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Youssef Mebarki - One of the best experts on this subject based on the ideXlab platform.
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A new hybrid control methodology for a morphing aircraft Wing-Tip actuation mechanism
Aeronautical Journal, 2019Co-Authors: Michel Joël Tchatchueng Kammegne, Mahmood Mamou, Lucian Teodor Grigorie, Ruxandra Botez, Youssef MebarkiAbstract:The focus of this paper is on the modelling of miniature electromechanical actuators used in a morphing Wing application, on the development of a control concept for these actuators, and on the experimental validation of the designed control system integrated in the morphing Wing-Tip model for a real aircraft. The assembled actuator includes as its main component a brushless direct current motor coupled to a trapezoidal screw by using a gearing system. A Linear Variable Differential Transformer (LVDT) is attached on each actuator giving back the actuator position in millimetres for the control system, while an encoder placed inside the motor provides the position of the motor shaft. Two actuation lines, each with two actuators, are integrated inside the Wing model to change its shape. For the experimental model, a full-scaled portion of an aircraft Wing Tip is used with the chord length of 1.5 meters and equipped on the upper surface with a flexible skin made of composite fibre materials. A controllable voltage provided by a power amplifier is used to drive the actuator system. In this way, three control loops are designed and implemented, one to control the torque and the other two to control the position in a parallel architecture. The parallel position control loops use feedback signals from different sources. For the first position control loop, the feedback signal is provided by the integrated encoder, while for the second one, the feedback signal comes from the LVDT. For the experimental model, the parameters for the torque control, but also for the position control-based encoder signal, are implemented in the power amplifier energising the electrical motor. On the other hand, a National Instruments real-time system is used to implement and test the position control-based LVDT signal. The experimental validation of the developed control system is realised in two independent steps: bench testing with no airflow and wind-tunnel testing. The pressure data provided by a number of Kulite sensors equipping the flexible skin upper surface and the infrared thermography camera visualisations are used to estimate the laminar-to-turbulent transition point position.
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optimization and design of an aircraft s morphing Wing Tip demonstrator for drag reduction at low speed part i aerodynamic optimization using genetic bee colony and gradient descent algorithms
Chinese Journal of Aeronautics, 2017Co-Authors: Andreea Koreanschi, Mahmood Mamou, Oliviu Sugar Gabor, Joran Acotto, Guillaume Brianchon, Gregoire Portier, Ruxandra Botez, Youssef MebarkiAbstract:In this paper, an ‘in-house’ genetic algorithm is described and applied to an optimization problem for improving the aerodynamic performances of an aircraft Wing Tip through upper surface morphing. The algorithm’s performances were studied from the convergence point of view, in accordance with design conditions. The algorithm was compared to two other optimization methods, namely the artificial bee colony and a gradient method, for two optimization objectives, and the results of the optimizations with each of the three methods were plotted on response surfaces obtained with the Monte Carlo method, to show that they were situated in the global optimum region. The optimization results for 16 wind tunnel test cases and 2 objective functions were presented. The 16 cases used for the optimizations were included in the experimental test plan for the morphing Wing-Tip demonstrator, and the results obtained using the displacements given by the optimizations were evaluated.
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optimization and design of an aircraft s morphing Wing Tip demonstrator for drag reduction at low speeds part ii experimental validation using infra red transition measurement from wind tunnel tests
Chinese Journal of Aeronautics, 2017Co-Authors: Andreea Koreanschi, Mahmood Mamou, Oliviu Sugar Gabor, Joran Acotto, Guillaume Brianchon, Gregoire Portier, Youssef MebarkiAbstract:In the present paper, an ‘in-house’ genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircraft Wing Tip through upper surface morphing. The optimization was performed for 16 flight cases expressed in terms of various combinations of speeds, angles of attack and aileron deflections. The displacements resulted from the optimization were used during the wind tunnel tests of the Wing Tip demonstrator for the actuators control to change the upper surface shape of the Wing. The results of the optimization of the flow behavior for the airfoil morphing upper-surface problem were validated with wind tunnel experimental transition results obtained with infra-red Thermography on the Wing-Tip demonstrator. The validation proved that the 2D numerical optimization using the ‘in-house’ genetic algorithm was an appropriate tool in improving various aspects of a Wing’s aerodynamic performances.
