DEVELOPMENT AND UTILIZATION OF A LASER VELOCIMETER SYSTEM FOR A LARGE TRANSONIC WIND TUNNEL.

The need for measurements of the velocity flow field about spinner-propeller nacelle configurations at Mach numbers to 0. 8 was met by a specially developed laser velocimeter system. This system which uses an argon-ion laser and 4-beam 2-color optics was required to operate in the hostile environment associated with the operation of a large transonic wind tunnel. To overcome the conditions present in locating the sensitive optics in close proximity to the wind tunnel, an isolation system was developed which protects the velocimeter from the high vibrations, elevated temperatures, destructive acoustic pressures and low atmospheric pressures. The system has been utilized to map the flow field in front of, behind, and in between the rotating blades of an advanced swept-blade propeller model at a Mach number of 0. 8.