Accession Number : ADP000341

Title :   Some Advantages of Unsteady Aerodynamics,


Personal Author(s) : Viets,Hermann

Report Date : JUN 1982

Pagination or Media Count : 19

Abstract : With few exceptions, aerodynamicists have historically considered unsteady flow as detrimental to performance. Two notable examples are the problems of inlet buzz and wing flutter while the performance of the pulsed combustion missiles of the 1940's is a prominent exception. In some situations unsteady flows are unavoidable, as in the case of rotating compressors and turbines. In these and other situations, it is of interest to examine the time dependence from a positive point of view. That is; if unsteadiness is deliberately introduced or amplified, are there potential performance advantages? It is the purpose of this paper to examine several recent and ongoing experiments which involve the attempt to improve performance by utilizing unsteady flow. Two areas are described. The first is the introduction of unsteadiness into a boundary layer by mechanical means. The aim is to energize the boundary layer to avoid or lessen problems resulting from separation. A second area is the unsteadiness. The time dependency can be completely fluidically produced or it can be driven by a mechanical-fluidic interface. (Author)

Descriptors :   *Aerodynamic stability, *Unsteady flow, *Time dependence, *Boundary layer flow, Separation, Control systems, Rotors, Ramps, Nozzles

Distribution Statement : APPROVED FOR PUBLIC RELEASE