Doctoral thesis (Dissertations and theses)
Experimental Investigation of the Aerodynamics and Aeroelasticity of Flapping, Plunging and Pitching Wings
Norizham, Abdul Razak
2012
 

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Keywords :
Flapping wing; Stall flutter; Dynamic stall
Abstract :
[en] This thesis concerns the experimental analysis of the aerodynamics and aeroelasticity of oscillating wings. It is divided into two sections, an inves- tigation of wings undergoing imposed root flapping and pitching motion, such as seen in avian flight and an experimental investigation of the self- excited stall flutter oscillations of a wing undergoing plunging and pitching motion. The objective of the flapping wing investigation is to improve the under- standing of the unsteady aerodynamics of flapping flight. The work con- sists of designing and building a flapping and pitching bird-like mechanical model and testing it in a low speed wind tunnel. The model’s size is sim- ilar to that of a goose. The wind tunnel tests involved the measurement of forces, power, kinematics and local flow velocities using Particle Im- age Velocimetry (PIV). The mechanical model was tested at four different frequencies and three airspeeds. In addition, three different wing profiles were tested. The kinematic modes included pure flapping and combined flapping and pitching. It was shown that pure flapping and pitch-lagging combined motion can lead to interesting aerodynamic phenomena, such as flow separation and dynamic stall. Dynamic stall can cause significant increases in instantaneous lift production, although it also generates a lot of drag. On the contrary, pitch leading combined motion can generate a net propulsive force over the entire cycle. In the stall flutter study, a 6 degree of freedom NACA 0018 wing was sus- pended by springs in the wind tunnel. The wing was then exposed to an airflow at a number of airspeeds and wind-off angles of attack. The wing was instrumented with pressure sensors and accelerometers. In addition, PIV flow measurements were carried out on the wing’s upper surface. The work demonstrates that stall flutter is the result of a combination of dy- namic stall with the elastic properties of the system. The dynamic stall mechanism was studied using the PIV measurements and was found to be different to the classical stall mechanisms that are reported in the litera- ture. The sensitivity of the stall flutter phenomenon to parameters such as airspeed and wind-off angle of attack is demonstrated by means of a two-parameter bifurcation diagram.
Research center :
Aeroelasticity and Experimental Aerodynamics
Disciplines :
Aerospace & aeronautics engineering
Author, co-author :
Norizham, Abdul Razak ;  Université de Liège - ULiège > Département d'aérospatiale et mécanique > Interactions Fluide-Structure - Aérodynamique expérimentale
Language :
English
Title :
Experimental Investigation of the Aerodynamics and Aeroelasticity of Flapping, Plunging and Pitching Wings
Defense date :
15 May 2012
Number of pages :
234
Institution :
ULiège - Université de Liège
Degree :
Doctor in Engineering Sciences
Promotor :
Dimitriadis, Grigorios ;  Université de Liège - ULiège > Aérospatiale et Mécanique (A&M)
President :
Bruls, Olivier  ;  Université de Liège - ULiège > Département d'aérospatiale et mécanique
Jury member :
Noels, Ludovic  ;  Université de Liège - ULiège > Aérospatiale et Mécanique (A&M)
Terrapon, Vincent  ;  Université de Liège - ULiège > Département d'aérospatiale et mécanique
Poirel, Dominique
Nudds, Robert
Hendrick, Patrick
Available on ORBi :
since 21 May 2012

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