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Application of active flow control Technique for Gust Load Alleviation

Chinese Journal of Aeronautics 2011年第4期24卷 410-416页

作者： XU Xiaoping ZHU Xiaoping ZHOU Zhou FAN Ruijun National Key Laboratory of Science and Technology on UAV Northwestern Polytechnical University Xi 'an 710072 China Research Institute of Unmanned Aerial Vehicle Northwestern Polytechnical University Xi 'an 710072 China

A new gust load alleviation technique is presented in this paper based on active flow control. Numerical studies are conducted to investigate the beneficial effects on the aerodynamic characteristics of the quasi ＂Global Hawk＂ airfoil using arrays of jets during the gust process. Based on unsteady Navier-Stokes equations, the grid-velocity method is introduced to simulate the gust influence, and dynamic response in vertical gust flow perturbation is investigated for the airfoil as well. An unsteady surface transpiration boundary condition is enforced over a user specified portion of the airfoil’s surface to emulate the time dependent velocity boundary conditions. Firstly, after applying this method to simulate typical NACA0006 airfoil gust response to a step change in the angle of attack, it shows that the indicial responses of the airfoil make good agreement with the exact theoretical values and the calculated values in references. Furthermore, gust response characteristic for the quasi ＂Global Hawk＂ airfoil is analyzed. Five kinds of flow control techniques are introduced as steady blowing, steady suction, unsteady blowing, unsteady suction and synthetic jets. The physical analysis of the influence on the effects of gust load alleviation is proposed to provide some guidelines for practice. Numerical results have indicated that active flow control technique,as a new technology of gust load alleviation, can affect and suppress the fluid disturbances caused by gust so as to achieve the purpose of gust load alleviation.

关键词： active flow control gust response gust alleviation numerical simulation aerodynamics unsteady flow airfoil

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Ferrofluid moving thin films for active flow control

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Chinese Journal of Aeronautics 2021年第5期34卷 115-119页

作者： Francisco J.ARIAS Department of Fluid Mechanics Polytechnic University of CataloniaESEIAATC/Colom 1108222 BarcelonaSpain

Ferrofluid moving thin films and their possible significance with regard to active flow control for lift and attack angle enhancement are *** this strategy,a very thin film of ferrofluid is strongly attached at the wall of the wing by a normal magnetic field from below and pumped tangentially along the *** a simplified physical model and from the available experimental data on moving walls,the expected lift enhancement and effect on the attack angle were *** research and design is required in order to explore the possibilities in the use of ferrofluid moving thin films.

关键词： active flow control Boundary layer separation Ferrofluid

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Learning active flow control strategies of a swept wing by intelligent wind tunnel

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Theoretical & Applied Mechanics Letters 2024年第5期14卷 386-394页

作者： Yusi Wu Tingwei Ji Xinyu Lv Changdong Zheng Zhixian Ye Fangfang Xie School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China Fair Friend Institute of Intelligent Manufacturing Hangzhou Vocational&Technical CollegeHangzhou 310018China

An intelligent wind tunnel using an active learning approach automates flow control experiments to discover the aerodynamic impact of sweeping jet on a swept wing. A Gaussian process regression model is established to study the jet actuator's performance at various attack and flap deflection angles. By selectively focusing on the most informative experiments, the proposed framework was able to predict 3721 wing conditions from just 55experiments, significantly reducing the number of experiments required and leading to faster and cost-effective predictions. The results show that the angle of attack and flap deflection angle are coupled to affect the effectiveness of the sweeping jet. Meanwhile, increasing the jet momentum coefficient can contribute to lift enhancement;a momentum coefficient of 3% can increase the lift coefficient by at most 0.28. Additionally, the improvement effects are more pronounced when actuators are placed closer to the wing root.

关键词： active flow control Sweeping jet active learning Gaussian process regression

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Nacelle intake flow separation reduction at cruise condition using active flow control

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Propulsion and Power Research 2022年第3期11卷 337-352页

作者： Vinayak Ramachandran Nambiar Vassilios Pachidis Centre for Propulsion Engineering Cranfield UniversityBedfordMK430ALUK

