Damping the fluctuating behaviour and improving the convergence rate of the axial induction factor in the BEMT-based rotor aerodynamic codes

Alireza Maheri*, Siamak Noroozi, Chris Toomer, John Vinney

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

Abstract

A common problem in the rotor aerodynamic codes which are based on the Blade Element Momentum Theory is the fluctuating behaviour of the axial induction factor in its iteration loop. These fluctuations are due to periodically switching of the loading state between light and heavy. Normally in such situations, after a predefined maximum number of iterations, the iteration process stops and the program skips that blade segment. This impacts both the accuracy of the predicted results and the code performance. This paper presents a method to avoid this behaviour by using a relaxation factor applicable in the iteration process. By this, no matter how high the amplitudes of the fluctuations, using a proper relaxation factor leads to a converged solution. This method also uses the first few iterated values to predict the neighbourhood of the final converged axial induction factor. This can be used to accelerate the convergence process. It has been shown that selection of a proper relaxation factor together with a simple modification to the predicted axial induction factor after a few iterations highly improves the convergence rate.

Original languageEnglish
Title of host publicationEuropean Wind Energy Conference and Exhibition 2006, EWEC 2006
Pages1176-1179
Number of pages4
Volume2
Publication statusPublished - 2006
EventEuropean Wind Energy Conference and Exhibition 2006, EWEC 2006 - Athens, Greece
Duration: 27 Feb 20062 Mar 2006

Conference

ConferenceEuropean Wind Energy Conference and Exhibition 2006, EWEC 2006
CountryGreece
CityAthens
Period27/02/062/03/06

Keywords

  • BEMT
  • Relaxation factor
  • Rotor aerodynamic
  • Wind turbine simulation

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