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Morphing Wing-Tip open loop controller and its validation during wind tunnel tests at the IAR-NRC
2016Co-Authors: Mohamed Sadok Guezguez, Mahmood Mamou, Youssef MebarkiAbstract:In this project, a Wing Tip of a real aircraft was designed and manufactured. This Wing Tip was composed of a Wing and an aileron. The Wing was equipped with a composite skin on its upper surface. This skin changed its shape (morphed) by use of 4 electrical in-house developed actuators and 32 pressure sensors. These pressure sensors measure the pressures, and further the loads on the Wing upper surface. Thus, the upper surface of the Wing was morphed using these actuators with the aim to improve the aerodynamic performances of the Wing-Tip. Two types of ailerons were designed and manufactured: one aileron is rigid (non-morphed) and one morphing aileron. This morphing aileron can change its shape also for the aerodynamic performances improvement. The morphing Wing-Tip internal structure is designed and manufactured, and is presented firstly in the paper. Then, the modern communication and control hardware are presented for the entire morphing Wing Tip equipped with actuators and sensors having the aim to morph the Wing. The calibration procedure of the Wing Tip is further presented, followed by the open loop controller results obtained during wind tunnel tests. Various methodologies of open loop control are presented in this paper, and results obtained were obtained and validated experimentally through wind tunnel tests.Peer reviewed: YesNRC publication: Ye
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Morphing Wing-Tip Open Loop Controller and its Validation During Wind Tunnel Tests at the IAR-NRC
National Institute for Aerospace Research “Elie Carafoli” - INCAS, 2016Co-Authors: Mohamed Sadok Guezguez, Mahmood Mamou, Youssef MebarkiAbstract:In this project, a Wing Tip of a real aircraft was designed and manufactured. This Wing Tip was composed of a Wing and an aileron. The Wing was equipped with a composite skin on its upper surface. This skin changed its shape (morphed) by use of 4 electrical in-house developed actuators and 32 pressure sensors. These pressure sensors measure the pressures, and further the loads on the Wing upper surface. Thus, the upper surface of the Wing was morphed using these actuators with the aim to improve the aerodynamic performances of the Wing-Tip. Two types of ailerons were designed and manufactured: one aileron is rigid (non-morphed) and one morphing aileron. This morphing aileron can change its shape also for the aerodynamic performances improvement. The morphing Wing-Tip internal structure is designed and manufactured, and is presented firstly in the paper. Then, the modern communication and control hardware are presented for the entire morphing Wing Tip equipped with actuators and sensors having the aim to morph the Wing. The calibration procedure of the Wing Tip is further presented, followed by the open loop controller results obtained during wind tunnel tests. Various methodologies of open loop control are presented in this paper, and results obtained were obtained and validated experimentally through wind tunnel tests
V A Tucker - One of the best experts on this subject based on the ideXlab platform.
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drag reduction by Wing Tip slots in a gliding harris hawk parabuteo unicinctus
The Journal of Experimental Biology, 1995Co-Authors: V A TuckerAbstract:The anterior-most primary feathers of many birds that soar over land bend upwards and separate vertically to form slotted Wing Tips during flight. The slots are thought to reduce aerodynamic drag, although drag reduction has never been demonstrated in living birds. Wing theory explains how the feathers that form the Tip slots can reduce induced drag by spreading vorticity horizontally along the Wing and by acting as Winglets, which are used on aircraft to make Wings non-planar and to spread vorticity vertically. This study uses the induced drag factor to measure the induced drag of a Wing relative to that of a standard planar Wing with the same span, lift and speed. An induced drag factor of less than 1 indicates that the Wing is non-planar. The minimum drag of a Harris' hawk gliding freely in a wind tunnel was measured before and after removing the slots by clipping the Tip feathers. The unclipped hawk had 7090 % of the drag of the clipped hawk at speeds between 7.3 and 15.0 m s-1. At a Wing span of 0.8 m, the unclipped hawk had a mean induced drag factor of 0.56, compared with the value of 1.10 assumed for the clipped hawk. A Monte Carlo simulation of error propagation and a sensitivity analysis to possible errors in measured and assumed values showed that the true mean value of the induced drag factor for the unclipped hawk was unlikely to be more than 0.93. These results for a living bird support the conclusions from a previous study of a feathered Tip on a model Wing in a wind tunnel: the feathers that form the slotted Tips reduce induced drag by acting as Winglets that make the Wings non-planar and spread vorticity both horizontally and vertically.
