Accession Number : ADP008909

Title :   Multi Location LDA Measurement in a Shock Tube,

Corporate Author : PHYSICAL RESEARCH INC TORRANCE CA

Personal Author(s) : Modarress, Dariush ; Hoeft, Thomas

Report Date : 23 JUL 1992

Pagination or Media Count : 6

Abstract : We describe a new experimental technique for obtaining fully-resolved measurements of the vector velocity field u(x,f) throughout a four-dimensional spatio-temporal region in a turbulent flow, and present examples of results obtained from of its application in a study of the fine-scale structure and dynamics of turbulent flows. The method uses fully-resolved four-dimensional scalar field imaging measurements to extract the underlying vector velocity field from the exact conserved scalar transport equation. The procedure for accomplishing this is summarized. Results from a test case in which an actual measured turbulent flow scalar field xi(x,f) is advected numerically by an imposed flow field allow a careful validation of the technique and its potential accuracy. Further results obtained by applying this new technique to extract the underlying structure of the vector velocity, vorticity, and tensor strain rate fields in a turbulent flow are also presented. These indicate that this scalar imaging velocimetry technique provides a novel means for experimentally studying the detailed physical structure and spatio-temporal dynamics of the dissipative scales of motion in turbulent flows. (Author)

Descriptors :   *LASER VELOCIMETERS, *SHOCK TUBES, DOPPLER EFFECT, FIBER OPTICS, SITE SELECTION, MEASUREMENT, SHOCK WAVES, BOUNDARY LAYER FLOW, FAST FOURIER TRANSFORMS, MULTICHANNEL, DATA REDUCTION.

Subject Categories : Test Facilities, Equipment and Methods
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE