Measurement and Assessment of Flow Quality in Wind Tunnels

New wind tunnel flow quality test and analysis procedures have been developed and will be used to establish standardized turbulent flow quality measurement techniques and data reduction procedures for future flow quality studies in the National Transonic Wind Tunnel (NTF) and other Aeronautics Test Program (ATP) facilities. To date, few measurements have been made of the characteristics of freestream turbulence in transonic wind tunnels, and details of the amplitude and spectra of freestream velocity and pressure fluctuations is lacking. Consequently, there is an urgent need for in-situ measurements to determine flow quality and the performance of turbulence and noise suppression devices. This information is required if we are to accurately assess and characterize ground test facility performance. To meet these challenges, a unique research program is proposed to clarify and alleviate the aerodynamic problems associated with adverse wind tunnel flow quality. It combines innovative advances in data base assessment and management, and new approaches to turbulence instrumentation and analysis. Standardized turbulence measurement techniques and data analysis procedures will be established and used to document the flow quality in our major test facilities.