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gliding birds reduction of induced drag by Wing Tip slots between the primary feathers
The Journal of Experimental Biology, 1993Co-Authors: V A TuckerAbstract:1. The feathers at the Wing Tips of most birds that soar over land separate both horizontally and vertically in flight to form slotted Tips. The individual feathers in the slotted Tips resemble the Winglets used on the Wing Tips of some aircraft to reduce induced drag. 2. A Wing that produces lift leaves a pair of vortex sheets in its wake. Wing theory shows that Winglets can reduce the kinetic energy left in the vortex sheets, and hence the induced drag, by spreading vorticity both horizontally and vertically. 3. This paper describes the aerodynamic forces on a Wing made of a base Wing and different Wing Tips. The feathered Wing Tip was slotted and was made of four primary feathers from a Harris9 hawk (Parabuteo unicinctus). The Clark Y Tip was unslotted and was made of balsa wood shaped to a Clark Y aerofoil. The balsa feather Tip was slotted and was made of three balsa wood Wings shaped like feathers. 4. The base Wing in a wind tunnel at an air speed of 12.6 m s-1 generated upwash angles as high as 15° at the end of the Wing when the angle of attack of the Wing was 10.5°. The feathered Tip responded to upwash by increasing its lift to drag ratio (L/D) by 107 %, from 4.9 to 10.1, as the angle of attack of the base Wing increased from 4° to 14°. The L/D values of the balsa feather Tip and the Clark Y Tip increased by 49 % and 5 %, respectively, for the same change in angle of attack. 5. With the angle of attack of the base Wing fixed at 13°, changing the angle of attack of the Wing Tip changed the drag of the base Wing. The drag of the base Wing increased by 25 % as the angle of attack of the Clark Y Tip increased from 0° to 15°. The base Wing drag decreased by 6 % for the same change in the angle of attack of the feathered Tip. 6. The total drag of the Wing with the feathered Tip was 12 % less than that of a hypothetical Wing with the same lift and span, but with Tip feathers that did not respond to upwash at the end of the base Wing. This value is consistent with Wing theory predictions on drag reduction from Winglets. 7. Wings with the Tip and the base Wing locked together had lift and drag that increased with increasing base Wing angle of attack, as expected for conventional Wings. Span factors were calculated from these data - a large span factor indicates that a Wing has low induced drag for a given lift and Wing span. The Wing with the Clark Y Tip had a span factor that decreased from 1 to 0.75 as the angle of attack of the base Wing increased. Over the same range of angle of attack, the span factor of the Wing with the feathered Tip remained constant at 0.87. As the angle of attack of this Wing increased, aerodynamic forces spread the feathers vertically to form slots. With fully formed slots, the Wing had a higher span factor than the Wing with the unslotted Clark Y Tip. 8. Flow visualization with helium-filled bubbles showed that the addition of two Winglets to the Tip of a model Wing spread vorticity both horizontally and vertically in the wake of the Tip. 9. These observations taken together provide strong evidence that the Tip slots of soaring birds reduce induced drag in the sense that the separated Tip feathers act as Winglets and increase the span factor of the Wings.
Thomas P Ratvasky - One of the best experts on this subject based on the ideXlab platform.
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ice accretion formations on a naca 0012 swept Wing Tip in natural icing conditions
40th AIAA Aerospace Sciences Meeting & Exhibit, 2002Co-Authors: Mario Vargas, Julius Giriunas, Thomas P RatvaskyAbstract:An experiment was conducted in the DeHavilland DHC-6 Twin Otter Icing Research Aircraft at NASA Glenn Research Center to study the formation of ice accretions on swept Wings in natural icing conditions. The experiment was designed to obtain ice accretion data to help determine if the mechanisms of ice accretion formation observed in the Icing Research Tunnel are present in natural icing conditions. The experiment in the Twin Otter was conducted using a NACA 0012 swept Wing Tip. The model enabled data acquisition at 0 deg, 15 deg, 25 deg, 30 deg, and 45 deg sweep angles. Casting data, ice shape tracings, and close-up photographic data were obtained. The results showed that the mechanisms of ice accretion formation observed in-flight agree well with the ones observed in the Icing Research Tunnel. Observations on the end cap of the airfoil showed the same strong effect of the local sweep angle on the formation of scallops as observed in the tunnel.
