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Validity of Miles Equation in Predicting Propellant Slosh Damping in Baffled Tanks at Variable Slosh AmplitudeDetermination of slosh damping is a very challenging task as there is no analytical solution. The damping physics involves the vorticity dissipation which requires the full solution of the nonlinear Navier-Stokes equations. As a result, previous investigations were mainly carried out by extensive experiments. A systematical study is needed to understand the damping physics of baffled tanks, to identify the difference between the empirical Miles equation and experimental measurements, and to develop new semi-empirical relations to better represent the real damping physics. The approach of this study is to use Computational Fluid Dynamics (CFD) technology to shed light on the damping mechanisms of a baffled tank. First, a 1-D Navier-Stokes equation representing different length scales and time scales in the baffle damping physics is developed and analyzed. Loci-STREAM-VOF, a well validated CFD solver developed at NASA MSFC, is applied to study the vorticity field around a baffle and around the fluid-gas interface to highlight the dissipation mechanisms at different slosh amplitudes. Previous measurement data is then used to validate the CFD damping results. The study found several critical parameters controlling fluid damping from a baffle: local slosh amplitude to baffle thickness (A/t), surface liquid depth to tank radius (d/R), local slosh amplitude to baffle width (A/W); and non-dimensional slosh frequency. The simulation highlights three significant damping regimes where different mechanisms dominate. The study proves that the previously found discrepancies between Miles equation and experimental measurement are not due to the measurement scatter, but rather due to different damping mechanisms at various slosh amplitudes. The limitations on the use of Miles equation are discussed based on the flow regime.
Document ID
20180000881
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Yang, H. Q.
(CFD Research Corp. Huntsville, AL, United States)
West, Jeff
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
January 31, 2018
Publication Date
January 8, 2018
Subject Category
Fluid Mechanics And Thermodynamics
Propellants And Fuels
Report/Patent Number
M17-6064
Meeting Information
Meeting: AIAA SciTech 2018
Location: Kissimmee, FL
Country: United States
Start Date: January 8, 2018
End Date: January 12, 2018
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
CONTRACT_GRANT: NNM12AA41C
OTHER: ES.16.05.R42.SSEI.ISQ.0000
Distribution Limits
Public
Copyright
Public Use Permitted.
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