Design, realisation and performance evaluation of a high accuracy wake drag measurement device for CIRA transonic wind tunnel

A new wake rake for drag measurement in the CIRA transonic wind tunnel PT-1 has been designed and realised for 2D airfoil characterisation. Accuracy requirement was indicated as /spl plusmn/1 count in transonic regime, to be satisfied at all angle of attack conditions without needs for repositioning the device, and to be achieved with no more than 64 total pressure measurement position; this last requirement stemmed from the very high cost of the data acquisition system electronic pressure scanners. Besides, blockage minimisation, ability to measure wave drag, possibility to measure wake losses at different distances from profile trailing edge were required. The selected interface with wind tunnel test section was the arc sector model support system, already equipped with passages for tubes routing to the plenum, and an easy and quick installation was required to enhance productivity. This work presents the process leading to technical specifications, as well as system design and some design details. Some test results are presented, that show how requirements have been fulfilled.