Omar Khan - One of the best experts on this subject based on the ideXlab platform.
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Computed Effect of Wing Tip Configuration on Wing Load Characteristics of a High Speed Aircraft
53rd AIAA Aerospace Sciences Meeting, 2015Co-Authors: Jehanzeb Masud, Omar KhanAbstract:The Wing Tip configuration of an aircraft is important structurally and aerodynamically. The formation of Wing Tip vortices not only add to the induced drag but also decrease the lift produced by the Wing. This aspect becomes significantly important for high speed aircraft that have low aspect ratio Wings. In this paper effect of Wing Tip configurations of a high speed aircraft equipped with WingTip missile on its Wing load characteristics is presented. Normal force coefficient has been computed for the Wing panel of the aircraft for both with and without WingTip missile in transonic fight regime and a wide range of angle of attack. It is observed that the Wing Tip missile considerably alters the strength and structure of the WingTip vortices. It has also observed that as much as 20% increase in normal force coefficient occurs when the WingTip missile is mounted. This difference between the Wing loads of clean Wing and missile mounted Wing diminishes as the angle of attack is increased, this is due the shifting low pressure region on the Wing upper surface from Wing Tip towards Wing root as the root strake becomes effective.
Mahmood Mamou - One of the best experts on this subject based on the ideXlab platform.
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A new hybrid control methodology for a morphing aircraft Wing-Tip actuation mechanism
Aeronautical Journal, 2019Co-Authors: Michel Joël Tchatchueng Kammegne, Mahmood Mamou, Lucian Teodor Grigorie, Ruxandra Botez, Youssef MebarkiAbstract:The focus of this paper is on the modelling of miniature electromechanical actuators used in a morphing Wing application, on the development of a control concept for these actuators, and on the experimental validation of the designed control system integrated in the morphing Wing-Tip model for a real aircraft. The assembled actuator includes as its main component a brushless direct current motor coupled to a trapezoidal screw by using a gearing system. A Linear Variable Differential Transformer (LVDT) is attached on each actuator giving back the actuator position in millimetres for the control system, while an encoder placed inside the motor provides the position of the motor shaft. Two actuation lines, each with two actuators, are integrated inside the Wing model to change its shape. For the experimental model, a full-scaled portion of an aircraft Wing Tip is used with the chord length of 1.5 meters and equipped on the upper surface with a flexible skin made of composite fibre materials. A controllable voltage provided by a power amplifier is used to drive the actuator system. In this way, three control loops are designed and implemented, one to control the torque and the other two to control the position in a parallel architecture. The parallel position control loops use feedback signals from different sources. For the first position control loop, the feedback signal is provided by the integrated encoder, while for the second one, the feedback signal comes from the LVDT. For the experimental model, the parameters for the torque control, but also for the position control-based encoder signal, are implemented in the power amplifier energising the electrical motor. On the other hand, a National Instruments real-time system is used to implement and test the position control-based LVDT signal. The experimental validation of the developed control system is realised in two independent steps: bench testing with no airflow and wind-tunnel testing. The pressure data provided by a number of Kulite sensors equipping the flexible skin upper surface and the infrared thermography camera visualisations are used to estimate the laminar-to-turbulent transition point position.
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optimization and design of an aircraft s morphing Wing Tip demonstrator for drag reduction at low speed part i aerodynamic optimization using genetic bee colony and gradient descent algorithms
Chinese Journal of Aeronautics, 2017Co-Authors: Andreea Koreanschi, Mahmood Mamou, Oliviu Sugar Gabor, Joran Acotto, Guillaume Brianchon, Gregoire Portier, Ruxandra Botez, Youssef MebarkiAbstract:In this paper, an ‘in-house’ genetic algorithm is described and applied to an optimization problem for improving the aerodynamic performances of an aircraft Wing Tip through upper surface morphing. The algorithm’s performances were studied from the convergence point of view, in accordance with design conditions. The algorithm was compared to two other optimization methods, namely the artificial bee colony and a gradient method, for two optimization objectives, and the results of the optimizations with each of the three methods were plotted on response surfaces obtained with the Monte Carlo method, to show that they were situated in the global optimum region. The optimization results for 16 wind tunnel test cases and 2 objective functions were presented. The 16 cases used for the optimizations were included in the experimental test plan for the morphing Wing-Tip demonstrator, and the results obtained using the displacements given by the optimizations were evaluated.
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optimization and design of an aircraft s morphing Wing Tip demonstrator for drag reduction at low speeds part ii experimental validation using infra red transition measurement from wind tunnel tests
Chinese Journal of Aeronautics, 2017Co-Authors: Andreea Koreanschi, Mahmood Mamou, Oliviu Sugar Gabor, Joran Acotto, Guillaume Brianchon, Gregoire Portier, Youssef MebarkiAbstract:In the present paper, an ‘in-house’ genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircraft Wing Tip through upper surface morphing. The optimization was performed for 16 flight cases expressed in terms of various combinations of speeds, angles of attack and aileron deflections. The displacements resulted from the optimization were used during the wind tunnel tests of the Wing Tip demonstrator for the actuators control to change the upper surface shape of the Wing. The results of the optimization of the flow behavior for the airfoil morphing upper-surface problem were validated with wind tunnel experimental transition results obtained with infra-red Thermography on the Wing-Tip demonstrator. The validation proved that the 2D numerical optimization using the ‘in-house’ genetic algorithm was an appropriate tool in improving various aspects of a Wing’s aerodynamic performances.
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Morphing Wing-Tip open loop controller and its validation during wind tunnel tests at the IAR-NRC
2016Co-Authors: Mohamed Sadok Guezguez, Mahmood Mamou, Youssef MebarkiAbstract:In this project, a Wing Tip of a real aircraft was designed and manufactured. This Wing Tip was composed of a Wing and an aileron. The Wing was equipped with a composite skin on its upper surface. This skin changed its shape (morphed) by use of 4 electrical in-house developed actuators and 32 pressure sensors. These pressure sensors measure the pressures, and further the loads on the Wing upper surface. Thus, the upper surface of the Wing was morphed using these actuators with the aim to improve the aerodynamic performances of the Wing-Tip. Two types of ailerons were designed and manufactured: one aileron is rigid (non-morphed) and one morphing aileron. This morphing aileron can change its shape also for the aerodynamic performances improvement. The morphing Wing-Tip internal structure is designed and manufactured, and is presented firstly in the paper. Then, the modern communication and control hardware are presented for the entire morphing Wing Tip equipped with actuators and sensors having the aim to morph the Wing. The calibration procedure of the Wing Tip is further presented, followed by the open loop controller results obtained during wind tunnel tests. Various methodologies of open loop control are presented in this paper, and results obtained were obtained and validated experimentally through wind tunnel tests.Peer reviewed: YesNRC publication: Ye
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Morphing Wing-Tip Open Loop Controller and its Validation During Wind Tunnel Tests at the IAR-NRC
National Institute for Aerospace Research “Elie Carafoli” - INCAS, 2016Co-Authors: Mohamed Sadok Guezguez, Mahmood Mamou, Youssef MebarkiAbstract:In this project, a Wing Tip of a real aircraft was designed and manufactured. This Wing Tip was composed of a Wing and an aileron. The Wing was equipped with a composite skin on its upper surface. This skin changed its shape (morphed) by use of 4 electrical in-house developed actuators and 32 pressure sensors. These pressure sensors measure the pressures, and further the loads on the Wing upper surface. Thus, the upper surface of the Wing was morphed using these actuators with the aim to improve the aerodynamic performances of the Wing-Tip. Two types of ailerons were designed and manufactured: one aileron is rigid (non-morphed) and one morphing aileron. This morphing aileron can change its shape also for the aerodynamic performances improvement. The morphing Wing-Tip internal structure is designed and manufactured, and is presented firstly in the paper. Then, the modern communication and control hardware are presented for the entire morphing Wing Tip equipped with actuators and sensors having the aim to morph the Wing. The calibration procedure of the Wing Tip is further presented, followed by the open loop controller results obtained during wind tunnel tests. Various methodologies of open loop control are presented in this paper, and results obtained were obtained and validated experimentally through wind tunnel tests
