Jonathan Whale

An experimental and numerical study of the vortex structure in the wake of a wind turbine

An experimental investigation into the properties of the vortex wake behind a wind turbine rotor has been carried out at model scale, using Particle Image Velocimetry (PIV). The two-blade model was operated at tip speed ratios in the range λ=3–8, and chord Reynolds numbers Re=6400–16 000. The blades were untwisted, with flat-plate aerofoil profile. Measurements of wake velocity and vorticity were obtained for a two-dimensional flow field representing an axial cross-section of the wake, extending 2.9 rotor diameters downstream of the rotor. The vorticity maps were compared with calculations made using the Rotor Vortex Lattice Method (ROVLM), an inviscid free-wake code recently developed at the University of Stuttgart. The PIV and ROVLM data show qualitative agreement in terms of the shape of the wake boundary, including downstream wake contraction, and quantitative agreement in terms of the tip vortex pitch. It appears that the fundamental behaviour of the helical vortex wake may be relatively insensitive to blade chord Reynolds number, so long as similarity of tip speed ratio is observed.

A study of the near wake structure of a wind turbine comparing measurements from laboratory and full-scale experiments

Wake flow measurements have been performed using the technique of particle image velocimetry (PIV) at stations downstream from a model wind turbine rotor, and evaluated against experimental data from two full-scale machines. Comparisons include both mean velocity and turbulent intensity cross-wake profiles at a range of tip speed ratios. The application of PIV to the study of wind turbine wakes is described in detail, including the steps required to ensure appropriate and accurate simulation of the flow field conditions. The results suggest that the PIV method is a potentially useful tool in the investigation of detailed wake flow, though significant differences are observed between wake velocity deficits at full- and model scale. These are discussed with regard to scale effect, the influence of terrain, model similarity, and the phenomenon of wake meandering and effective cross-wake smoothing.

Correcting inflow measurements from HAWTs using a lifting-surface code

Aerodynamic performance data from a rotating HAWT blade is typically correlated with measurements of a local inflow angle, obtained by flow angle sensors attached to the leading edge of the blade section. In order to provide accurate performance data for 2D bladeelement/momentum codes, the 3D field data must be corrected in terms of the section angle of attack. A 3D Lifting-Surface Inflow Correction Method (LSIM) has been developed with the aid of a vortex-panel code in order to calculate the relationship between the local flow angle and the angle of attack. Sets of intlow correction curves were produced for each spanwise station of interest. The method has been tested using hypothetical 3D input data, based on measurements from the Combined Experiment Rotor at the National Renewable Energy Laboratories and wind tunnel tests at Deli% University of Technology. The method was shown to successfully produce a converged solution for the inflow correction curves. The results show the importance of using the 3D LSIM correction instead of a 2D correction, particularly at the inboard sections of the blade where the upwash at the sensor is affected by post stall effects and changes in spanwise circulation distribution on the blade. Copyright

A model of the injection moulding process

This paper is concerned with the injection moulding process, in which hot molten plastic is injected under high pressure into a thin cold mould. Assuming that the velocity and temperature profiles across the mould maintain their shape, a simple steady state model to describe the behaviour of a Newtonian fluid during the rilling stage is developed. Various phenomena of the process are examined, including the formation of a layer of solid plastic along the walls of the mould, and the relationship between the flux of liquid plastic through the mould and the average pressure gradient along the mould. In any given situation, it is shown that there is a range of pressures and injection temperatures which will give satisfactory results.

Correcting Inflow Measurements From Wind Turbines Using a Lifting-Surface Code

In order to provide accurate blade element data for wind turbine design codes, measured three-dimensional (3D) field data must be corrected in terms of the (sectional) angle of attack. A 3D Lifting-Surface Inflow Correction Method (LSIM) has been developed with the aid of a vortex-panel code in order to calculate the relationship between measured local flow angle and angle of attack. The results show the advantages of using the 3D LSIM correction over 2D correction methods, particularly at the inboard sections of the blade where the local flow is affected by post-stall effects and the influence of the blade root.

Enhanced EV and ICE vehicle energy efficiency through drive cycle synchronisation of deferred auxiliary loads

This research investigates energy efficiency improvements by synchronising auxiliary air–conditioning (AC) with the vehicle drive train on a real road driving cycle pattern. The research findings are applicable to electric vehicles (EVs), internal combustion engine (ICE) vehicles, and hybrids. An EV–converted Ford Focus was configured to operate the AC compressor solely from kinetic energy recovered from the drive train when coasting or slowing down. Test drives with the Ford Focus with standard AC operation increased the energy consumption by 11.6% compared to AC off, yet when the vehicle was synchronised with the drive train the energy consumption increased by only 5.8% compared to AC off, an energy saving of 8.1 Wh km−1. The configuration maintained comfortable cabin conditions (temperature and humidity) similar to driving with a standard AC system configuration. In vehicles with an interconnected automatic AC and engine management system data–bus, this efficiency improvement may require a software update only.

Application of particle image velocimetry to wind turbine wakes

Wind turbine performance is critically dependent on the geometry of the rotor wake. Acquisition of detailed wake data is of major importance for further development of wind turbine studies. This paper presents the results of a preliminary experimental study of the flow past a model turbine using Particle Image Velocimetry (PIV), a whole field velocimetry method, with a scanning beam system of flow illumination. The results strongly validate the PIV technique applied to studying wind turbine wakes. PIV provides the means whereby detailed full-field data can be obtained and an experimental data base for wake velocities and structure established.

Performance evaluation of regenerative braking systems

This research evaluates the energy gain from a regenerative braking system (RBS) in a commercial electric vehicle (EV), the OEM Mitsubishi i-MiEV. Measurements were conducted in a controlled environment on a commercial chassis dynamometer using international drive cycle standards. The energy recovery of the vehicle was modelled and the output of the model was compared with results from the chassis dynamometer driving. The experiments were original as they coupled changes in energy recovered and driving range due to the RBS settings with investigations into the time of use of the friction brake. Performance tests used two different drive cycle speed profiles and various RBS settings to compare energy recovery performance for a broad range of driving styles. The results show that due to reduced energy consumption, the RBS increased the driving range by 11–22% depending on RBS settings and the drive cycle settings on the dynamometer. The results further showed that driving an EV with a RBS uses the friction brakes more efficiently, which will reduce brake pad wear. This has the potential to improve air quality due to reduced brake pad dust and reduces the maintenance costs of the vehicle. The findings were significant since they showed that friction time of use, a parameter neglected in RBS testing, plays an important part in the efficient operation of an EV. The overall results from the vehicle energy recovery modelling showed good agreement with the data from drive cycle testing and the model has potential to be further developed to gain greater insight into vehicle RBS braking behaviour for EVs in general.

Context and Community Renewable Energy Development in Western Australia: Towards Effective Policy and Practice

Community renewable energy projects are contributing diverse sustainability benefits in a transforming energy landscape, but in Western Australia, projects are few and far between, and the state is being left behind in national policy discussions. Drawing upon a socio-technical framework which conceptualises the context of innovation journeys according to patterns in the context, we investigate Western Australia and its major electricity network as a site for community-driven renewable energy development. Our case study analysis suggests that project development in Western Australia to date has survived in niche pockets, which have been unusually conducive to community energy development, in a context otherwise riddled with political, technical and regulatory hurdles.

A comparative analysis of built environment and open terrain wind data by higher order statistics and performance evaluation of 5 kW HAWT using FAST

Small wind turbines (SWT) that are designed as per the IEC 61400-2 standard suffer structural and operational complexities when operating in the built environment, because such environments impose stochastic variations in wind speed and turbulence. The wind conditions in flat terrain of Ostergarnsholm (OG) Island, Sweden and built environment of Port Kennedy (PK), Australia are compared for turbulence intensity (TI) and intermittency. The TI of the PK wind field was 24% at mean wind speed of 15 m/s, which was higher than the Normal Turbulence Model (NTM) indicated in IEC 61400-2. The TI in the open terrain was below 18% for all mean wind speeds. Similarly, for three chosen wind speed bins within a SWTs operating range, the urban wind field had higher intermittency for smaller timescales but resulted in smaller intermittency as the time lag increased. The effect of these measured wind fields on the performance and loading of a turbine was studied at the three chosen wind speed bins using an aeroelastic model of a 5 kW SWT that was developed in FAST. The predicted output statistics using measured wind fields were compared with the assumed wind fields in the IEC 61400-2 standard. The rotor thrust and blade flapwise bending moment with PK wind data were higher than that of the IEC standard due to the increased turbulence in the inflowing wind indicating the inadequacy in the current wind standard applied for such SWTs for urban installations.