Turbulence measurements with a Laser Doppler Velocimeter (LDV) using the dual scatter or differential Doppler mode have been made in a subsonic, fully developed channel flow. The measurements were made using only those light scattering particles occurring naturally in air. Results include mean velocity profiles, turbulence intensities, Reynolds stress distributions and a skewness measurement of the velocity distribution function across the channel. Statistical techniques were used to obtain the various turbulence parameters. Guidelines have been established for the amount of data needed to obtain results with a specified accuracy and confidence level. Measurements have also been made to determine the particle-size distribution. An aerodynamic means was used to determine the size distribution, in contrast to the usual optical procedures. (Modified author abstract).

The contents of this volume reflect to a large extent the efforts made by a group of Institutes at the ETH Zürich to develop new techniques for measurements of flows in fluids in the last decade. The motivation came from the study of tr~sport and mixing processes in natural and industrial systems. One of the characteristic properties of turbulence is its high mixing efficiency. The techniques developed are therefore suitable, although not exclusively, for turbulence measurements. They can be subdivided into point-measurements and field-measurements. The aim of the point-measurements developed is to determine the three components of the velocity and all their first derivatives with good temporal resolution and accuracy in turbulent flows. The old and weIl established method of hot-wire anemometry was used for this purpose. One of the main achievements in this context is the construction of miniature multi-wire probes. This technique was introduced to the Institute of Hydromechanics and Water Resources Management of ETH Zürich by Profs. A. Tsinober and E. Kit from Tel-Aviv University. This was made possible by the generous financial support by ETH, for which I would like to express my gratitude on this occasion. In addition, Dr. F.E. Joergensen from DANTEC contributed an example of recent developments in the hardware ofConstant Temperature Anemometry (CTA), for which I am very thankful.

Three-dimensional laser doppler velocimeter measurements were made of the velocity distribution in a supersonic inner jet mixing with a subsonic outer flow. Experimental data for mean flow velocities (u, v, w), turbulent intensities ((u') squared, (v') squared, (w') squared), and turbulent velocity correlations (u'v', u'w', v'w) are presented for both hot and cold exhaust plumes produced by a small kerosene/gaseous oxygen rocket engine operating at nominal chamber pressures of 50 and 150 psig. The outer flow was maintained at 200 ft/sec. Velocity profiles were obtained in the radial direction at various axial locations (X/D sub E=2.4, 4.8, 8.4, 11.3, and 14.2). The velocity profile along the centerline of the jet was obtained for the cold flows and showed the presence of shock waves at various axial locations. (Author).