In wind tunnels, long cantilever sting support systems with low structural damping encounter flow separation and turbulence during wind tunnel tests, which results in destructive low-frequency and big-amplitude resona...In wind tunnels, long cantilever sting support systems with low structural damping encounter flow separation and turbulence during wind tunnel tests, which results in destructive low-frequency and big-amplitude resonance, leading to data quality degradation and test envelope limitation. To ensure planed test envelope and obtain high-quality data, an active damping vibration control system independent of balance signal based on stackable piezoelectric actuators and velocity feedback using accelerometer, is proposed to improve the support stability and wind tunnel testing safety in transonic wind tunnel. Meanwhile, a design of powerful sting-root embedded active damping device is given and an active vibration control method is presented based on the mechanism analysis of aircraft model vibration. Furthermore, a self-adaptive fuzzy Proportion Differentiation(PD) control model is proposed to realize control parameters adjustment automatically for various testing conditions. Besides, verification tests are performed in laboratory and a continuous transonic wind tunnel. Experimental results indicate that the aircraft model does not vibrate obviously from -4° to 11° at Ma = 0.6, the number of useable angle-of-attack has increased by 7° at Ma = 0.6 and 5° at Ma = 0.7 respectively, satisfying the requirements of practical wind tunnel tests.展开更多
Aircraft are inevitably affected by gust during flight,which disturbs the regular operations of pilots and worsens the ride quality.In more grievous cases,flight mission cannot be completed and the flight safety may b...Aircraft are inevitably affected by gust during flight,which disturbs the regular operations of pilots and worsens the ride quality.In more grievous cases,flight mission cannot be completed and the flight safety may be disserved.In order to improve the ride quality and the fatigue life of the plane structure under the affect of gust,it is necessary to explore and validate the gust alleviation schemes.Through the low-speed wind tunnel test,the gust alleviation active control technology applied to elastic aircraft is studied.For a large-type passenger plane configuration with high aspect ratio wing,a test system was designed and three gust alleviation control schemes with PID controllers were proposed.Finally the gust alleviation control low-speed wind tunnel test was carried out in the FD-09 wind tunnel.Test results showed that at certain speed and gust frequency,all of the 3 control schemes can alleviate the acceleration at fuselage and wing-tip to a certain extent,as well as the bending moment of wing-root.The gust alleviation control scheme,which uses aileron,elevator and canard as control surfaces synthetically,gives the most satisfying gust alleviation effect.展开更多
An active control technique utilizing piezoelectric actuators to alleviate gust-response loads of a large-aspect-ratio flexible wing is investigated. Piezoelectric materials have been extensively used for active vibra...An active control technique utilizing piezoelectric actuators to alleviate gust-response loads of a large-aspect-ratio flexible wing is investigated. Piezoelectric materials have been extensively used for active vibration control of engineering structures. In this paper, piezoelectric materials further attempt to suppress the vibration of the aeroelastic wing caused by gust. The motion equation of the flexible wing with piezoelectric patches is obtained by Hamilton＇s principle with the modal approach, and then numerical gust responses are analyzed, based on which a gust load alleviation（GLA） control system is proposed. The gust load alleviation system employs classic propor tional-integral-derivative（PID） controllers which treat piezoelectric patches as control actuators and acceleration as the feedback signal. By a numerical method, the control mechanism that piezoelectric actuators can be used to alleviate gust-response loads is also analyzed qualitatively. Furthermore, through low-speed wind tunnel tests, the effectiveness of the gust load alleviation active control technology is validated. The test results agree well with the numerical results. Test results show that at a certain frequency range, the control scheme can effectively alleviate the z and x wingtip accelerations and the root bending moment of the wing to a certain extent. The control system gives satisfying gust load alleviation efficacy with the reduction rate being generally over 20%.展开更多
Circulation Control(CC) realizes rudderless flight control by driving compressed air jet to generate a virtual rudder surface, which significantly improves low detectability. The layout plan of combined control rudder...Circulation Control(CC) realizes rudderless flight control by driving compressed air jet to generate a virtual rudder surface, which significantly improves low detectability. The layout plan of combined control rudder surface is proposed based on the tailless flying wing aircraft. The closed-loop jet actuator system and stepless rudder surface switching control strategy are used to quantitatively study the control characteristics of circulation actuator for pitch and roll attitude through 3-DOF virtual flight test in a wind tunnel with a powered model at wind speed of 40 m/s. The results show that the combined use of circulation actuators can achieve bidirectional continuous and stable control of the aircraft’s pitch and roll attitude, with the maximum pitch rate of 12.3(°)/s and the maximum roll rate of 21.5(°)/s;the response time of attitude angular rate varying with the jet pressure ratio is less than 0.02 s, which can satisfy the control response requirements of aircraft motion stability for the control system;the jet rudder surface has a strong moment control ability, and the pitch moment of the jet elevator with a pressure ratio of 1.28 is the same as that of the mechanical elevator with 28° rudder deflection, which can expand the flight control boundary.展开更多
