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Simulation of Ground Winds Time Series for the NASA Crew Launch Vehicle (CLV)Simulation of wind time series based on power spectrum density (PSD) and spectral coherence models for ground wind turbulence is described. The wind models, originally developed for the Shuttle program, are based on wind measurements at the NASA 150-m meteorological tower at Cape Canaveral, FL. The current application is for the design and/or protection of the CLV from wind effects during on-pad exposure during periods from as long as days prior to launch, to seconds or minutes just prior to launch and seconds after launch. The evaluation of vehicle response to wind will influence the design and operation of constraint systems for support of the on-pad vehicle. Longitudinal and lateral wind component time series are simulated at critical vehicle locations. The PSD model for wind turbulence is a function of mean wind speed, elevation and temporal frequency. Integration of the PSD equation over a selected frequency range yields the variance of the time series to be simulated. The square root of the PSD defines a low-pass filter that is applied to adjust the components of the Fast Fourier Transform (FFT) of Gaussian white noise. The first simulated time series near the top of the launch vehicle is the inverse transform of the adjusted FFT. Simulation of the wind component time series at the nearest adjacent location (and all other succeeding next nearest locations) is based on a model for the coherence between winds at two locations as a function of frequency and separation distance, where the adjacent locations are separated vertically and/or horizontally. The coherence function is used to calculate a coherence weighted FFT of the wind at the next nearest location, given the FFT of the simulated time series at the previous location and the essentially incoherent FFT of the wind at the selected location derived a priori from the PSD model. The simulated time series at each adjacent location is the inverse Fourier transform of the coherence weighted FFT. For a selected design case, the equations, the process and the simulated time series at multiple vehicle stations are presented.
Document ID
20080014167
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Adelfang, Stanley I.
(Stanley Associates, Inc. United States)
Date Acquired
August 24, 2013
Publication Date
January 20, 2008
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: 12th Conference on Aviation, Range and Aerospace Meteorology Affects of the Atmosphere on the Performance, Design and Operation of Aerospace Systems
Location: New Orleans, LA
Country: United States
Start Date: January 20, 2008
End Date: January 24, 2008
Funding Number(s)
CONTRACT_GRANT: NNM04AA02C
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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