Characterisation of wind tunnel observed, large-amplitude pitch limit-cycles

Pattinson, John; Löwenberg, Mark; Goman, Mikhail

doi:10.2514/6.2011-6526

Cited by 7 publications

(6 citation statements)

References 15 publications

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“…It is believed that such an experimental set-up will be more common in the future as it de-risks expensive demonstrator flight tests when testing flexible HARW models. When considering flexible aircraft, the ability of the numerical model to capture and reproduce geometrical and aerodynamic nonlinearities is crucial to investigate aeroelastic instabilities such as Limit Cycle Oscillations (LCO) [17,18], flutter and flight dynamics/structural coupling. While this problem could be investigated using high-fidelity numerical models, such as 3D Finite Element Methods (FEM) for structures coupled with Computational Fluid Dynamics (CFD) for aerodynamics, this work focuses on a low-order approach.…”

Section: Fig 1 Aspect Ratio Trend For Commercial Aircraft [6]mentioning

confidence: 99%

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Low-order Aeroelastic Modelling of a High Aspect Ratio Wing Aircraft Under Constrained Motion

Pontillo

Navaratna

Ascham

et al. 2022

AIAA SCITECH 2022 Forum

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The work presented in this paper describes the modelling of a low-order aeroelastic solver, built with the aim of analysing the dynamics of very flexible wing aircraft, with a focus on the coupling between the flight dynamics and the structural dynamics. The model implements a geometrically exact, low-order nonlinear beam solver based on beam shape functions coupled with Vortex Lattice Method (VLM), specifically adapted to account for large deformations. The static solution calculated by implementing the VLM was compared with the one calculated using strip theory as aerodynamic solver, showing good agreement in magnitude, but different load distribution. The aeroelastic solver was then used to analyse the dynamics of a flexible aircraft constrained to a circular trajectory with free pitch (resembling the motion on a Pendulum Rig) and on a spherical motion with free pitch and yaw (resembling the motion on the University of Bristol 5-DOF Manoeuvre Rig), for two different values of pitch stiffness and three different flexible wings (5% deflection, 10% deflection and 15% deflection with respect to the wing semispan). The results show that when the stiffness is high, it suppresses any interaction between the flight dynamics and the structural dynamics. Therefore there is no impact of the wing flexibility on the aircraft motion. On the other hand, when lowering the value of the pitch stiffness, the interaction between the wing dynamics and the pitch dynamics become evident. However, the impact of the wing flexibility was found to be always negligible on the yaw dynamics.

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Section: Fig 1 Aspect Ratio Trend For Commercial Aircraft [6]mentioning

confidence: 99%

“…Manoeuvre Rig[15,18,29]. To reproduce the dynamics of the model on the 5-DOF rig, the model was constrained to a spherical surface, as shown in Figure8a.…”

mentioning

confidence: 99%

Low-order Aeroelastic Modelling of a High Aspect Ratio Wing Aircraft Under Constrained Motion

Pontillo

Navaratna

Ascham

et al. 2022

AIAA SCITECH 2022 Forum

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“…The resulting 'physical simulation' allows for the observation of aircraft behaviour, including the influence of nonlinear and/or time-dependent aerodynamics such as that responsible for the onset of upset/departure; and the motion data from such tests -or from forced motions driven by the rig compensator system -can then be used to carry out parameter estimation for mathematical model development. A couple of prototypes of the manoeuvre rig have been developed recently to obtain aerodynamic data from wind tunnel multi-DOF dynamic tests, 14 to characterise the oscillatory longitudinal pitch and heave motions of an aircraft model 15 and to numerically simulate free flight manoeuvres of a delta-wing aircraft model in a wind tunnel. 16 Following the development and initial testing of this rig concept at the University of Bristol, 17 various follow-on activities were identified.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Aircraft Model Upset Behaviour Using Wind Tunnel Manoeuvre Rig

Araujo-Estrada

Löwenberg

Neild

et al. 2015

AIAA Atmospheric Flight Mechanics Conference

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This paper discusses the development of a novel multi-degree-of-freedom dynamic manoeuvre rig aimed at investigation of aircraft upset/LOC-related behaviour in the wind tunnel. The motivation behind the development and characteristics of the rig are first described, along with example behaviour of an aircraft model exhibiting nonlinear timedependent aerodynamics in an open-jet low-speed wind tunnel. Test objectives for assessment of upset onset scenarios -both for parameter estimation purposes and to 'physically simulate' the behaviour -are then described, as is the design of the upgraded instrumentation system to facilitate experimental investigastion. Finally, examples of relevant behaviour involving real-time control of the rig to explore nonlinear conditions leading to upset are presented; these are evaluated in terms of prospects for such testing in aircraft development and analysis projects.

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“…Experimental rigs such as the 5-DOF maneuver rig have previously been used to study nonlinear and time-dependant aerodynamic effects, as well as for the development of mathematical models via parameter estimation and aerodynamic characterization of model aircraft [6,7,8,9,10]. Here, we investigate the effect of the kinematic constraints on the aircraft model dynamics.…”

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confidence: 99%

Minimally Constrained Flight Simulation in Wind Tunnel

Navaratna

Lowenberg

Neild

2019

Journal of Aircraft

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Experimental studies into aircraft stability and performance can be enhanced by using a rig in which the aircraft model support approximates free flight within a wind tunnel.Such multi-degree-of-freedom wind tunnel rigs often impose kinematic restrictions on the aircraft model's translational motion. This study investigates these kinematic effects, with particular attention to a spherical constraint where the aircraft is held at the end of a fixed length pivoting arm. Here the motions of the aircraft and kinematic constraints are derived as differential-algebraic equations and assessed numerically. The impact is found mainly on translational motion with negligible effect on the aircraft's rotation. A concept to reduce these kinematic effects on the aircraft's motion by applying an external force onto the aircraft is proposed. This compensation, which partially accounts for the constraints on the aircraft motion, is shown to reduce the effects of the arm, allowing for improved physical simulation.

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Characterisation of wind tunnel observed, large-amplitude pitch limit-cycles

Cited by 7 publications

References 15 publications

Low-order Aeroelastic Modelling of a High Aspect Ratio Wing Aircraft Under Constrained Motion

Low-order Aeroelastic Modelling of a High Aspect Ratio Wing Aircraft Under Constrained Motion

Evaluation of Aircraft Model Upset Behaviour Using Wind Tunnel Manoeuvre Rig

Minimally Constrained Flight Simulation in Wind Tunnel

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