東華大學圖書館 |

Optimal Aerodynamic Design of Ducted Wind Turbines.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Optimal Aerodynamic Design of Ducted Wind Turbines./
作者:	Bagheri-Sadeghi, Nojan.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	78 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-04, Section: B.
Contained By:	Dissertations Abstracts International83-04B.
標題:	Mechanical engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28716760
ISBN:	9798460408436

Optimal Aerodynamic Design of Ducted Wind Turbines.
Bagheri-Sadeghi, Nojan.

Optimal Aerodynamic Design of Ducted Wind Turbines. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 78 p.

Source: Dissertations Abstracts International, Volume: 83-04, Section: B.

Thesis (Ph.D.)--Clarkson University, 2021.

This item must not be sold to any third party vendors.

The presence of a duct around a wind turbine can significantly improve its power output by increasing the mass flow rate through the rotor. This thesis aims at determining the optimal aerodynamic design of ducted wind turbines for either maximal power per rotor area, CP, or maximal power per total frontal device area, CP,total. Additionally, a comparison of the pwake recovery rate of ducted and open-rotor wind turbines is carried out with the goal of determining the suitability of using ducted wind turbines in wind farm arrays. To obtain the flow field and operating parameters (thrust and power coefficients) of a given ducted wind turbine (DWT) design, the Reynolds averaged Navier-Stokes equations with the k - ω SST turbulence model were solved. The turbine rotor was modeled as an actuator disc and an Eppler E423 airfoil was used for the duct cross-section. The design variables included the thrust coefficient and axial position of the rotor inside the duct, the chord length and angle of attack of the duct cross-section, and the normal gap between the rotor tip and the duct. The results show that for a fixed chord length of the duct cross-section, designs for optimal CP and CP,total are significantly different. The design for maximal CP,total was characterized by a smaller angle of attack of the duct cross-section, a smaller rotor gap (tip clearance), and a downstream placement of the rotor when compared to the design for optimal rotor power coefficient. The power output was insensitive to the axial position of the rotor as long as the rotor was not placed in a position causing flow separation. Therefore, a smaller and cheaper DWT can be designed if the turbine is placed further downstream of the duct, as opposed to placing the rotor at the throat of the duct as done in all other studies.An optimal duct length of 15% of rotor diameter was identified for CP,total where a total power coefficient of 0.7 was obtained. This is significantly greater than the Betz-Joukowski limit and demonstrates the capability of DWTs in achieving power outputs per device area greater than open-rotor wind turbines. The effect of duct length on the optimal design for CP,total was also identified. Similar to open-rotor wind turbines, the optimal thrust coefficient remained close to 0.9. The optimal normal rotor gap was close to the estimated boundary layer thickness of the duct cross-section. As the duct length increased, the optimal angle of attack decreased and the optimal position of the rotor moved further upstream in the duct. These variations of optimal design for CP,total with duct length were explained based on the role of the annular jet forming between the rotor and duct in inhibiting flow separation, which is often accompanied by a large drop in power output.A comparison of wakes of open and ducted wind turbines with similar total power coefficients was carried out. The results showed that the RANS actuator disc model predictions of the far wake flow field agree well with experimental results when the turbulence intensity at the rotor is close to that of experimental data. The wake recovery results, based on the total device diameter namely the rotor diameter for open wind turbines and the duct exit diameter for DWTs, showed that the rate of wake recovery of the DWT was significantly slower than the wake recovery rate of open-rotor wind turbines. This was attributed to the additional momentum deficit of the wake because of the drag force on the duct.

