Abstract
The first two chapters of this thesis comprise a review of laser anemometry with particular reference to photon correlation techniques. Chapter 3 discusses the requirement for and design and performance predictions of a new, versatile backscatter laser anemometry optical system capable of both laser Doppler and laser transit modes of operation. Comparisons of the new laser anemometer with hot and pulsed wire anemometry in an axi-symmetric jet are presented in Chapter 4. Chapter 5 describes the theory and simulations of a new method of photon correlation laser Doppler-difference anemometry using polarisation coded laser beams. The new technique permits determination of the velocity probability density function under conditions of flow reversals, without the use of frequency shifting. Comparisons of this new technique with pulsed-wire anemometry in an axi-symmetric baffled jet are presented in Chapter 6. Chapter 7 discusses further the results of the research comprising this thesis and provides a brief account of applications of the new instrumentation and techniques to some difficult problems in fluid engineering.