Optical Measurements

Increasing possibilities of computer-aided data processing have caused a new revival of optical techniques in many areas of mechanical and chemical engi­ neering. Optical methods have a long tradition in heat and mass transfer and in fluid dynamics. Global experimental information is not sufficient for de­ veloping constitution equations to describe complicated phenomena in fluid dynamics or in transfer processes by a computer program. Furthermore, a detailed insight with high local and temporal resolution into the thermo­ and fluiddynamic situations is necessary. Sets of equations for computer program in thermo dynamics and fluid dynamics usually consist of two types of formulations: a first one derived from the conservation laws for mass, energy and momentum, and a second one mathematically modelling transport processes like laminar or turbulent diffusion. For reliably predicting the heat transfer, for example, the velocity and temperature field in the boundary layer must be known, or a physically realistic and widely valid correlation describing the turbulence must be avail­ able. For a better understanding of combustion processes it is necessary to know the local concentration and temperature just ahead of the flame and in the ignition zone.

This book provides an introduction to the most important optical measurement techniques that are applied to engineering problems. It will also serve as a guideline to selecting and applying the appropriate technique to a particular problem. The text of the first edition has been completely revised and new chapters added to describe the latest developments in Phase-Doppler Velocimetry and Particle Image Velocimetry. The editors and authors have made a special effort not only to describe and to explain the fundamentals of measuring techniques, but also to provide guidelines for their application and to demonstrate the capabilities of the various methods. The book comes with a CD-ROM containing high-speed movies visualizing the methods described in the book.