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Publications (46)
This paper investigated the integral length scales of turbulence in a low-roughness atmospheric surface layer (ASL), characterised by very smooth terrain in the Utah desert during near-neutral conditions, and evaluated the Engineering Sciences Data Unit (ESDU) 85020 and 86010 predictions for the turbulence length scales in a low-roughness ASL. The...
This paper investigated the influence of the turbulent wind fluctuations in the lowest 10 m of the atmospheric boundary layer (ABL), depending on the surface roughness of the terrain surrounding a heliostat field, on the required dimensions and material cost of the structural heliostat components to resist the combined bending and torsional stresse...
This paper investigates a stowing strategy of a heliostat field based on wind speed and direction, in terms of the potential benefit of additional energy collection through the partial stowing of heliostats within an azimuth angle range with reduced operating wind loads. Correlations of one-minute wind speed and DNI at a heliostat field site with t...
Accurate estimation of the static and dynamic wind loads on heliostats based on detailed measurement and characterisation of turbulence is crucial to avoid structural failure and reduce the cost of the structural heliostat components. Wind load predictions for heliostats are not specified in design standards for buildings because of a heliostat’s n...
Non-uniform pressure distributions on the heliostat surface due to turbulence in the atmospheric boundary layer (ABL) have a significant impact on the maximum bending moments about the hinge of and pedestal base of a conventional pedestal-mounted heliostat. This paper correlates the movement of the centre of pressure due to the mean and peak pressu...
The design of heliostats throughout a concentrated solar power (CSP) plant are currently of uniform design, however, research into the variation in heliostat wind loading within a radially staggered field array can provide insight into potential material cost savings in heliostat field design. Experimental investigation was carried out on a field a...
Wind loads are a major driver of heliostat cost. Standardized methods and tools are needed for a more detailed understanding of the static and dynamic loads of a heliostat design. This will enable cost reduction of wind-dependent heliostats to avoid unnecessarily conservative heliostat designs and increase field efficiency and reliability to reduce...
This study investigated high-frequency load fluctuations on a rectangular heliostat model in a boundary layer wind tunnel experiment. Statistical methods for peak wind load predictions were compared with load distributions through load cell and surface pressure measurements on the heliostat model placed in two simulated atmospheric boundary layers...
The Heliostat Consortium (HelioCon) Wind Load Subtask was initiated with the aim of bringing research work pertaining to wind load measurement, characterization, and prediction taking place across several tasks, including Advanced Manufacturing, Components and Controls, and Field Deployment. The cross-cutting wind load subtopic in the HelioCon road...
Heliostat-based concentrating solar-thermal power (CSP) systems can offer immense potential to provide low-cost, dispatchable renewable thermal and electrical energy to help achieve 100% decarbonized energy infrastructure in the United States. Heliostats are a major determinant of both capital cost and performance of state-of-the-art commercial mol...
This study investigated the sensitivity of turbulence length scales to atmospheric stability in the eddy surface layer. Field measurements of three-dimensional wind velocity with arrays of ultrasonic anemometers at the University of Adelaide Atmospheric Boundary Layer Research Facility (ABLRF) were used to estimate turbulence statistics including s...
Whilst multi-hole pressure probes are commonly used for measuring complex three-dimensional flows, they are expensive and can be easily damaged. As a result, a robust four-hole pressure probe has been developed as an inexpensive alternative to currently-available multi-hole probes with the aim of making these instruments more accessible to aerodyna...
This study examines the effectiveness of mesh grids in heliostat field perimeter fences and edge-mounted devices for heliostat wind load reduction. Two experimental studies were conducted: (1) the effect of mesh porosity and non-dimensional longitudinal distance of a perimeter fence upstream on the forces on a heliostat, and (2) the effect of mesh...
Manipulation of turbulence within an atmospheric boundary layer flow by application of woven wire mesh fences is investigated. Turbulence properties behind fences of different porosities and mesh opening widths were determined from velocity measurements in a wind tunnel. It is found that with the application of a fence with a porosity of 0.46, the...
The aerodynamic loads on heliostats have been investigated through an extensive range of experimental studies at the University of Adelaide in association with the Australian Solar Thermal Research Institute (ASTRI). Applied modelling techniques using spires and roughness elements were adopted for generation and characterisation of the temporal and...
The mean and spectral characteristics of turbulence in the wake flow of a flat plate model resembling a heliostat in the atmospheric boundary layer flow are investigated in a wind tunnel experiment. Mean velocity and turbulence kinetic energy were characterized in the wake of a heliostat model at three elevation angles up to a distance of eight tim...
The aerodynamic loads on heliostats have been investigated through an extensive range of experimental studies at the University of Adelaide in association with the Australian Solar Thermal Research Institute (ASTRI). Applied modelling techniques using spires and roughness elements were adopted for generation and characterisation of the temporal and...
The unsteady surface pressure distribution on heliostats in a tandem arrangement is investigated in this experimental study. The differential pressure on the panel of a heliostat model is measured for a range of gaps, between the two tandem heliostats, varying from 1 to 7 times the chord length dimension of the panel. The heliostat models are place...
This paper investigated the dynamic fluctuations of the high-frequency surface pressure and force measurements on an instrumented scale-model heliostat within a turbulent ABL generated in a wind tunnel. Peak aerodynamic load coefficients on the model heliostat calculated following the equivalent static wind load method were consistent with previous...