Vibrations impose negative impacts on the effectiveness and public acceptance of helicopters.Active rotors with trailing-edge flaps have been proved to be an effective way to actively eliminate helicopter vibrations.F...Vibrations impose negative impacts on the effectiveness and public acceptance of helicopters.Active rotors with trailing-edge flaps have been proved to be an effective way to actively eliminate helicopter vibrations.For the existing control algorithm based on offline system identification,the transfer functions of an active rotor under different flight conditions are pre-requisites to implement closed-loop vibration control.In this study,a three-bladed active rotor with improved trailing-edge flaps is designed,and wind-tunnel tests are conducted to identify the transfer functions of this active rotor using frequency sweep and phase sweep methods.The experimental results demonstrate that these transfer functions are insensitive to the variation of flight speeds:the amplitude of the transfer function varies slightly,while the phase delay almost remains unchanged.In addition,this finding is validated through closed-loop vibration control tests with the active rotor.The transfer function obtained from the hover test results is also applicable to closed-loop vibration control tests under the forward flight conditions.This will dramatically simplify the implementation and operation of an active rotor.展开更多
The control law synthesis, wind tunnel test and engineering properties ofdigital active flutter suppression system (AFSS) are presented.A method ofdiscretization of continuous domain is adopted in the control law desi...The control law synthesis, wind tunnel test and engineering properties ofdigital active flutter suppression system (AFSS) are presented.A method ofdiscretization of continuous domain is adopted in the control law design, and four kindsof control laws are demonstrated during the wind tunnel test with this method. Thewind tunnel test affirms the correctness of the theoretical computation and the test de-sign. The control law is implemented by use of microcomputer and industry controllerin this test. The engineering properties of the active flutter suppression system are pres-ented. The research on a dynamically scaled wing/ store configuration shows that theflutter speed increases by 20% or so and the performance of the system is basically satis-factory.展开更多
基金co-supported by the National Natural Science Foundation of China (Nos. 51622501 and 51621064)the high-level personnel innovation support program of Dalian (No. 2017RJ04)
文摘In wind tunnels, long cantilever sting support systems with low structural damping encounter flow separation and turbulence during wind tunnel tests, which results in destructive low-frequency and big-amplitude resonance, leading to data quality degradation and test envelope limitation. To ensure planed test envelope and obtain high-quality data, an active damping vibration control system independent of balance signal based on stackable piezoelectric actuators and velocity feedback using accelerometer, is proposed to improve the support stability and wind tunnel testing safety in transonic wind tunnel. Meanwhile, a design of powerful sting-root embedded active damping device is given and an active vibration control method is presented based on the mechanism analysis of aircraft model vibration. Furthermore, a self-adaptive fuzzy Proportion Differentiation(PD) control model is proposed to realize control parameters adjustment automatically for various testing conditions. Besides, verification tests are performed in laboratory and a continuous transonic wind tunnel. Experimental results indicate that the aircraft model does not vibrate obviously from -4° to 11° at Ma = 0.6, the number of useable angle-of-attack has increased by 7° at Ma = 0.6 and 5° at Ma = 0.7 respectively, satisfying the requirements of practical wind tunnel tests.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91116005,10902006)
文摘Aircraft are inevitably affected by gust during flight,which disturbs the regular operations of pilots and worsens the ride quality.In more grievous cases,flight mission cannot be completed and the flight safety may be disserved.In order to improve the ride quality and the fatigue life of the plane structure under the affect of gust,it is necessary to explore and validate the gust alleviation schemes.Through the low-speed wind tunnel test,the gust alleviation active control technology applied to elastic aircraft is studied.For a large-type passenger plane configuration with high aspect ratio wing,a test system was designed and three gust alleviation control schemes with PID controllers were proposed.Finally the gust alleviation control low-speed wind tunnel test was carried out in the FD-09 wind tunnel.Test results showed that at certain speed and gust frequency,all of the 3 control schemes can alleviate the acceleration at fuselage and wing-tip to a certain extent,as well as the bending moment of wing-root.The gust alleviation control scheme,which uses aileron,elevator and canard as control surfaces synthetically,gives the most satisfying gust alleviation effect.
