<title>Suitability of optical techniques for investigating complex flows in difficult environments</title>

Abstract

In recent years, laser based optical techniques have been extensively used in industry to investigate flow. The main application areas vary from complex flow fields in rotating turbomachines to complicated twophase gas/liquid and liquid/liquid flows. Several measuring systems, based on optical techniques, are commercially available which include Laser Doppler system, Phase Doppler System, Laser Diffraction System and Scanning Laser microscope. The choice of the measuring system mainly depends on the information required and the nature of flow fields involved. This paper describes the limitations and the general problems of some of these measuring techniques. Results from several experimental rigs have been presented and in some cases measurements from two different optical systems have been compared for identical flow conditions. The discrepancy in results have been explained to justify the use of these techniques.

<title>Droplet size distributions in waveplate demisters using optical techniques</title>

“…A very delicate optical alignment is required for its accurate performance. The problems associated with this system when operated in the harsh environment of running rigs have been explained elsewhere by Zaidi [23,24,25]. …”