Laser Doppler Velocimeter for Measuring Flow-Velocity Fluctuations

Abstract

Instantaneous flow velocities in an unsteady liquid flow have been measured using optical heterodyning techniques. Flow in the transition region, as well as fully developed turbulence, was measured and compared with existing data and theory.

The Turbulent Free Convection Flow Above a Heated Horizontal Circular Plate

“…Toward the low end of the velocity range of interest, hot-wire techniques suffer from orientation effects due to local perturbation of the flow by the hot-wire itself. Recently, laser doppler techniques (14,15) have been developed which may obviate most of the difficulties associated with hot-wire techniques. However, these techniques appeared after the hotwire measurements reported in this thesis were well underway, and were not used for the present work.…”

“…An equation similar to (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) may be obtained 152 I m, 2 from the principle of conservation of mass. This may be used to chec the results of Equation (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16).…”

“…Calculate u'i,j and v'i' j for all interior points using Equation (6)(7)(8)(9)(10)(11)(12)(13)(14) a the stream function just calculated.…”