16:00
Gust 5
Chair: Héctor Climent
16:00
30 mins
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A high aspect ratio wind tunnel model for transonic gust load alleviation with active control
Huub Timmermans, Andres Jurisson, Wolf Krueger, Johannes Dillinger, Kees Kapeteijn, Felix Stalla
Abstract: The Clean Aviation Project called “Ultra-Performance Wing” (UP Wing) develops, matures and demonstrates key technologies and provides the architectural integration of ultra-performance wing concepts for short-medium range (SMR) aircraft with 150 to 250 passengers and 500 to 2000 nm range. One of the key technologies within the UP Wing project is “Novel Control Technologies” leading to a reduction in wing loads by applying manoeuvre and gust load alleviation technologies. To validate and compare different control methods best suited for gust load alleviation an aero-servo-elastic windtunnel test will be performed. This paper describes the design and corresponding analyses for a highly flexible wind tunnel model including several active control surfaces. The wind tunnel model will alleviate the gust loads by means of fast actuating control surfaces. One of the key challenges is to fit actuators within the available space that are both fast and able to overcome the moments generated by the control surfaces in transonic test conditions. To alleviate the loads, several control methods are investigated by different partners using a state space model created from the initial structural model and the aerodynamic panel model. To test the novel load alleviation function concepts during the wind tunnel test, a disturbance in the flow field will be generated. This is done by means of gust generator ahead of the test section. Several possibilities are investigated using Computational Fluid Dynamic analyses to see the resulting disturbance at the location of the wind tunnel model.
The paper provides an overview of the past and upcoming activities related to the design of a flexible high aspect ratio wind tunnel experiment within the UP Wing Project.
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16:30
30 mins
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Gust load alleviation wind tunnel tests of a folding wing tip configuration
Luca Marchetti, Sergio Ricci, Luca Riccobene, Donato Grassi, Paolo Mantegazza, Stephan Adden, Huaiyuan Gu, Jonathan Cooper
Abstract: Increasing the aspect ratio is one way to improve aircraft aerodynamic efficiency. This reduces the induced drag term but, at the same time, produces an increment of the wing loads, hence an increase of the structural weight.
This paper reports the results obtained during a dedicated experimental campaign inside the large wind tunnel at Politecnico di Milano exploring the gust load alleviation capability of a folding wing tip device. This activity has been done under the umbrella of CS2-U-HARWARD project. The high aspect ratio wing equipped with this device was mounted on a half aircraft lying on its side.
The model could freely rotate around its pitching axis and a sledge allowed the entire model to plunge. An electromagnetic actuator allowed the application of a dummy weight force to the aircraft counteracting the lifting force, hence permitting the trim of the aircraft. The gusts were produced by deflecting six vanes in front of the model, with different gust lengths produced to excite different frequencies of the wing. A pneumatic actuator was used to keep the wing tip in its standard configuration and release the mechanism allowing it to fold at will.
Several delays between the triggering of the gust and the release of the hinge mechanism were tested, to assess the coupling between the dynamics induced by the gust and the one induced by the release of the mechanism. Three strain gauge bridges were installed on the spar of the wing to measure the bending moment at three different sections corresponding to the root, the engine and as near as possible to the hinge. In addition, a camera tracking system composed of six infrared cameras allowed the reconstruction of the 3D motion of the wing hit by the gust and the complex dynamics of the folding wingtip. The measured wing root bending moment shows that the amount of load alleviation depends on the time when the gust hits the folding wing tip. The wing tip needs to be free to float when the gust hits it for the alleviation to be effective, but the transient of the unlocking of the hinge seems to be beneficial to the goal.
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17:00
30 mins
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Wind tunnel tests for gust load investigation in transonic flows – Part 1 : Development of an innovative test rig
Arnaud Lepage, Nicola Paletta, Serena Russo, Sergio Ricci, Eric Rantet, Arnaud Barnique
Abstract: The development of load predictions capabilities and load control strategies is a key axis for enhancing the design process of the next aircraft generation, with the aim of significantly reducing fuel consumption levels. Within the Clean Sky 2 AIRFRAME ITD framework, a specific objective is dedicated to addressing the gust load case, which is crucial for strength design and fatigue loading source for transport type aircraft particularly in the certification process.
Building on the accomplishments of the Clean Sky SFWA-ITD project [1], a new experimental research program has been established, centred around Wind Tunnel Tests (WTT) conducted at the transonic ONERA S3Ch facility. The primary goals of this program were to deepen our understanding of gust effects, particularly in the non-linear domain, and to advance the maturity of load control approaches.
The initial phase of these studies has been conducted within the framework of a project called GUDGET, aimed at developing an innovative test rig for investigating gust loads, particularly challenging in the transonic regime. Based on pre-design solutions provided by ONERA, new gust generation devices have been analysed, designed and manufactured in order to deliver deterministic vertical and harmonic gusts with larger amplitude and in a wide frequency range [2]. Two main concepts consisting in a tandem of airfoils installed horizontally right upstream of the test section were studied, based on either dynamically moving airfoils or fixed vanes equipped with pulsed blowing slots.
To investigate the effects of gusts on the aerodynamic and aeroelastic behaviour of a model, the test rig also included a wall-mounted half-wing model. This model was heavily instrumented and equipped with a suitable aileron located close to the wingtip, which was remotely actuated using a high-frequency actuation system to demonstrate real-time active gust load alleviation.
Finally, the results of a first WTT campaign, carried out to qualify the unsteady flow induced by the various gust generation capabilities, are presented. The outcomes of a second WTT dedicated to analysing gust effects on the model aeroelastic behaviour for different structural and aerodynamic conditions, are presented in a companion paper [3].
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17:30
30 mins
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Wind Tunnel Tests for Gust Load Investigation in transonic flows – Part 2: Experimental results and control demonstration
Vincent Bouillaut, Alex Dos Reis De Souza, Pierre Vuillemin, Charles Poussot-Vassal, Arnaud Lepage
Abstract: Aerodynamic loads are a recurrent topic in aeronautical research. Indeed, during a flight, a wing can endure a wide variety of load sources impacting significantly the aerodynamical performances of the aircraft. Regarding those problematics, aeronautical studies aim to understand and find ways to decrease the effects of those disturbances.
The present work focuses on one of those sources: the vertical gust, a particularly common phenomenon, responsible for important alterations of the airflow around the wing profile. To reproduce its effect, a gust generator has been installed in the contraction section of the S3Ch transonic wind tunnel at the ONERA Meudon center.
The present study first introduces the gust generator used in this wind tunnel experiment. It is composed of two wings located upstream of the model. The two wings oscillate, hence creating vortices that will be carried by the flow stream to the model.
Then, the effects of the gust are described, in both subsonic and transonic (up to Mach 0.82), on the aerodynamics and the aeroelastic response of a heavy instrumented (accelerometers, pressure sensors, strain gages) half wing fuselage model. In addition, an optical methodology gives access to deformation measurements of the model, thus giving a global picture of the phenomenon.
Finally, a gust load alleviation methodology based on an active feedback loop is presented. A real-time device has been used and linked to a movable aileron of the model. A control algorithm based on several input sensors is implemented in the real-time device to decrease the effects of the gust load on the structural dynamics of the model. The results of this active control experiment will be discussed.
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