Aeroelastic Modeling of a Nozzle Startup Transient
Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading to structural damages if structural strengthening measures were not taken. The modeling picture is incomplete without the capability to address the two-way responses between the structure and fluid. The objective of this study is to develop a tightly coupled aeroelastic modeling algorithm by implementing the necessary structural dynamics component into an anchored computational fluid dynamics methodology. The computational fluid dynamics component is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, while the computational structural dynamics component is developed under the framework of modal analysis. Transient aeroelastic nozzle startup analyses at sea level were performed, and the computed transient nozzle fluid-structure interaction physics presented,
Parallel Interpolation in FSI Problems Using Radial Basis Functions and Problem Size Reduction ?
In strongly coupled fluid-structure interaction simulations, the fluid dynamics and solid dynamics problems are solved independently on their own meshes. Therefore, it becomes necessary to interpolate physical properties (pressure, displacement) across two meshes. In this work, we propose to accelerate the interpolation process by the method of radial basis functions using the matrix-free solution of the equation system on a GPU.
A unified Navier-Stokes flowfield and performance analysis of liquid rocket engines
In an effort to improve the current composite solutions in the design and analysis of liquid propulsive engines, a computational fluid dynamics (CFD) model capable of calculating the reacting flows from the combustion chamber, through the nozzle to the external plume, is developed. Flowfields of a conical nozzle and the Space Shuttle main engine (SSME) fired at sea level are investigated. The CFD model, FDNS (finite difference NavierStokes), is a pressure-based, viscous, ideal gas/real gas, reactive flow code. An equilibrium chemistry algorithm is employed using the point implicit method. A conical nozzle with the same expansion ratio as the SSME nozzle is computed to study the shock formation in both the internal and external flowfields. The bell-shaped SSME nozzle is run at 100% power level at various flow conditions. The computed flow solutions and nozzle thrust performance are in good agreement with those of other standard codes and engine hot fire test data.