Numerical investigation on the use of multi-element blades in vertical-axis wind turbines

Bah, Elhadji Alpha Amadou

Title:

Numerical investigation on the use of multi-element blades in vertical-axis wind turbines

dc.contributor.advisor	Sankar, Lakshmi N.
dc.contributor.advisor	Jagoda, Jechiel I.
dc.contributor.author	Bah, Elhadji Alpha Amadou
dc.contributor.committeeMember	Costello, Mark
dc.contributor.committeeMember	Schrage, Daniel
dc.contributor.committeeMember	Shelton, Samuel
dc.contributor.department	Aerospace Engineering
dc.date.accessioned	2015-06-08T18:20:41Z
dc.date.available	2015-06-08T18:20:41Z
dc.date.created	2015-05
dc.date.issued	2015-01-12
dc.date.submitted	May 2015
dc.date.updated	2015-06-08T18:20:41Z
dc.description.abstract	The interest in sustainable forms of energy is being driven by the anticipated scarcity of traditional fossil fuels over the coming decades. There is also a growing concern about the effects of fossil fuel emissions on human health and the environment. Many sources of renewable energy are being researched and implemented for power production. In particular, wind power generation by horizontal- and vertical-axis wind turbines is very popular. Vertical-axis wind turbines (VAWTs) have a relative construction simplicity compared to horizontal-axis wind turbines (HAWTs). However, VAWTs present specific challenges that may hinder their performance. For instance, they are strongly affected by dynamic stall. A significant part of the kinetic energy contained in the oncoming wind is lost in swirl and vortices. As a result, VAWTs have lower power production compared to HAWTs. First, the present work is aimed at the study of the aerodynamics of straight-bladed VAWTs (SB-VAWTs). Empirical calculations are conducted in a preliminary work. Then a two-dimensional double multiple streamtube (DMST) approach supported by a two-dimensional numerical study is implemented. The dynamic stall and aerodynamic performance of the rotor are investigated. A VAWT-fitted dynamic stall model is implemented. Computational fluid dynamics (CFD) simulations are conducted to serve as reference for the DMST calculations. This three-pronged approach allows us to efficiently explore multiple configurations. The dynamic stall phenomenon is identified as a primary cause of performance loss. The results in this section validate the DMST model as a good replacement for CFD analysis in early phase design provided that a good dynamic stall model is used. After having identify the primary cause of performance loss, the goal is to investigate the use to dual-element blades for alleviating the effect of dynamic stall, thereby improving the performance of the rotor. The desirable airfoil characteristics are defined and a parametric analysis conducted. In the present study the parameters consists of the size of the blade elements, the space between them, and their relative orientation. The performance of the rotor is calculated and compared to the baseline. The results highlight the preeminence of the two-element configuration over the single-element provided that the adequate parametric study is conducted beforehand. A performance enhancement is obtained over a large range of tip speed ratios. The starting characteristics and the operation stability are also improved. Finally, an economic analysis is conducted to determine the cost of energy and thus the financial viability of such a project. The Great Coast of Senegal is selected as site of operation. The energy need and sources of this region are presented along with its wind energy potential. The cost evaluation shows the economic viability by comparing the cost of energy to the current energy market prices.
dc.description.degree	Ph.D.
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/1853/53501
dc.language.iso	en_US
dc.publisher	Georgia Institute of Technology
dc.subject	CFD
dc.subject	VAWT
dc.subject	DMST
dc.subject	Dynamic stall
dc.subject	Multi-elements
dc.subject	Financial viability
dc.title	Numerical investigation on the use of multi-element blades in vertical-axis wind turbines
dc.type	Text
dc.type.genre	Dissertation
dspace.entity.type	Publication
local.contributor.advisor	Sankar, Lakshmi N.
local.contributor.advisor	Jagoda, Jechiel I.
local.contributor.corporatename	College of Engineering
local.contributor.corporatename	Daniel Guggenheim School of Aerospace Engineering
local.relation.ispartofseries	Doctor of Philosophy with a Major in Aerospace Engineering
relation.isAdvisorOfPublication	22a68276-4f0c-499c-9dd9-931e34bf40a8
relation.isAdvisorOfPublication	82d8814b-a147-40a3-908d-cb7a4766cdbe
relation.isOrgUnitOfPublication	7c022d60-21d5-497c-b552-95e489a06569
relation.isOrgUnitOfPublication	a348b767-ea7e-4789-af1f-1f1d5925fb65
relation.isSeriesOfPublication	f6a932db-1cde-43b5-bcab-bf573da55ed6
thesis.degree.level	Doctoral