Turbofan engine intakes are designed to provide separation-free flow at the fan faceover a wide range of operating conditions. But at some off-design conditions, like at high flightspeeds and high angles of attack (AoA), the aero engine intake may encounter flow *** boundary layer separation inside the nacelle inlet of an aircraft engine can lead to a largenumber of undesirable outcomes like reduction in fan efficiency, engine stall and high levels ofstress on the fan blades. active flow control is a promising solution to reduce inlet boundarylayer separation and the associated fan-face flow distortion at such off-design conditions. Byblowing pressurized air into the intake near the separation point, the boundary layer is ener-gized and separation can be controlled. This study investigates the applicability of lip blowing,an active flow control technique, to control intake separation and flow distortion at the ***, intake separation was triggered in a 3D CFD model based on the NASA CommonResearch Model (CRM) using high AoA cases at cruise condition (Mach number 0.85, Massflow capture ratio w0.7) and the features of separated flow were analyzed. Thereafter, activeflow control was introduce to the intake in the form of two types of lip blowing, direct andpitched blowing. The efficacy of lip blowing at achieving separation control in an ultra highbypass ratio turbofan engine intake has been established through this study. The present paperalso examines the significance of blowing parameters like the type of blowing, blowing pres-sure ratio, and blowing slot dimension, at different angles of attack to identify the critical con-trol parameters. Our research successfully establishes proof of concept by demonstrating the feasibility of using lip blowing for separation control in aero-intakes, via numerical ***, this study also provides crucial insights regarding the important variables to beconsidered for future experimental studies

关键词： Ultra high bypass ratio turbofan engine NASA Common Research Model Reynolds-averaged Navier-Stokes(RANS) Computational fluid dynamics(CFD) ANSYS Fluent Intake flow separation active flow control Lip blowing

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Review of actuators for high speed active flow control

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Science China(Technological Sciences) 2012年第10期55卷 2225-2240页

作者： WANG Lin LUO ZhenBing XIA ZhiXun LIU Bing DENG Xiong Science and Technology on Scrarnjet Laboratory National University of Defense TechnologyChangsha 410073China

Actuators are one of the key points for the development of active flow control *** methods of high speed flow control can provide enhanced propulsive efficiency and at the same time enable safe and maneuverable high speed *** development of high speed flight technology promotes the emergence of novel and robust *** review introduces the state of the art in the development of actuators that can be used in high speed active flow *** classification and different operation criteria of the actuators are *** specifications,mechanisms and applications of various popular actuator types including fluidic,mechanical,and plasma actuators are *** on the realistic need of high speed flow control and the existing results of actuators,a new actuator design method is *** last,the merits and drawbacks of the actuators are summarized and some suggestions on the development of active flow control technology are put forward.

关键词： active flow control actuators figure of merit fluidic mechanical plasma

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Advanced flow measurement and active flow control of aircraft with MEMS

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Engineering Sciences 2012年第5期10卷 26-32页

作者： Jiang Chengyu Deng Jinjun Ma Binghe Yuan Weizheng Key Laboratory of MicroYNano Systems for Aerospace Ministry of EducationNorthwestern Polytechnical UniversityXi'an 710072China

Advanced flow measurement and active flow control need the development of new type devices and ***-electro-mechanical systems(MEMS) technologies become the important and feasible approach for micro transducers *** paper introduces research works of MEMS/NEMS Lab in flow measurement sensors and active flow control *** sensors include the flexible thermal sensor array,capacitive shear stress sensor and high sensitivity pressure *** actuators are the balloon actuator and synthetic jet actuator *** wind tunnel test,these micro transducers achieve the goals of shear stress and pressure distribution measurement,boundary layer separation control,lift enhancement,*** unmanned aerial vehicle(UAV) flight test verifies the ability of maneuver control of micro *** the future work,micro sensor and actuator can be combined into a closed-loop control system to construct aerodynamic smart skin system for aircraft.

关键词： MEMS flow measurement active flow control smart skin

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NUMERICAL SIMULATION INVESTIGATION ON PARAMETERS INFLUENCING SYNTHETIC-JET FOR active flow control

NUMERICAL SIMULATION INVESTIGATION ON PARAMETERS INFLUENCING...

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2012全国压电和声波理论及器件技术研讨会

作者： Dang-guo YANG Jun LIU Yi ZHANG Jin-min LIANG Yao-hua LI State Key Laboratory of Aerodynamics China Aerodynamics Research and Development Center High Speed Aerodynamics Research Institute China Aerodynamics Research and Development Center School of Aerospace Tsinghua University

Synthetic-Jet（SJ） technology is a novel method for flow control in aerodynamic design of *** development of science and technology,flow control method based on SJ technology makes significant progress,and it is very ***,Synthetic-Jet actuator（SJA） has advantages of light weight,simple structure,no need for external air *** incessant requirements for high performances of spacecrafts,the application of active flow control technology,especially SJ technology,turns into one of the hottest research *** this paper,based on two-dimensional structured moving grids algorithm and multi-block grid technology,numerical simulation investigation about the effects of parameters on the performances of SJA is *** research results indicate that the maximum jet velocity increases as the SJA vibration frequency and amplitude increase,and decreases as the orifice diameter *** orifice thickness has little influence on the maximum jet *** flow presents turbulent characteristics at high Reynolds number（Re）,and the increase of Re makes diameter of vortex core and attenuation speed greater,the increase of Strouhal number（St） makes diameter of vortex core *** a word,the paper presents effects of different physical parameters,such as operating parameters,orifice parameters,Re,St,and so on,on flow characteristics of *** results may provide technical support for the design and application of SJA.

