Planar Doppler Velocimetry for Transonic Flowfields in the AEDC 16T Wind Tunnel

Over a period of several years, the AEDC Planar Doppler Velocimetry (PDV) system has been developed for use in the 16by 16-ft square test section of the 16T Propulsion Wind Tunnel to obtain transonic off-body flow measurements around large-scale test articles. The demonstration described in this paper was part of a facility checkout project that involved the use of a standard calibration check model (the Facility Aerodynamics Validation and Operations Research, or FAVOR, test article). For this PDV demonstration in 16T, a continuous-wave laser light source is used, one that has a narrower laser linewidth than the pulsed laser that has been used in previous 16T-PDV demonstrations. The continuous-wave laser allows fiber optic beam delivery into the test cell, greatly improving the practicality of using PDV in 16T. Another system improvement related to ease-of-use is the implementation of coherent fiber optic imaging bundles to provide PDV images to the iodine cell/camera systems. Velocity data from a region 36-in. wide by 30-in. tall, located just behind the model, were obtained for two supersonic Mach numbers and four model pitch angles. Measured freestream velocities and measured crossflow velocities were obtained. Overall accuracy in the measured data, for both freestream and crossflow velocity measurements, is estimated at ±15% of freestream velocity.