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Title: User's Guide to BModes (Software for Computing Rotating Beam-Coupled Modes)

Technical Report ·
DOI:https://doi.org/10.2172/861489· OSTI ID:861489

This guide explains data preparation and execution with BModes, a finite-element code that provides dynamically coupled modes for a beam. The beam can be a rotating or non-rotating rotor blade or a tower, and it can have arbitrary distribution of structural properties and geometry along its length. A coupled mode implies presence of coupled flexural, axial, and torsion motions in a natural mode of vibration. Knowledge of flap-lag-torsion-axial coupled modes is crucial to several applications. Examples are: accurate modeling of major flexible components for modal-based aeroelastic codes such as FAST (Fatigue, Aerodynamics, Structures, and Turbulence), validation of flexible component models using experimental data, modal-based fatigue analysis, and interpretation of aeroelastic-stability behavior of turbines. Our plan is to eventually integrate BModes with FAST to provide tower and blade modes as rotor speed and blade pitch control settings change during a simulation. This guide provides step-by-step instructions on how to prepare input files (specify blade geometry, section properties, and finite-element discretization), how to execute the code, and how to interpret the outputs.

Research Organization:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC36-99-GO10337
OSTI ID:
861489
Report Number(s):
NREL/TP-500-39133; TRN: US200601%%875
Country of Publication:
United States
Language:
English