Measurements in fluid flows using filtered Rayleigh scattering

Filtered Rayleigh scattering is a non-intrusive optical diagnostic technique that utilizes the light scattered from the air to allow the computation of thermodynamic properties and velocity in flow fields. Rayleigh scattering was produced by the non-resonant reradiation of light by air molecules. The characteristics of the scattering are functions of the thermodynamic properties and velocity of the fluid. This measurement technique is able to resolve the scattering spectral characteristics and allows the determination of the underlying thermodynamic state and velocity of the fluid.; The goals of this dissertation are to develop FRS for flow measurements and improve data reduction routines and procedures in order to make the technique more versatile and applicable in a wider variety of environments. Also to improve system components in order to obtain more accurate measurements. To apply the technique to flows of current research interest and thus advance the body of knowledge in certain fluid mechanic applications and to evaluate errors and uncertainties pertaining to the technique and the experiment in consideration. Another goal of this work is to develop FRS techniques to be used in studies in our laboratory and for others that we have collaborated with.; A number of examples are introduced and studied with FRS flow visualization. Next the system is used for single-property measurement. The system was capable of yielding two-dimensional temperature fields. Four different fluid flows are studied using this method. Then the technique is used to obtain simultaneous measurements of thermodynamic properties and velocity. Two experiments are performed that yield planar average fields of density, temperature and velocity. Finally an arrangement is studied in which instantaneous multi-property measurements are obtained at a point.; Improvements of the FRS numerical model were made so that it was possible to measure background scattering without the need of changing the gas species or use vacuum chambers to eliminate the molecular scattering from the region of interest. In this manner, the cost of the experiments, in terms of laboratory equipment and level of sophistication, is greatly reduced making the technique easier to perform in a wider variety of circumstances.