Transient Temperature in Engineering and Science

Abstract

Temperature measurement is such a long-established branch of instrumentation that one might be forgiven for thinking, mistakenly, that it offers little further challenge. The authors leave no doubt that advances in detection, data acquisition and processing have led to significant contributions to our understanding of transient temperature phenomena such as combustion processes. They take as their scope temperatures between 200 K and 6000 K, with time-scales from nanoseconds to tens of seconds. The book has ten chapters grouped into fundamentals, measurement techniques and applications. Although `engineering' precedes `science' in the book's title, the first chapter lays a foundation firmly based on thermal physics. It begins by quite properly examining the various concepts of temperature, the connection between macroscopic and microscopic descriptions, kinetic theory, equilibrium and non-equilibrium processes and the definitions of temperature scales. Chapter 2 covers analytical solutions for heat conduction in solids and convective heat transfer in gases. Mathematical techniques like the Laplace transform and numerical solution methods are reviewed before their application to the cases of temperature transients in semi-infinite solids. Convective heat transfer is treated briefly in terms of an energy equation and as an experimental correlation between dimensionless numbers describing the flow. Chapter 3 completes the survey of fundamentals by examining the topics of radiation transport, spectroscopy and absorption and scattering by particles, such as soot particles in flames. The chapters on measurement techniques start with thermocouples, from a thermodynamic description to practical details of their construction, packaging, circuitry and response times. Resistance thermometry, `cold-wire' resistance sensors and surface film gauges are dealt with in some detail. However, the dual hot-wire aspirating probe for total temperature measurement in aerodynamic flows is not mentioned. The advantage of non-intrusive radiometry in determining flame temperature is the subject of chapter 5. This is followed by a chapter on tomographic methods of revealing the spatial distribution of absorption and emission coefficients and temperature within a radiating volume such as a gas flame. The final techniques to be described are laser-based methods: Raman spectroscopy (spontaneous scattering and CARS) and laser-induced fluorescence. The authors go on to describe some of these techniques applied to their own research areas - the performance of internal combustion engines and gun barrels. These are particularly demanding measurement problems, and are probably unfamiliar to many readers. The book concludes with a chapter describing failure in materials subjected to thermal transients. In addition to references, each chapter contains a useful list of nomenclature. Overall, the book successfully blends basic scientific concepts and engineering applications. The fundamentals are very clearly described at a level appropriate to final-year undergraduates, while the details and case studies will be of value to scientists and engineers wishing to measure thermal transients.