Measurements in the flow field of a cylinder with a laser transit anemometer and a drag rake in the Langley 0.3 m transonic cryogenic tunnel
Abstract
An experiment was conducted at the 0.3 m Transonic Cryogenic Tunnel using a Laser Transit Anemometer (LTA) to probe the flow field around a 3.05 centimeter-diameter circular cylinder. Measurements were made along the stagnation line and determination of particle size was evaluated by their ability to follow the flow field. The LTA system was also used to scan into the boundary layer near the 45 degree point on the model. Results of these scans are presented in graphic and tabular form. Flow field particle seeding was accomplished by inbleeding dry service air. The residual moisture (5-10 ppm) condensed and formed ice particles which served as Mie scattering centers for the LTA detection system. Comparison of data taken along the stagnation streamline with theory indicated that these particles tracked the velocity gradient of the flow. Tunnel operating conditions for the tests were a Mach number of 0.3, a pressure of 1.93 x 100000 n/m squared, and a temperature of 225 degrees K. Free stream Mach number and pressure were varied for the particle size determination.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- April 1985
- Bibcode:
- 1985STIN...8524270H
- Keywords:
-
- Circular Cylinders;
- Cryogenic Wind Tunnels;
- Drag Devices;
- Flow Distribution;
- Laser Anemometers;
- Transonic Wind Tunnels;
- Boundary Layer Flow;
- Mie Scattering;
- Particle Size Distribution;
- Size Determination;
- Stagnation Point;
- Velocity Measurement;
- Wind Tunnel Tests;
- Instrumentation and Photography