Hypersonic Dimensional Scanning System

Ablative coatings for hypersonics are tested at facilities such as the AEDC Range G and the Holloman High Speed Test Track. A test article is accelerated to velocity up to 18,000 ft/s in a relevant atmosphere and travels up to 10,000 ft. It is important to measure the coating erosion at multiple discrete points along the trajectory to characterize non-linear ablation response. Existing measurement techniques employ ordinary high speed photography. Evaluation of the resulting 2-D images to infer 3-D ablation is challenging and imprecise, particularly considering the refractive errors introduced by the bow shock. We have developed a novel imaging system that freezes motion even at peak velocities, directly measures the 3-D geometry of the test article front surface, and corrects for refractive errors induced by shock waves in the flow field. The result of the measurement is a 3-D point cloud with .001″ resolution that can be directly compared between successive measurements to compute ablation rates. We will implement this imaging system at the Range G facility and validate its performance in a series of hypersonic tests.