Accession Number : AD0704121

Title :   THE EFFECT OF HIGH INTENSITY TURBULENCE ON THE AERODYNAMICS OF A RIGID CIRCULAR CYLINDER AT SUBCRITICAL REYNOLDS NUMBER.

Descriptive Note : Final rept. May 65-May 68,

Corporate Author : TORONTO UNIV (ONTARIO) INST FOR AEROSPACE STUDIES

Personal Author(s) : Surry,David

Report Date : MAR 1970

Pagination or Media Count : 207

Abstract : The interaction of high intensity turbulence with the flow past a rigid circular cylinder was studied experimentally at subcritical Reynolds numbers. Grids were used to produce homogeneous turbulence fields with longitudinal scales ranging from 0.36D to 4.40D, and with longitudinal intensities greater than 10%. Power and cross-spectra of the turbulence components (the 'system input') were measured in order to carefully define the turbulence characterists. In particular, lateral coherences of the longitudinal component were found to collapse well when plotted versus zeta/lambda (lateral separation/wavelength) as suggested by Davenport. A model with which measurement of arbitrary two-point pressure correlations could be made was used in the response experiments. Subsequent integrations yielded the spectral properties of the unsteady drag and lift. Measurement of mean drag and Strouhal frequency indicate that to some extent even severe large-scale turbulence can be considered equivalent to an increase in the effective Reynolds Number. Vortex shedding is not disrupted drastically by severe turbulence, but is affected more by that at low frequency than at high. The unsteady lift response is still dominated by the vortex shedding, whereas the unsteady drag is primarily a response to turbulence. The cross-spectra of the drag collapse well when plotted versus zeta/lambda, and were used, for one grid, to derive a 'describing function' for the drag 'response' to turbulence. This describing function is the central element needed for the calculation of structural response in the drag direction. (Author)

Descriptors :   (*AIRFRAMES, WIND), (*WIND, TURBULENCE), CYLINDRICAL BODIES, AERODYNAMIC LOADING, REYNOLDS NUMBER, INTENSITY, BOUNDARY LAYER, INTERACTIONS, DRAG, VORTICES, CANADA

Subject Categories : Aircraft
      Fluid Mechanics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE