Improvement of startup performance of the drag-type hydrokinetic rotor through two-stage configuration

Kang, Can; Zhao, Hexiang; Li, Bing; Gong, Wei; Zhu, Yang

doi:10.1016/j.oceaneng.2021.109677

Cited by 6 publications

(4 citation statements)

References 38 publications

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“…It has been reported that for certain azimuthal angles, the conventional drag-based VAWT could not start, but the spiral blade VAWT did, at all azimuthal angles. Like Zhao et al [26] and Kang et al [27], rapid initial acceleration and then transition to steady operation of the VAWT have been reported, with peak ω increasing as wind speed increases. It has also been recorded that the spiral blade VAWT generated significantly higher torque.…”

Section: Start-up Dynamics Of Drag-based Turbinesmentioning

confidence: 62%

“…At the end of the transition stage, the angular velocity fluctuates periodically over a small range representing a stable operation of the rotor. Kang et al [27] have carried out further investigations with the aim to improve the start-up of the hydrokinetic turbine considered by Zhao et al [26]. They developed a two-stage hydrokinetic turbine (top and bottom configuration) and noticed a similar pattern of start-up to single stage turbine.…”

Section: Start-up Dynamics Of Drag-based Turbinesmentioning

confidence: 99%

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Effect of Stator Blades on the Startup Dynamics of a Vertical Axis Wind Turbine

et al. 2022

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Vertical Axis Wind Turbines (VAWTs) are omni-directional, low-cost, low-efficiency wind power extractors. A conventional drag-based VAWT consists of multiple thin rotor blades with a typical peak Tip Speed Ratio (λ) of < 1. Their lower cut-in speed and maintenance cost make them ideal for power generation in urban environments. Numerous studies have been carried out analysing steady operation of VAWTs and quantifying their performance characteristics, however, minimal attention has been paid to their start-up dynamics. There are a few recent studies in which start-up dynamics of lift-based VAWTs have been analysed but such studies for drag-based VAWTs are severely limited. In this study, start-up dynamics of a conventional multi-blade drag-based VAWT have been numerically investigated using a time-dependant Computational Fluid Dynamics (CFD) solver. In order to enhance the start-up characteristics of the drag-based VAWT, a stator has been integrated in the design assembly. The numerical results obtained in this study indicate that an appropriately designed stator can significantly enhance the start-up of a VAWT by directing the flow towards the rotor blades, leading to higher rotational velocity (ω) and λ. With the addition of a stator, the flow fields downstream the VAWT becomes more uniform.

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Section: Start-up Dynamics Of Drag-based Turbinesmentioning

confidence: 62%

Section: Start-up Dynamics Of Drag-based Turbinesmentioning

confidence: 99%

Effect of Stator Blades on the Startup Dynamics of a Vertical Axis Wind Turbine

et al. 2022

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“…Kang [30] investigated the start-up dynamics of a single and two-stage drag-type hydrokinetic rotor numerically. The two-stage rotor, shown in Figure 3(b), is formed by splitting a conventional singlestage rotor in half using an end plate and rotating the blades in one of the stages by 90°.…”

Section: Drag-based Rotorsmentioning

confidence: 99%

“…Figure 3. Different lift-based rotor designs (a) Conventional rotor[29], Two-stage rotor[30], (c) Spiral rotor[27] …”

mentioning

confidence: 99%

Start-up Dynamics of Vertical Axis Wind Turbines: A Review

Lough,

Asim,

Coull

et al. 2023

J. Phys.: Conf. Ser.

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Vertical Axis Wind Turbines (VAWTs) are becoming increasingly popular for wind power extraction due to their simpler design, lower manufacturing and maintenance costs. The omni-directionality of these power generating machines make them more suitable for operation both under lower wind speeds and highly transient winds. The key wind power extraction component of VAWTs is their rotor, which is conventionally either Drag-based or Lift-based, with the latter being more widely studied in the published literature due to its higher power coefficient compared to its counterpart. The lift-based rotor comprises of aerodynamically profiled blades, while the drag-based rotor comprises of thin cup-shaped blades. The start-up of both these types of VAWT rotors has been an area of active research in the last decade. These studies have been conducted using numerical and experimental methods focusing on key parameters related to the start-up dynamics of VAWTs. Many of these research studies complement each other’s findings, however, there are also a number of aspects where there are disagreements and/or significant knowledge gaps that need to be highlighted in order to accelerate scientific efforts strategically. In the present study, we aim to address these challenges through a thorough and critical review of the published literature on VAWTs’ start-up dynamics, leading towards the identification of key knowledge gaps.

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