A LASER BASED TRANSITION DETECTOR

ONE OF THE LARGEST SOURCES OF UNCERTAINTY IN PROPOSED HYPERSONIC TESTING OF THE NATIONAL AEROSPACE PLANE WILL BE THE MEASUREMENT OF THE EXTENT OF LAMINAR FLOW ON WIND TUNNELTEST MODELS WITH FREE AND FORCED TRANSITION. IN AN ATTEMPT TO ALLEVIATE THIS PROBLEM, A NOVEL CONCEPT FOR THE REMOTE DETECTION OF BOUNDARY-LAYER TRANSITION HAS BEEN PROPOSED. THIS LASER-BASED TURBULENT BURST DETECTOR WILL ENABLE NON-INTRUSIVE, MICROSCOPIC STUDIES OF THE ONSET AND EXTENT OF TRANSITION BY RAPIDLY SCANNING WIND TUNNEL MODEL BOUNDARYLAYERS. THE POTENTIAL OF THIS NEW INSTRUMENT WILL BE IN THECAPABILITY IT PROVIDES FOR THE RAPID MAPPING OF IRREGULAR TRANSITION PATTERNS WHICH OFTEN OCCUR ON COMPLICATED WIND-TUNNEL TEST MODELS. IT WILL ALSO REPLACE IMPRACTICALLYLARGE NUMBERS OF SURFACE GAGES WHICH WOULD BE REQUIRED FOR TRANSITION MEASUREMENT AND SO SUBSTANTIALLY REDUCE MODEL CONSTRUCTION COSTS AND WIND-TUNNEL TEST TIME.