Design of an Instrumentation System for a Boundary Layer Transition Wing Glove Experiment

Laminar flow control holds major promise for increasing aircraft efficiency and increasing laminar flow over aerodynamic surfaces could decrease drag by up to 30 percent. The Flight Research Lab at Texas A&M University has studied laminar flow over a wing with 30 degrees of leading edge sweep with Discrete Roughness Elements (DREs) installed and has indicated that DREs can be used to increase laminar flow at Reynolds numbers up to 7.5 million at Mach 0.3. A new project, termed SARGE, has been commissioned in conjunction with NASA for studying DREs on a swept wing glove at conditions relevant to jet transports. The SARGE project must have an instrumentation system capable of accurately measuring flow conditions and transition location on the suction side of the glove. Infrared (IR) thermography has been selected as the primary transition detection tool. A heat transfer analysis has shown that solar radiation will warm the surface of the glove above the adiabatic wall temperature and therefore the laminar region will appear to be warmer. The FLIR SC8000 IR camera has been selected for this application due to its ability to produce high-resolution images in the appropriate IR band. High quality air data is also required for the experiment. A five-hole probe will be used to measure flow angle and velocity near the glove. This instrument will provide meanflow conditions due to its limited frequency response. High quality pressure transducers coupled with careful probe calibration will allow for differential measurements to be made with an uncertainty of +/- 0.03 degrees. Static pressure ports and high frequency response Kulite transducers will also be employed. Hotfilm sensors will be used to verify the state of the boundary layer on the glove through spectral analysis. A unique hotfilm array has been proposed that will enable the measurement of traveling wave vectors through a spectral technique. An experiment on the Flight Research Lab's Cessna O-2 to investigate the veracity of this technique has also been suggested. Thermocouples will also be installed on the glove's surface to monitor temperatures and verify transition location. The layout of the hotfilms and thermocouples is also detailed