ISBN: 9798460408436Subjects--Topical Terms:

649730
Mechanical engineering.
Subjects--Index Terms:

Actuator disc

Optimal Aerodynamic Design of Ducted Wind Turbines.
LDR:04699nmm a2200385 4500 001 2343053
005 20220415160128.5
008 241004s2021 ||||||||||||||||| ||eng d
020 $a 9798460408436
035 $a (MiAaPQ)AAI28716760
035 $a AAI28716760
040 $a MiAaPQ $c MiAaPQ
100 1 $a Bagheri-Sadeghi, Nojan. $3 3681495
245 1 0 $a Optimal Aerodynamic Design of Ducted Wind Turbines.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2021
300 $a 78 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-04, Section: B.
500 $a Advisor: Helenbrook, Brian;Visser, Kenneth.
502 $a Thesis (Ph.D.)--Clarkson University, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a The presence of a duct around a wind turbine can significantly improve its power output by increasing the mass flow rate through the rotor. This thesis aims at determining the optimal aerodynamic design of ducted wind turbines for either maximal power per rotor area, CP, or maximal power per total frontal device area, CP,total. Additionally, a comparison of the pwake recovery rate of ducted and open-rotor wind turbines is carried out with the goal of determining the suitability of using ducted wind turbines in wind farm arrays. To obtain the flow field and operating parameters (thrust and power coefficients) of a given ducted wind turbine (DWT) design, the Reynolds averaged Navier-Stokes equations with the k - ω SST turbulence model were solved. The turbine rotor was modeled as an actuator disc and an Eppler E423 airfoil was used for the duct cross-section. The design variables included the thrust coefficient and axial position of the rotor inside the duct, the chord length and angle of attack of the duct cross-section, and the normal gap between the rotor tip and the duct. The results show that for a fixed chord length of the duct cross-section, designs for optimal CP and CP,total are significantly different. The design for maximal CP,total was characterized by a smaller angle of attack of the duct cross-section, a smaller rotor gap (tip clearance), and a downstream placement of the rotor when compared to the design for optimal rotor power coefficient. The power output was insensitive to the axial position of the rotor as long as the rotor was not placed in a position causing flow separation. Therefore, a smaller and cheaper DWT can be designed if the turbine is placed further downstream of the duct, as opposed to placing the rotor at the throat of the duct as done in all other studies.An optimal duct length of 15% of rotor diameter was identified for CP,total where a total power coefficient of 0.7 was obtained. This is significantly greater than the Betz-Joukowski limit and demonstrates the capability of DWTs in achieving power outputs per device area greater than open-rotor wind turbines. The effect of duct length on the optimal design for CP,total was also identified. Similar to open-rotor wind turbines, the optimal thrust coefficient remained close to 0.9. The optimal normal rotor gap was close to the estimated boundary layer thickness of the duct cross-section. As the duct length increased, the optimal angle of attack decreased and the optimal position of the rotor moved further upstream in the duct. These variations of optimal design for CP,total with duct length were explained based on the role of the annular jet forming between the rotor and duct in inhibiting flow separation, which is often accompanied by a large drop in power output.A comparison of wakes of open and ducted wind turbines with similar total power coefficients was carried out. The results showed that the RANS actuator disc model predictions of the far wake flow field agree well with experimental results when the turbulence intensity at the rotor is close to that of experimental data. The wake recovery results, based on the total device diameter namely the rotor diameter for open wind turbines and the duct exit diameter for DWTs, showed that the rate of wake recovery of the DWT was significantly slower than the wake recovery rate of open-rotor wind turbines. This was attributed to the additional momentum deficit of the wake because of the drag force on the duct.
590 $a School code: 0049.
650 4 $a Mechanical engineering. $3 649730
650 4 $a Energy. $3 876794
650 4 $a Alternative energy. $3 3436775
653 $a Actuator disc
653 $a Diffuser augmented wind turbine
653 $a Ducted wind turbine
653 $a Optimization
653 $a Shrouded wind turbine
653 $a Wake recovery
690 $a 0548
690 $a 0791
690 $a 0363
710 2 $a Clarkson University. $b Mechanical Engineering. $3 2093980
773 0 $t Dissertations Abstracts International $g 83-04B.
790 $a 0049
791 $a Ph.D.
792 $a 2021
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28716760