- Title
- Aspects of the blade tower interaction of 2-blade 5kW horizontal wind turbine operating in highly turbulent conditions
- Creator
- Chu, Mu
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2019
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- The research work documented in this thesis is focused on understanding how flow shadow from a downstream monopole wind turbine tower effects the blades on a high-efficiency small wind turbine operating in highly turbulent wind flows. Experimental measurement campaigns and computational fluid dynamics simulations were undertaken to investigate this phenomenon. All experimental campaigns reported in this thesis were done using a two-bladed upwind 5kW Aerogenesis wind turbine over a range of turbine operating conditions. Computational fluid dynamics modelling of the flow over the turbine and tower and modelling the fluid blade-structure interactions were done using the ANSYS suite of software. One of the turbine’s 2.5 m long composite blades was instrumented with 12 strain gauges attached to the blade’s pressure and suction surfaces to measure its mechanical response during operation. Signals from these gauges were initially acquired using a V-link data acquisition system, but due to incompatibility with other data acquisition systems used on the turbine, this system was replaced with an Arduino-based data acquisition system. The Arduino data acquisition system, built by the Wind Energy Group at The University of Newcastle, was modular allowing easy integration with other data acquisition systems; important aspects of this data acquisition system are documented in this thesis. The blade’s composite structure was modelled using ANSYS Composite PrepPost with a series of static and dynamic blade tests undertaken to verify the accuracy of this finite element model, and to later verify a formulation that infers blade deflections from strain gauges signals. The derivation of this formulation is documented in this thesis. The ANSYS structural model of the blade was also used to remove the centrifugal strain component from the strain gauge signals, allowing the blade’s operating flapwise deflections to be inferred. On-site experiments were carried out to determine the blade’s flapwise deflection for a range of wind conditions and for two different tower diameters and associated blade tower clearances. Signals from the strain gauges attached to the blade were acquired at 500 Hz allowing detailed examination of the structural response of the blade as it passed in front of the tower. Analysis of these experimental results indicate that blade tower shadow caused a slight reduction in blade deflection when the blade past in front of the tower. Fast Fourier Transform (FFT) was performed on the blade strain gauge data for measurement undertaken with both tower diameters, with the 1P (once per revolution) and 2P (twice per revolution) signals clear visible and distinguishable. The 1P frequency coincided with the blade rotating frequency. A number of 2D and 3D simulations were undertaken confirming that the Shear Stress Transport turbulence model combine with a hybrid mesh strategy was the most appropriate combination to simulate flow over a full-sized model of the 5 kW Aerogenesis wind turbine. The blade’s aeroelastic response was modelled by linking ANSYS CFX and ANSYS Mechanical to perform the fluid blade-structure interaction simulations. These simulations indicated that wind shear across the blade rotor resulted in minimal variation in the blade’s flapwise deflection. For turbine yaw rates of less than ±12°/sec, gyroscopic loading had a negligible contribution to the strain measured on an operating blade. Simulations indicated that increasing the tower diameter and subsequently reducing the blade tower gap, reduced blade deflection by only 3 mm. This small change in blade deflection as it passed in front of the turbine tower is likely to have minimal effect on the blade’s fatigue life.
- Subject
- small wind turbine; ANSYS simulation; highly turbulent conditions; blade-tower interaction
- Identifier
- http://hdl.handle.net/1959.13/1407988
- Identifier
- uon:35800
- Rights
- Copyright 2019 Mu Chu
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 5 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 725 KB | Adobe Acrobat PDF | View Details Download |