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Space Launch System (SLS) LOX Damper

The LOX damper is a fluid-coupled damping device developed to mitigate thrust-induced structural vibrations in the Ares I, SLS, and other launch vehicles. The device works by using the weight of the LOX (or other propellant) in the propellant tank in conjuction with a compressible degree of freedom within the fluid provided by the moving damper surface. The coupling between the fluid motion and the motion of the damper compressible degree of freedom can then be used to control the overall level of vibration in the tank at a given frequency.

DCI personnel are a key part of the NASA/MSFC LOX damper team and have been heavily involved in the testing, analysis, and simulation activities associed with the project. DCI personnel were the first to derive the coupled fluid-structure dynamic equations that describe the physics involved and which have been used as the theoretical basis for almost all damper configurations. In addition, DCI was the first to show that the LOX dampers could be modeled by the finite element method. DCI personnel developed DCI-HYDRO, a specialized hydroelastic code that can model fluid propellant in a flexible tank including the effects of fluid slosh and devices such as the LOX damper. Most of the damper test configurations were successfully modeled using this approach. Numerous LOX damper design configurations for Ares and SLS have also been modeled and integrated into the vehicle dynamic finite element models. These dynamic models were then used by DCI to evaluate the vibration mitigation effects of the damper by running many different vehicle dynamic simulations. Currently, DCI is continuing itís support for the fluid damper team activities investigating the effectiveness of the damper for additional uses such as mitigation of lateral oscillations, slosh damping, and potential commercial applications.

Cylindrical Tank Propellant Slosh Modes as Calculated by DCI-HYDRO Code

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