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Technical Paper

Relationship of Wing Drag to Entropy Production

Much of the basic understanding of aerodynamics is a result of research conducted in the early part of the twentieth century. A prominent example is the understanding of the cause of the drag due to lift, or induced drag. In this explanation the drag due to lift is connected with the trailing vortices that can be seen behind a wing. In this paper an explanation is derived for the existence of all wing drag, including drag due to lift. The drag formulation arises from the relationship of surface pressure to entropy generated predominantly by vorticity in the flow field. This new formulation allows the total drag to be split into the contributions made by different flow features. It also leads to suggestions on how to reduce drag
Technical Paper

Simple Adaptive Planforms For Wings

One of the major constraints in developing practical adaptive wings is that they must be easy to install and maintain and be relatively inexpensive. This constraint implies that some recent proposals for wing “morphing”, such as those that require large geometric movements, will not be installed in a production air vehicle. The approach reported in this paper is to investigate ways of improving aerodynamic performance that do not require large geometric movements. The geometry changes used in the current research are leading and trailing edge “waves’ that have a deflection of 1%–2% of chord.
Technical Paper

Macro-Aerodynamics: – A Phenomenological Model of Highly Non-linear Aerodynamics

Aerodynamics is a non-linear, dynamic, system and thus has the capacity to produce different flows for the same boundary conditions. Generally both experiments and computational studies will give only one of these flows. The research presented in this paper is directed at developing a non-linear, dynamic, system that models aerodynamics satisfactorily but allows control of various aerodynamic elements so that the nature of possible, not necessarily probable, bifurcations and other forms of non-linear behavior can be studied. It is expected that such behavior may occur in the type of extreme aerodynamic conditions that are precursors to aircraft accidents.
Technical Paper

A Phenomenological Model of Dynamic Stall

Dynamic stall has been the subject of much research but there is still some uncertainty about several aspects. Almost all research to date has involved experiments or computational fluid dynamics, both, in essence, trying to duplicate the phenomena. The present research takes a different tack by trying to develop a phenomenological model that will allow greater insight into the relationship between various physical elements that are present in the flow. The research indicates a fairly simple explanation for dynamic stall and identifies the controlling factors.