On the potential of the ideal diffuser augmented wind turbine: an investigation by means of a momentum theory approach and of a free-wake ring-vortex actuator disk model

被引:38
作者
Bontempo, R. [1 ]
Manna, M. [1 ]
机构
[1] Univ Napoli Federico II, Dipartimento Ingn Ind, Via Claudio 21, I-80125 Naples, Italy
关键词
Diffuser augmented wind turbine; Ducted wind turbine; Tidal turbine; Hydrokinetic turbine; Actuator disk; PERFORMANCE ANALYSIS; ROTOR; FLOW; OPTIMIZATION;
D O I
10.1016/j.enconman.2020.112794
中图分类号
O414.1 [热力学];
学科分类号
摘要
Diffuser-augmented wind-turbines are drawing increasing attention since they can beat the Betz-limit referred to the rotor-area. However, their diffusion is still prevented by some issues including: 1) the attainable power has not yet been shown to be larger than that of an open-turbine with the same frontal-area, 2) the classical analysis methods rely on the one-dimensional-flow and no-tip-gap assumptions whose impact has never been quantified. The paper addresses these two items investigating the potential of ideal diffuser-augmented wind-turbines using a newly-developed Axial-Momentum-Theory approach, and an extended version of a free-wake ring-vortex actuator-disk model. In comparison with similar methods, the novelty of the first approach is that it accounts for the two-dimensional effects and the tip-gap presence. Since this approach cannot evaluate the performance of a turbine for a given duct-geometry, a ring-vortex method is also developed. This is the first low-computational-cost method relying on the exact solution of the inviscid-flow through a uniformly-loaded ducted-turbine with a finite-size tip-gap. It strongly couples the flow induced by the duct and the wake which are modelled as the superposition of ring-vortices. The combined use of axial-momentum and ring-vortex methods leads to the following results. Firstly, it is clearly shown that an ideal diffuser-augmented turbine can extract more power than a Betz disk with the same frontal-area. To strengthen this statement, a new duct geometry with a remarkable value of the exit-area power-coefficient equal to 0.6098 is presented. This value is significantly higher than that of a base-line NACA5415 duct profile, i.e. 0.4800. Secondly, the impact of the one-dimensional-flow and no-tip-gap assumptions is evaluated. It is also shown that the tip-gap has negligible effects. Moreover, the one-dimensional-flow hypothesis has a low impact for high values of the rotor load, while the errors grow up decreasing the rotor thrust.
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页数:17
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共 61 条
  • [1] Experimental and numerical investigations of flow fields behind a small wind turbine with a flanged diffuser
    Abe, K
    Nishida, M
    Sakurai, A
    Ohya, Y
    Kihara, H
    Wada, E
    Sato, K
    [J]. JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS, 2005, 93 (12) : 951 - 970
  • [2] Avallone F, 2019, P AIAA SCIT 2019 FOR, P1294
  • [3] Ducted wind turbine optimization and sensitivity to rotor position
    Bagheri-Sadeghi, Nojan
    Helenbrook, Brian T.
    Visser, Kenneth D.
    [J]. WIND ENERGY SCIENCE, 2018, 3 (01) : 221 - 229
  • [4] Batchelor GK., 1967, INTODUCTION FLUID DY
  • [5] Energy conversions in the venturi jet pump.
    Betz, A
    [J]. NATURWISSENSCHAFTEN, 1929, 17 : 160 - 164
  • [6] A ring-vortex actuator disk method for wind turbines including hub effects
    Bontempo, R.
    Manna, M.
    [J]. ENERGY CONVERSION AND MANAGEMENT, 2019, 195 : 672 - 681
  • [7] Highly accurate error estimate of the momentum theory as applied to wind turbines
    Bontempo, R.
    Manna, M.
    [J]. WIND ENERGY, 2017, 20 (08) : 1405 - 1419
  • [8] The axial momentum theory as applied to wind turbines: some exact solutions of the flow through a rotor with radially variable load
    Bontempo, R.
    Manna, M.
    [J]. ENERGY CONVERSION AND MANAGEMENT, 2017, 143 : 33 - 48
  • [9] Actuator disc methods for open propellers: assessments of numerical methods
    Bontempo, R.
    Manna, M.
    [J]. ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUID MECHANICS, 2017, 11 (01) : 42 - 53
  • [10] Effects of the duct thrust on the performance of ducted wind turbines
    Bontempo, R.
    Manna, M.
    [J]. ENERGY, 2016, 99 : 274 - 287