An engineering modification of the blade element momentum combination applicable in vertical descent flight :fundamentals and validation

Cuerva Tejero, Alvaro and Sanz Andres, Angel Pedro and Meseguer Ruiz, José and Espino Granado, Jose Luis (2006). An engineering modification of the blade element momentum combination applicable in vertical descent flight :fundamentals and validation. "Journal of the American Helicopter Society", v. 51 (n. 4); pp. 349-354. ISSN 2161-6027. https://doi.org/10.4050/JAHS.51.349.

Description

Title: An engineering modification of the blade element momentum combination applicable in vertical descent flight :fundamentals and validation
Author/s:
  • Cuerva Tejero, Alvaro
  • Sanz Andres, Angel Pedro
  • Meseguer Ruiz, José
  • Espino Granado, Jose Luis
Item Type: Article
Título de Revista/Publicación: Journal of the American Helicopter Society
Date: October 2006
ISSN: 2161-6027
Volume: 51
Subjects:
Faculty: Instituto de Microgravedad Ignacio Da Riva (UPM)
Department: Aeronaves y Vehículos Espaciales
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

An engineering modification of blade element/momentum theory is applied to describe the vertical autorotation of helicopter rotors. A full non‐linear aerodynamic model is considered for the airfoils, taking into account the dependence of lift and drag coefficients on both the angle of attack and the Reynolds number. The proposed model, which has been validated in previous work, has allowed the identification of different autorotation modes, which depend on the descent velocity and the twist of the rotor blades. These modes present different radial distributions of driven and driving blade regions, as well as different radial upwash/downwash patterns. The number of blade sections with zero tangential force, the existence of a downwash region in the rotor disk, the stability of the autorotation state, and the overall rotor autorotation efficiency, are all analyzed in terms of the flight velocity and the characteristics of the rotor. It is shown that, in vertical autorotation, larger blade twist leads to smaller values of descent velocity for a given thrust generated by the rotor in the autorotational state.

More information

Item ID: 40115
DC Identifier: http://oa.upm.es/40115/
OAI Identifier: oai:oa.upm.es:40115
DOI: 10.4050/JAHS.51.349
Official URL: https://vtol.org/publications/journal-of-ahs/journal-guidelines
Deposited by: Biblioteca ETSI Aeronauticos
Deposited on: 18 May 2016 12:33
Last Modified: 13 Jun 2016 09:27
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