Accession Number : ADA306706

Title :   The Source and Evolution of Turbulence in Trailing Vortex Pairs.

Descriptive Note : Final rept.,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCE AN ENGINEERING

Personal Author(s) : Vogel, Christine M. ; Devenport, William J.

PDF Url : ADA306706

Report Date : APR 1995

Pagination or Media Count : 256

Abstract : The reanalysis of data obtained from the experimental studies of two different trailing vortex pairs has been conducted to obtain a more complete understanding of the turbulence structure of these flows. Statistical and spectral results, as well as filtered results and estimates of the effects of vortex wandering on the characteristics of the flows are presented. The results of the vortex pair are compared with the data from the experimental study of an isolated vortex conducted under similar testing conditions and model configuration to distinguish between the structure and effects of the separate vortices from those of vortex interaction. The analysis of a counter-rotating vortex pair reveals that initially the vortices develop in a manner similar to an isolated vortex. The cores appear laminar and the turbulence structure outside them is dominated by the spiral wakes. After some distance, flow inside and outside the cores becomes much more turbulent. The cores begin to grow and decay. The results indicate that this change may be a result of wave instabilities developed in the cores. The analysis of the co-rotating vortex pair reveal that turbulence is present in the cores as they spiral about each other and move downstream. After a certain distance, the cores merge into a single core, which contains more turbulence and is over twice the size of the pair that created it. As merger comes to completion, a symmetric core is formed which has much less turbulence. Merger appears to cause an increased rate of vortex decay.

Descriptors :   *TURBULENCE, *TRAILING VORTICES, VELOCITY, STRESS STRAIN RELATIONS, MATHEMATICAL MODELS, STRESS ANALYSIS, TURBULENT FLOW, COMPUTATIONAL FLUID DYNAMICS, FLOW VISUALIZATION, VORTEX SHEDDING, PRESSURE MEASUREMENT, FLOW FIELDS, DATA REDUCTION, AERODYNAMIC FORCES, WAKE, FREE STREAM, LAMINAR FLOW, INSTABILITY, PRESSURE DISTRIBUTION, HOT WIRE ANEMOMETERS, AXIAL LOADS, COUNTERROTATION, AXIAL FLOW, CROSS FLOW.

Subject Categories : Fluid Mechanics
      Aerodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE