Automation and Extension of LDV (Laser-Doppler Velocimetry) Measurements of Off-Design Flow in a Subsonic Cascade Wind Tunnel.

摘要

A two-component laser-Doppler velocimetry system was successfully automated to speed the data acquisition and reduction process for flow measurements in a subsonic linear cascade wind tunnel. A three-axis traverse table was installed for computer controlled positioning of the LDV probe volume and a modification was made to permit measurements close to test blade surfaces. Commercial software was used for control and acquisition of the LDV data. Software was generated in-house to record tunnel conditions and to reduce and present the survey data. Detailed measurements were made of the flow through a controlled diffusion compressor cascade at an inlet flow angle of 48 degrees (8 degrees above design) to extend a database for viscous code validation. Test conditions were held nominally at M=0.25 and Rec=720000. The flow was shown to remain attached at the blade trailing edge but the measurements also indicated the presence of a less stable flow field in the blade passage when compared with previous observations at lower inlet flow angles. Keywords: Theses, Fighter aircraft, Jet fighters, Turbomachinery, High angle of attach aerodynamics. (kr)