基金supported by the National Key Research and Development Program (2016YFB 0200703)
文摘An active control technique utilizing piezoelectric actuators to alleviate gust-response loads of a large-aspect-ratio flexible wing is investigated. Piezoelectric materials have been extensively used for active vibration control of engineering structures. In this paper, piezoelectric materials further attempt to suppress the vibration of the aeroelastic wing caused by gust. The motion equation of the flexible wing with piezoelectric patches is obtained by Hamilton＇s principle with the modal approach, and then numerical gust responses are analyzed, based on which a gust load alleviation（GLA） control system is proposed. The gust load alleviation system employs classic propor tional-integral-derivative（PID） controllers which treat piezoelectric patches as control actuators and acceleration as the feedback signal. By a numerical method, the control mechanism that piezoelectric actuators can be used to alleviate gust-response loads is also analyzed qualitatively. Furthermore, through low-speed wind tunnel tests, the effectiveness of the gust load alleviation active control technology is validated. The test results agree well with the numerical results. Test results show that at a certain frequency range, the control scheme can effectively alleviate the z and x wingtip accelerations and the root bending moment of the wing to a certain extent. The control system gives satisfying gust load alleviation efficacy with the reduction rate being generally over 20%.
基金supported by the Equipment Pre-research Common Technology Project,China(No.41406010101).
文摘Circulation Control(CC) realizes rudderless flight control by driving compressed air jet to generate a virtual rudder surface, which significantly improves low detectability. The layout plan of combined control rudder surface is proposed based on the tailless flying wing aircraft. The closed-loop jet actuator system and stepless rudder surface switching control strategy are used to quantitatively study the control characteristics of circulation actuator for pitch and roll attitude through 3-DOF virtual flight test in a wind tunnel with a powered model at wind speed of 40 m/s. The results show that the combined use of circulation actuators can achieve bidirectional continuous and stable control of the aircraft’s pitch and roll attitude, with the maximum pitch rate of 12.3(°)/s and the maximum roll rate of 21.5(°)/s;the response time of attitude angular rate varying with the jet pressure ratio is less than 0.02 s, which can satisfy the control response requirements of aircraft motion stability for the control system;the jet rudder surface has a strong moment control ability, and the pitch moment of the jet elevator with a pressure ratio of 1.28 is the same as that of the mechanical elevator with 28° rudder deflection, which can expand the flight control boundary.
基金co-supported by the National Natural Science Foundation of China(No.11402110)a project funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,China。
文摘Vibrations impose negative impacts on the effectiveness and public acceptance of helicopters.Active rotors with trailing-edge flaps have been proved to be an effective way to actively eliminate helicopter vibrations.For the existing control algorithm based on offline system identification,the transfer functions of an active rotor under different flight conditions are pre-requisites to implement closed-loop vibration control.In this study,a three-bladed active rotor with improved trailing-edge flaps is designed,and wind-tunnel tests are conducted to identify the transfer functions of this active rotor using frequency sweep and phase sweep methods.The experimental results demonstrate that these transfer functions are insensitive to the variation of flight speeds:the amplitude of the transfer function varies slightly,while the phase delay almost remains unchanged.In addition,this finding is validated through closed-loop vibration control tests with the active rotor.The transfer function obtained from the hover test results is also applicable to closed-loop vibration control tests under the forward flight conditions.This will dramatically simplify the implementation and operation of an active rotor.
文摘The control law synthesis, wind tunnel test and engineering properties ofdigital active flutter suppression system (AFSS) are presented.A method ofdiscretization of continuous domain is adopted in the control law design, and four kindsof control laws are demonstrated during the wind tunnel test with this method. Thewind tunnel test affirms the correctness of the theoretical computation and the test de-sign. The control law is implemented by use of microcomputer and industry controllerin this test. The engineering properties of the active flutter suppression system are pres-ented. The research on a dynamically scaled wing/ store configuration shows that theflutter speed increases by 20% or so and the performance of the system is basically satis-factory.
