Rotor Blade Flap-Lag Stability and Response in Forward Flight in Turbulent Flows
Shiau, Ting-Nung Bernard
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/70630
Description
Title
Rotor Blade Flap-Lag Stability and Response in Forward Flight in Turbulent Flows
Author(s)
Shiau, Ting-Nung Bernard
Issue Date
1984
Department of Study
Aeronautical and Astronautical Engineering
Discipline
Aeronautical and Astronautical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Aerospace
Abstract
The effect of random air turbulence on the coupled flap-lag motion of a helicopter rotor blade in forward flight is investigated. By assuming white noise turbulence and applying a special case of the stochastic averaging procedure, equations are developed which describe the stochastic first and second moments of the perturbations in flap and lead-lag angles due to turbulence.
Numerical results for stability in forward flight illustrate that turbulence exhibits a stabilizing effect, compared to the deterministic (no turbulence) case. Results for the steady-state responses of the perturbations in forward flight indicate that the average responses of the perturbations in forward flight indicate that the average response of the blade is not significantly affected by turbulence. In contrast, the random fluctuations away from the average response exhibit significantly large values due to the effects of turbulence. The effects of various blade parameters on the steady-state response are also investigated.
The stability of multibladed rotors in the presence of turbulence is investigated using the example of a three-bladed rotor. The constant coefficient approximation using multiblade coordinates is shown to be accurate for moderate advance ratio in the case of a trimmed rotor. For an untrimmed rotor the approximation is less accurate and provides very conservative stability boundaries.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
