Measurements Supporting the 2014 First Sonic Boom Workshop Prediction Cases

摘要

Measurement of new, much quieter, shaped sonic booms revealed that tiny flow field variations in supersonic wind tunnel test sections were enough to distort these signatures' pressures by 20-50%. A "Spatial Averaging" technique was developed, whereby at least twenty measurements are taken while translating a model 12-16 inches (30-41cm). The average of the measurements reduced these flow field distortions almost 2 orders-of-magnitude, yielding sufficient validation precision and repeatability for these quiet shaped sonic booms. An AIAA Sonic Boom Prediction Workshop was held in January 2014 to assess the state of the art of prediction. The geometries chosen as prediction cases for the workshop had also been measured using this spatial averaging technique. This paper documents the measurements for prediction validation.