Photogrammetry Measurements of Blunt Body Dynamics in a Supersonic Wind Tunnel

This paper presents a novel and robust photogrammetry method to measure rigid-body dynamics in a high-speed wind tunnel. A faceted blunt model is free to rotate in roll, pitch and yaw in response to the freestream flow (M = 2) by means of a spherical air bearing. Four synchronised high-speed cameras capture the model from different angles, and the unique coded targets printed on the model’s surface are reconstructed as points in 3D space, achieving accuracy within 1 ^◦ for both static and dynamic measurements. The Kabsch algorithm is used to find the optimal rotation between two point clouds, hence allowing reconstruction of the angular motion over the entire run. The experiments reveal a precessional instability previously reported only for slender bodies at hypersonic Mach numbers. The method shows promise for free-oscillation tests in high-speed ground facilities, with advantages over conventional IMU-based approaches such as non-invasivity, direct measurement of the model’s orientation, and higher sampling rates.