Faculté des Sciences appliquées
Faculté des Sciences appliquées

Travail de fin d'études et stage[BR]- Travail de fin d'études : Blade Element Momentum Theory extension for the modelisation of a contra-rotating rotors drone[BR]- Stage d'insertion professionnelle

Le, Johan ULiège
Promotor(s) : Hillewaert, Koen ULiège
Date of defense : 27-Jun-2022/28-Jun-2022 • Permalink :
Title : Travail de fin d'études et stage[BR]- Travail de fin d'études : Blade Element Momentum Theory extension for the modelisation of a contra-rotating rotors drone[BR]- Stage d'insertion professionnelle
Translated title : [fr] Extension de la "Blade Element Momentum Theory" pour la modélisation d'un drone à rotors contra-rotatifs
Author : Le, Johan ULiège
Date of defense  : 27-Jun-2022/28-Jun-2022
Advisor(s) : Hillewaert, Koen ULiège
Committee's member(s) : Greffe, Christophe 
Dimitriadis, Grigorios ULiège
Language : English
Number of pages : 83
Keywords : [en] BEMT
[en] Coaxial
[en] performances
[en] validation
[en] experiments
[en] simulations
Discipline(s) : Engineering, computing & technology > Aerospace & aeronautics engineering
Institution(s) : Université de Liège, Liège, Belgique
Degree: Master : ingénieur civil mécanicien, à finalité spécialisée en mécatronique
Faculty: Master thesis of the Faculté des Sciences appliquées


[en] This thesis focuses on the study, the development and the implementation of a
model for coaxial, contra-rotating rotors based on the Blade Element Momentum
Theory (BEMT ) in order to predict the performances of an operating coaxial drone
and to optimise its configuration such that it minimises the power consumed.

The implemented BEMT (commonly used in the development of turbomachinery)
describes completely the airflow through the rotor from the far upstream to the far
downstream by providing the velocity triangles and the local aerodynamical variables in the rotor surrounding. It significantly improves the understanding of the
variation of the rotor performances and how the tuning of the control parameters
such as the rotor rotation speed or the blade collective pitch angle play an essential
role in the optimisation of the coaxial drone rotor.

At first, the simulations results are validated for the isolated rotor case by contrasting them with benchmark experiments from the literature and with experimental
measurements realised on a drone test bench and provided by the industrial promoter of this thesis. The outcomes shows a good agreement with the actual drone
operation and even better when considering additional correction factors such
as the Prandtl loss factor or the induced power factor. In fact, the performances
graphics are depicted and analysed. These consists in the variations of thrust, the
mechanical power with respect to the rotor rotation speed and the power loading
evolution as function of a given thrust. The thrust and power predictions revealed
a favourable adaption to the tuning of the collective pitch angle accounting for a
one-degree of accuracy on the angle. While the power loading (and thus the rotor
propulsive efficiency) increases with the blade length. Furthermore, it is demonstrated that an increase of the blade collective pitch angle from 2° to 3° is required
in order to enhance the matching between the predictions and the experimental
measurements. Since the one-degree of accuracy on the blade collective pitch angle
can not explained this deviation, it is supposed that the error comes from an issue
in the fixing mechanism of the blade.

Subsequently, the experimental operating data measured on a drone prototype
are used to analyse and to validate the predictions of the coaxial model. The simuilations outcomes allows to feature the interest in the upper rotor wake contraction
application and especially, the consideration of the rotors axial separation distance
in the model implementation. As a matter of fact, the consideration of the wake
constriction of the upper rotor slipstream shows a reduction of 10% to 20% of the
relative errors measured on the lower rotor mechanical power predictions with
respect to the measurements data. Nonetheless, erroneous predictions of the mechanical power at the upper rotor are still indicated. It is supposed that it stems
from the non-consideration of the adverse influence of the lower on the upper rotor.



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  • Le, Johan ULiège Université de Liège > Master ing. civ. méc., à fin.


Committee's member(s)

  • Greffe, Christophe Generix
  • Dimitriadis, Grigorios ULiège Université de Liège - ULiège > Département d'aérospatiale et mécanique > Interactions Fluide-Structure - Aérodynamique expérimentale
    ORBi View his publications on ORBi
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  • Total number of downloads 12

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