The role of structural acoustics in the space shuttle flowliner crack investigation

Abstract

During normal inspection of the Space Shuttle main propulsion fuel line system small cracks were identified in a slotted flowliner just upstream of the main propulsion engines. The cause is believed to be resonance excited by pressure fluctuations originating from the downstream fuel pump. This presentation highlights the analyses that were performed to characterize the structural acoustic environment surrounding the flowliner during waterflow and liquid hydrogen laboratory experiments, as well as in-flight conditions. Analyses employed a combination of analytical and finite-element methods to model fluid structure interaction and inverse methods to reconstruct equivalent acoustic sources representative of the fuel pump. Numerical results will be presented that compare experimental strain and pressure data with theoretical counterparts. Implications will be drawn regarding the applicability of the theory to the actual shuttle fuel line system. [Work was sponsored by NASA Marshall Flight Center.]