Experimental Validation of an Ultrasonic Absorption Testing Apparatus for Hypersonic Flow Control Materials

To characterize the performance of ultrasonically absorptive flow control materials for hypersonic flight, a pressure controlled and temperature sensing bench-test was developed by the author under Office of Naval Research SBIR Contract #N6833519C0312 awarded in 2019. This testing apparatus is capable of experimentally determining the absorption power coefficient of arbitrary materials using a solid non-porous material as a reference. The testing methodology presented by the author was validated against a theoretical model. It was found that to accurately estimate the acoustic absorption coefficient of materials at high frequencies, temperature and humidity measurements are equally as critical as pressure measurements to ensure that the properties of the acoustic medium and electrical components are accounted for.