrohydrodynamics Boundary Layer Separation

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Experimental and numerical investigation of an S-shaped duct using pulsed jet actuators with multiple angles

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THERMAL SCIENCE AND ENGINEERING PROGRESS 2023年 46卷

作者： Wang, Chengze Lu, Huawei Kong, Xiaozhi Wang, Shiqi Guo, Shuang Dalian Maritime Univ Sch Marine Engn Dalian 116026 Peoples R China Dalian Maritime Univ Sch Naval Architecture & Ocean Engn Dalian 116026 Peoples R China Aero Engine Acad China Adv Jet Prop Innovat Ctr Beijing 101304 Peoples R China Dalian Univ Technol Sch Energy & Power Engn Dalian 116024 Peoples R China

The complexity and twistiness of the ultra-compact S-shaped ducts with high curvature aggravate the internal flow separation, which affects the intake efficiency. An advanced flow control technology, pulsed jet actuators (PJAs), was implemented to improve the flow condition in the S-shaped duct at a Mach number of 0.4. Based on the considerable control effect obtained from the experimental studies, the influence of the pulsed jet angles on the S-shaped duct was further investigated by utilizing the unsteady Reynolds-averaged Navier-Stokes equations (URANS). The jet angles as a research parameter were set to 15 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees, respectively. Moreover, steady jet schemes were adopted to reveal the unsteady flow control mechanism of the pulsed jet. The results showed that the overall performance of the S-shaped duct with the pulsed jet was improved, mainly attributed to the additional kinetic energy and dispersion. The total pressure loss coefficient and distortion index at the aerodynamic interface plane (AIP) were decreased by 7 % and 2.9 % when the pulsed jet angle was 30 degrees. Furthermore, the temperature distortion was significantly improved, with a maximum temperature rise rate of -87.59 K/s. It is concluded that the suitable penetration of the mainstream is the prerequisite for achieving the best flow control effect.

关键词： active flow control S-shaped duct Pulsed jet actuators flow separation

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Effects of installation location of fluidic oscillators on aerodynamic performance of an airfoil

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AEROSPACE SCIENCE AND TECHNOLOGY 2020年 99卷

作者： Kim, Sang-Hyuk Kim, Kwang-Yong Inha Univ Dept Mech Engn Incheon 22212 South Korea

This study numerically investigates the effects of the installation location of fluidic oscillators on the aerodynamic performance of a NACA 0015 airfoil. The oscillators are embedded in the suction surface of the airfoil. An unsteady flow analysis was performed using three-dimensional Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model. The angle of attack was varied from 0 to 24 degrees, and four installation locations between the leading and trailing edges of the airfoil were used to analyze the lift and drag performance. The installation location with the highest lift coefficient depended on the angle of attack (and thus the location of flow separation), but greater drag reduction was obtained when the fluidic oscillators were installed closer to the leading edge regardless of the angle of attack. This location of the oscillators also produced the highest lift-to-drag ratio. (C) 2020 Elsevier Masson SAS. All rights reserved.

关键词： Fluidic oscillator NACA 0015 airfoil Installation location active flow control Unsteady Reynolds-averaged Navier-Stokes equations

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Development of a flexible dielectric-barrier-discharge plasma actuator fabricated by inkjet printing using silver nanoparticles-based ink

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SENSORS AND ACTUATORS A-PHYSICAL 2021年 330卷

作者： Sato, Shintaro Enokido, Tomoki Ashikawa, Kenichiro Matsubara, Masaki Kanie, Kiyoshi Ohnishi, Naofumi Tohoku Univ Dept Aerosp Engn Sendai Miyagi 9808579 Japan Tohoku Univ Inst Multidisciplinary Res Adv Mat Sendai Miyagi 9808577 Japan Natl Inst Technol Sendai Coll Natori Miyagi 9811239 Japan

We demonstrate that a flexible dielectric-barrier-discharge (DBD) plasma actuator fabricated by an inkjet printing process using metallic inks generates stable surface discharge and ionic wind for active airflow control. The establishment of a practical fabrication method for DBD plasma actuators is a critical issue to be tackled for industrial applications. The inkjet process requires just the printing of the metallic inks and sintering processes while the conventional photolithography technology requires a lot of processes for the fabrication of the DBD plasma actuators. The electrical and mechanical characteristics of a multistage DBD plasma actuator fabricated by this printed electronics technology are investigated and are compared with the DBD plasma actuator made by the conventional method using copper tape. The DBD plasma actuator developed in this study induces a similar or even stronger ionic wind than that of the conventional one. Also, a thin exposed electrode (<^>Y1 & micro;m), which is preferable in terms of airflow control applications, is achieved by the inkjet printing process. The development of the fabrication method using printed electronics expands the application field of the DBD plasma actuator, including complex curved surfaces and full-scale size applications. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Printed electronics Dielectric barrier discharge Plasma actuator active flow control Electrohydrodynamics

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flow Reattachment on a NACA 0025 Airfoil Using an Array of Microblowers

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AIAA JOURNAL 2023年第6期61卷 2476-2485页

作者： Xu, Kecheng Lavoie, Philippe Sullivan, Pierre Univ Toronto Inst Aerosp Studies Toronto ON M3H 5T6 Canada Univ Toronto Toronto ON M5S 3G8 Canada Univ Toronto Dept Mech & Ind Engn Toronto ON Canada

An array of commercially available synthetic jet actuators was developed for controlling flow separation on a NACA 0025 airfoil. The array is more compact in comparison to standard synthetic jet actuators previously studied for separation control. Wind tunnel experiments were conducted at chord Reynolds number Re-c=10(5) and alpha=10?degrees control of separation was applied by the array through forcing at the wake and shear layer frequencies (F+=1.18 and F+=11.76, respectively). Both effectively suppress flow separation, increase lift, and decrease drag. The dynamics of the reattached flow show different feature for the two forcing schemes. The results demonstrate that this array has comparable control effectiveness on separation to other synthetic jet actuators.

关键词： NACA 0015 Laminar Boundary Layer Freestream Velocity Piezoelectric Actuators Vortex Dynamics Aerodynamic Performance Kelvin Helmholtz Instability flow Characteristics active flow control flow Visualization

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Lift Enhancement of a Stationary Wing in a Wake

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AIAA JOURNAL 2020年第11期58卷 4613-4619页

作者： Zhang, Z. Wang, Z. Gursul, I. Univ Bath Dept Mech Engn Bath BA2 7AY Avon England

A stationary wing placed in the wake of a bluff body experiences lift enhancement. The quasi-periodic flow in the wake causes excitation of the separated flow in the poststall conditions. The increase in the time-averaged lift force is associated with the flow separation, leading-edge vortex formation, and subsequent reattachment in a process similar to the dynamic stall of oscillating wings. The lift enhancement is maximum for an optimal offset distance from the wake centerline. At the optimal location, potential flow oscillations, rather than the direct impingement of large vortices in the wake, provide the excitation. The smaller amplitude flow oscillations lead to a large separation bubble in the time-averaged sense in the poststall regime. The delayed flow separation in the wake has a similar mechanism and frequency to those of the active flow control methods for separation. The degree of the lift enhancement is remarkable, given that the wake at a Reynolds number of 50,000 is expected to be highly three-dimensional.

关键词： active flow control Karman Vortex Street Aircraft Wings Separated flows flow Separation Lift Coefficient Dynamic Pressure Particle Image Velocimetry Freestream Turbulence Probability Distribution

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