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CNAA / Theses / 2022 / May /

Constructive and functional optimization of helical vertical axis wind rotors with the aim of increasing the wind energy conversion efficiency

Author: Rabei Ivan
Degree:doctor of engineering
Speciality: 05.02.08 - Manufacturing engineering
Scientific adviser: Rodion Ciupercă
doctor, associate professor (docent)
Institution: Technical University of Moldova


The thesis was presented on the 26 May, 2022
Approved by NCAA on the 30 September, 2022


Adobe PDF document1.32 Mb / in romanian


CZU 621.833.6

Adobe PDF document 10.64 Mb / in romanian
196 pages


Vertical axis wind turbine; wind rotor, helical blades; straight blades; airfoil; J-type blades; opening at the blade’s trailing edge; aspect ratio; drag type blades, CFD, efficiency; circular economy; plastic blades; HDPE


Thesis content: The thesis consists of the introduction, four main chapters, conclusions and recommendations, 152 references, 15 appendixes, 144 text pages including 136 figures and 17 tables. The thesis results have been published in 1 monography, 8 scientific papers, including 3 sole authored. 2 patents were obtained and 1 patent application was filled.

Purpose of the paper: increasing the conversion efficiency of the helically bladed vertical axis wind turbines by optimizing the geometric parameters. Research objectives: research of the recommended airfoils for vertical axis wind turbines; determining the influence of the blade’s helical angle on the rotor’s conversion efficiency; determining the influence of the opened blades (J-type) on the rotor conversion efficiency; determining the optimum rotor aspect ratio; CFD analysis of the airfoils; identifying the materials and elaboration of manufacturing technology for wind rotor blades taking into account the circular economy principles; elaboration of a design algorithm for the vertical axis wind turbines.

Scientific novelty and originality consist of: the experimental confirmation of the asymmetrical airfoils potential, particularly FX 63-137, as well as the potential of the opened blades (J type blades); identifying the interdependence between the helical angle and the chosen airfoil. Here it can be asserted that the helical angle can be an aerodynamically efficient configuration compared to straight blades but not for airfoils; establishing the optimal rotor aspect ratio; developing the manufacturing steps necessary for the fabrication of the vertical axis wind turbine blades from HDPE plastic; elaboration of an algorithm that facilitates the vertical axis wind turbines design.

The obtained result that contributes to solving an important scientific problem consists in the scientific substantiation of the vertical axis wind rotor parameters, which led to the elaboration of recommendations necessary at the designing and fabrication stages, in order to ensure higher energy conversion efficiency.

Theoretical implication: elaboration of the CAD model and CAE analysis of vertical axis rotors; CFD analysis of the airfoils; elaboration of an algorithm for vertical axis wind rotors design.

Practical value: the paper comes with recommendations necessary at the designing stage of the vertical axis wind rotors. The recommendations refer to the use of the asymmetrical airfoils, particularly FX 63-137 oriented with the concave side out; the use of the J type blades; in case of choosing helical blades, it is necessary to identify the proper airfoil which capitalizes on this specific blade shape. The HDPE plastic can be considered for manufacturing low power vertical axis wind turbine blades.

Application of the scientific results: The research results were used for teaching for the graduate program. A textbook and a laboratory stand for learning and research purposes was developed. This allows the investigation of the influence of several geometrical parameters of the vertical axis wind rotor on the conversion efficiency using the wind tunnel in the Aerodynamics