Mismatch of turbulence spectra from the corresponding full-scale conditions is a common challenge in wind tunnel modelling of unsteady wind loads on small-scale structures, such as solar panels, heliostats and low-rise buildings. Understanding the effect of this mismatch on the unsteady wind loads is necessary for providing an accurate estimation o...
The correlation between turbulence intensity and length scale and the lift force on a horizontal flat plate in an atmospheric boundary layer flow is investigated in this study. Experiments were conducted in a large-scale wind tunnel to measure the peak loads on flat plate models of various chord length dimensions at different heights within simulat...
During the operation of a concentrating solar thermal (CST) power tower plant, heliostat mirrors inclined at different angles act as bluff bodies that are exposed to large drag loads from the wind. This experimental study investigates the aerodynamic loads on a heliostat in a tandem configuration, to determine the significance of the shielding effe...
The effect of intensity and length scale of turbulence on the mean and fluctuating drag forces on a flat plate normal to a boundary layer flow is investigated. Experiments were conducted at the University of Adelaide large wind tunnel to measure the drag force on flat plates of different areas. Two boundary layers of different depths were generated...
Dynamic wind effects on small physical structures have been shown to be dependent on the spatial distribution and three-dimensional structure of highly sheared and elongated eddies embedded in anisotropic turbulence due to the presence of the ground. The turbulence length scales in the lowest 10 m of a low-roughness atmospheric surface layer (ASL)...
This experimental study outlines a method to calculate the design wind loads on heliostats, based on peak wind load coefficients reported in the heliostat literature and aerodynamic shape factors derived from high-frequency pressure measurements on an isolated heliostat at different elevation and azimuth angles in a boundary layer wind tunnel. The...
This experimental study outlines a method to calculate the design wind loads on heliostats, based on peak wind load coefficients reported in the heliostat literature and aerodynamic shape factors derived from high-frequency pressure measurements on an isolated heliostat at different elevation and azimuth angles in a boundary layer wind tunnel. The...
This paper investigates the effects of turbulence in the atmospheric boundary layer (ABL) on the peak wind loads on heliostats in stow position in isolation and in tandem configurations with respect to the critical scaling parameters of the heliostats. The heliostats were exposed to a part-depth ABL in a wind tunnel using two configurations of spir...
Concentrating solar thermal (CST) power tower (PT) is an emerging renewable technology for large-scale electricity production, however the main limitation is their significantly larger levelised cost of electricity (LCOE) relative to base load energy systems. One opportunity to lower the LCOE is to reduce the capital cost of heliostats through opti...
Turbulence characteristics in the atmospheric boundary layer and their effect on the peak wind loads on heliostats measured in a wind tunnel
Concentrating solar thermal (CST) power tower (PT) is one of the most promising renewable technologies for large-scale electricity production, however the main limitation of PT systems is their significantly larger levelised cost of electricity (LCOE) relative to base load energy systems. One opportunity to lower the LCOE is to reduce the capital c...
![FIGURE 2. Comparison of field experiment data [5] with the logarithmic...](profile/Matthew-Emes/publication/317983613/figure/fig2/AS:510379453566976@1498695352153/Comparison-of-field-experiment-data-5-with-the-logarithmic-mean-velocity-and-turbulence_Q320.jpg)
Dynamic amplification and gust effects from turbulence can increase wind loads significantly over and above the static wind loads that have been used for heliostat design. This paper presents the results of analyzing the relationship between gust factor and turbulence intensity within the atmospheric boundary layer (ABL) based on the high fidelity...
The velocity fluctuations within the atmospheric boundary layer (ABL) and the wind direction are two important parameters which affect the resulting loads on the heliostats. In this study, the drag force on a square heliostat within the ABL at different turbulence intensities is simulated. To this end, numerical analysis of the wind loads have been...
The Australian Solar Thermal Research Initiative (ASTRI) aims to develop a high optical quality heliostat with target cost – manufactured, installed and operational – of 90 AUD/m2. Three different heliostat design concepts are described, each with features identified during a prior scoping study as having the potential to contribute to cost reducti...
This paper assesses the influence on the levelised cost of electricity (LCOE) of the design wind speed at which heliostats in concentrating solar thermal (CST) power tower (PT) plants are stowed. Lowering the design wind speed for parking heliostats in the stow position reduces the cost of the heliostat field at the expense of a reduction in the en...
Questions
Question (1)
There is a lack of design standards for wind load predictions on heliostats. The effect of atmospheric boundary layer turbulence is one key consideration in the structural design of heliostats in concentrating solar thermal plants. As a first step to develop an engineering guideline in SolarPACES Task III, the Australian Solar Thermal Research Institute (ASTRI) heliostat project has developed a spreadsheet to estimate the heliostat wind loads, using the aerodynamic wind load coefficients on a scale-model square heliostat in the University of Adelaide wind tunnel. The spreadsheet can be downloaded from the "Research data" tab on the following link on the Centre for Energy Technology (CET) website at the University of Adelaide. The design wind speeds of heliostats for operating and stow positions is one important specification, but also the turbulence generated by a given terrain with defined surface roughness should be considered. What other important factors should be assessed?
