Laser Doppler anemometry: recent developments and future challenges

The availability of new optical and electronic components and the increasing demands on measurement accuracy have led to a continuous development of the laser Doppler measurement technique in recent years. This article reviews the developments in optical systems, signal processing, data processing and in the application of LDA systems. Particular emphasis is placed on examining how well present instruments meet the changing needs of the fluid mechanics community and what improvements would be desirable in the near future. Cam Tropes was born in instrumentation developments in the field of laser Doppler Toronto, Canada, where he alSO a,,ended the University anemometry, rather than on the broad range of applications. of Toronto to earn a BASc NO new results are presented, hut some attempt is made in Engineering Science and to evaluate the importance of the respective developments, an MASc in Mechanical Enimplicitly through the choice of material presented and gineering. He continued his explicitly by examining current experimental needs in fluid studies in Karlsruhe. Germany, where he completed mechanicS. a Or-lng, in 1982. and after The volume of literature on the LDA technique is which he moved to the Uniimmense and, indeed, is one of the problems facing the versity Of Erlangen-Nurnberg, interested researcher. In the present review, reference will Germany as a research asbe made to a large number of specific works, but general sociate. With one year as a visiting Assistant professor at reference sources are also valuable, especially for those the University of Waterloo, Canada. he completed his readers interested in the principles and the evolution of Habilitation in 1991 at Erlangen, before joining the company the technique. For example, the pioneering developments Invent GmbH. also in Erlangen, where he stayed for almost of LDA have bee,, collected in a recent volume edited by Adrian [I]. Unfortunately, most textbooks on the two years. He returned to the University in Erlangen as Professor of Fluid Mechanics in 1992, where he is presently employed. He has worked extensively on the development LDA technique are somewhat older and no longer reflect of LDA and PDA measurement systems and their application the state of the art in equipment; however, they remain to complex flow situations. valuable as an introduction to the principles [ 2 4 ] . Several conference series have been instrumental in promoting