关键词： Synthetic-Jet active flow control Structured moving grids Parameters Numerical simulation

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Turbine Blade Boundary Layer Separation Suppression via Synthetic Jet: an Experimental and Numerical Study

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Journal of Thermal Science 2012年第5期21卷 404-412页

作者： Bernardini C. Carnevale M. Manna M. Martelli F. Simoni D. Zunino P. Università degli Studi di Firenze Firenze Italy Università degli Studi di Napoli Federico Ⅱ Napoli Italy Università degli Studi di Firenze FirenzeItaly Università degli Studi di Genova Genova Italy

The present paper focuses on the analysis of a synthetic jet device (with a zero net massflow rate) on a separated boundary layer. Separation has been obtained on a flat plate installed within a converging-diverging test section specifically designed to attain a local velocity distribution typical of a high-lift LPT blade. Both experimental and numerical investigations have been carried out. Unsteady RANS results have been compared with experiments in terms of time-averaged velocity and turbulence intensity distributions. Two different Reynolds number cases have been investigated, namely Re = 200,000 and Re = 70,000, which characterize low-pressure turbine operating conditions during take-off/landing and cruise. A range of synthetic jet aerodynamic parameters (Strouhal number and blowing ratio) has been tested in order to analyze the features of control-separated boundary layer interaction for the aforementioned Reynolds numbers.

关键词： Synthetic Jet Separated flow active flow control Unsteady flow Ultra High Lift LPT.

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Microjet flow control in an ultra-compact serpentine inlet

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Chinese Journal of Aeronautics 2015年第5期28卷 1381-1390页

作者： Da Xingya Fan Zhaolin Fan Jianchao Zeng Liquan Rui Wei Zhou Run State Key Laboratory of Aerodynamics China Aerodynamics Research and Development Center High Speed Aerodynamics Institute China Aerodynamics Research and Development Center China Aerodynamics Research and Development Center

Microjets are used to control the internal flow to improve the performance of an ultra-compact serpentine inlet. A highly offset serpentine inlet with length-to-diameter ratio of 2.5 is designed and static tests are conducted to analyze the internal flow characteristics in terms of pressure recovery, distortion and flow separation. flow separation is encountered in the second S-turn, and two strong counter-rotating vortices are formed at the aerodynamic interthce plane （AIP） face which occupy a quarter of the outlet area and result in severe pressure loss and distortion. A flow control model employing a row of microjets in the second turn is designed based on the internal flow characteristics and simplified CFD simulations. flow control tests are conducted to verify the control effectiveness and understand the characteristics as a function of inlet throat Mach number, injection mass flow ratio, jet Mach number and momentum coefficient. At all test Mach numbers, microjet flow control （MFC） effectively improves the recovery and reduces the distortion intensity. Between inlet throat Mach number 0.2 and 0.5, the strong flow separation in the second S-turn is suppressed at an optimum jet flow ratio of less than 0.65%, resulting in a maximum improvement of 4% for pressure recovery coefficient and a maximum decrease of 75% for circumferential distortion intensity at cruise. However, in order to suppress the flow separation, the injection rate should retain in an effective range. When the injection rate is higher than this range, the flow is degraded and the distortion contour is changed from 90° circumferential distortion pattern to 180° circumferential distortion pattern. Detailed data analysis shows that this optimum flow ratio depends on inlet throat Mach number and the monlcntunl coefficient affects the control effectiveness in a dual stepping manner.

关键词： active flow control Distortion intensity:Micro jet Pressure recovery Serpentine inlet

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Numerical Study of Dual Sweeping Jet Actuators for Corner Separation control in Compressor Cascade

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Journal of Thermal Science 2021年第1期30卷 201-209页

作者： MENG Qinghe DU Xin CHEN Shaowen WANG Songtao School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Unsteady behaviors are important issues in flow control of *** excitation or suction is widely investigated in compressor *** paper presents a discussion on the unsteady flow control realized by dual sweeping jet actuator(SJA)located on the blade suction *** unsteady numerical simulations were utilized to study the effect of applying dual SJAs on controlling the corner *** the numerical results,the following conclusions could be drawn with current compressor cascade.A maximum total pressure loss coefficient reduction of 6.8%was *** analysis of the flow field pointed out that the regulation mechanisms of the corner separation were different with each *** SJA ahead achieved an interruption of the suction side boundary layer development and the rear SJA enhanced the interaction and entrainment between the excitation stream and the secondary ***,the different unsteadiness structures of the flow field frequency spectrum compared with single SJA cases were *** first peak frequency corresponded to the difference of the two SJAs and the rest frequencies could be regulated to a base frequency and its harmonic frequencies.

关键词： sweeping jet actuator compressor cascade active flow control corner separation

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