Numerical Modeling of Air Cushion Vehicle Flexible Seals
Cole, Robert Edward
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Air cushion vehicle flexible seals operate in a complex and chaotic environment dominated by fluid-structure interaction. An efficient means to explore interdependencies between various governing parameters that affect performance is through high fidelity numerical simulation. As previous numerical efforts have employed separate iterative partitioned solvers, or have implemented simplified physics, the approaches have been complex, computationally expensive, or of limited utility. This research effort performs numerical simulations to verify and validate the commercial multi-physics tool STAR-CCM+ as a stand-alone partitioned approach for fluid-structure interaction problems with or without a free surface. A dimensional analysis is first conducted to identify potential non-dimensional forms of parameters related to seal resistance. Then, an implicit, Reynolds-averaged Navier-Stokes finite volume fluid solver is coupled to an implicit, nonlinear finite element structural solver to successfully replicate benchmark results for an elastic beam in unsteady laminar flow. To validate the implementation as a seal parameter exploratory tool, a planer bow seal model is developed and results are obtained for various cushion pressures and inflow speeds. Previous numerical and experimental results for deflection and resistance are compared, showing good agreement. An uncertainty analysis for inflow velocity reveals an inversely proportional resistance dependency. Using Abaqus/Explicit, methodologies are also developed for a two-way, loosely coupled explicit approach to large deformation fluid-structure interaction problems, with and without a free surface. Following numerous verification and validation problems, Abaqus is ultimately abandoned due to the inability to converge the fluid pressure field and achieve steady state. This work is a stepping stone for future researchers having interests in ACV seal design and other large deformation, fluid-structure interaction problems. By modeling all necessary physics within a verified and validated stand-alone approach, a designer's ability to comprehensively investigate seal geometries and interactions has never been more promising.
- Doctoral Dissertations