Using Ultrasound and the Extended Kalman Filter for Characterizing Aerothermodynamic Environments

• Published in: AIAA journal 2013-10, Vol.51 (10), p.2410-2419
• Main Authors: Myers, Michael R, Jorge, Ariosto B, Yuhas, Don E, Walker, D. Greg
• Format: Article
• Language: English
• Subjects: Aerodynamics; Aerospace engineering; Air transportation and traffic; Applied sciences; Boundary layer transition; Computational fluid dynamics; Exact sciences and technology; Extended Kalman filter; Flight control; Ground, air and sea transportation, marine construction; Heat flux; Heating; Kalman filters; Laminar flow; Measurement methods; Metal plates; Parameter estimation; Sensor arrays; Systems design; Thermal protection; Throttles; Turbulent flow; Ultrasonic imaging
• ISSN: 0001-1452; 1533-385X
• DOI: 10.2514/1.J052313

Characterizing aerothermodynamic environments represents a significant challenge to aircraft operations. Hypersonic boundary-layer structure including transitions from laminar flow to turbulent flow is important to air vehicle design, thermal protection system design, and air vehicle in-flight control. Because the transition region cannot be observed directly, an inverse procedure must be formulated that relates transition region characteristics with parameters that can be measured. We propose a novel measurement system that leverages the hypersonic body-surface heating profile to locate the boundary-layer transition region. In this work, we focus on ultrasonic sensing as the measurement strategy, a three-dimensional conduction solution, and the extended Kalman filter for the inverse procedure. Development of the proposed measurement method is accomplished using simple, controlled experiments involving a high-heat flux step source on a large flat metal plate. Although the heating profile of the step source used in this work is somewhat similar in profile to the hypersonic transition region heating profile, the transition region may exhibit smaller gradients, nonuniform heating before and after the transition, and irregular shapes. Heating-source localization results and convergence behavior are compared for the extended Kalman filter and simulated one-way ultrasonic pulse measurements. Sensor-array pattern experiment results are presented for the sensor array. The extended Kalman filter was found to be robust and appropriate for applications where the user has control over some aspect of the environment that affects the parameters being estimated (e.g., throttle, attitude controls, etc.).