Horia Hangan - Academia.edu (original) (raw)
Papers by Horia Hangan
Journal of Web Engineering, Jul 14, 2006
Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental ... more Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental results for one swirl ratio: S = 0.28. The simulations are then extended for higher swirl ratio and the variability of the macro-flow dynamics is observed. For lower swirl a laminar surface vortex forms which then breaks-up aloft into a turbulent vortex which with increasing swirl descends towards the surface.
Performance levels and acceptance criteria for wind hazards 29 Performance levels and acceptance ... more Performance levels and acceptance criteria for wind hazards 29 Performance levels and acceptance criteria for buildings subject to coastal inundation Measurement of windstorm resilience and benefits of performance-based design 30 Sound engineering basis for flood resistant design that is not based on flood insurance requirements Analysis procedures for nonlinear system behavior used in performance-based design Cyber-based tools to support performance-based design Legend: Highest priority R&D topic; High priority R&D topic; Medium priority R&D topic GCR 14-973-13 1: Introduction 1-1 Chapter 1 1 As defined by NIST, the term measurement science includes "the development of performance metrics, measurement methods, predictive tools, and protocols as well as reference materials, data, and artifacts; the conduct of inter-comparison studies and calibrations; the evaluation and/or assessment of technologies, systems, and practices; and, the development and/or dissemination of technical guidelines and basis for standards, codes, and practices-in many instances via test beds, consortia, and/or other partnerships with the private sector." 2 Fatality and property loss figures developed from data published by the National Oceanic and Atmospheric Administration (NOAA, 2013a) GCR 14-973-13 4: Recommended Research and Development Topics 4-1 Chapter 4 Recommended Research and Development Topics 4.1
A characterization of mean and turbulent flow behaviour over complex topography was conducted usi... more A characterization of mean and turbulent flow behaviour over complex topography was conducted using a largescale (1:25) model of Bolund Hill in the WindEEE Dome at Western University. The specific topographic feature considered was an escarpment. A total of eight unique inflow conditions were tested in order to isolate the impact of key parameters such as Reynolds number, inflow shear profile and upstream effective roughness, on flow behaviour over the escarpment. The results show that the mean flow behaviour was generally not affected by the Reynolds number, however a slight increase in speed-up over the escarpment was observed for cases with lower upstream roughness. The shape of the inflow wind shear profile also had a minor impact on the mean flow near the escarpment. More significant effects were observed in the turbulent flow behaviour, where the turbulent kinetic energy (TKE) over the escarpment was found be a strong function of upstream roughness and a weak function of the Reynolds number. The local change in the upstream wind shear was found to have the most significant influence on the TKE magnitude, which more closely approximated the full-scale TKE data, and had not been previously observed in wind tunnel modelling of this topography. 1 Introduction Wind turbines over the last few decades have emerged as a reliable and cost-competitive means of producing clean, renewable electricity. Although typically built on relatively flat terrain such as plains and farmland, wind farms are increasingly being placed in more rugged, or complex, terrain, marked by abrupt changes in elevation (Palma et al., 2008). These sites often have strong wind resources, yet designing wind farms for these regions involves additional challenges due to the changes imposed by the terrain on the three-dimensional structure of the wind, such as speed-up regions, changes to the wind shear profile, large vertical wind velocities, and modification of turbulence characteristics (Walmsley and Taylor, 1996; Botta et al., 1998). As a result, the essential prediction of on-site wind conditions, often estimated from measurements at a limited number of mast locations, also becomes more challenging. The use of linearized models, the current industry standard for wind resource assessment and turbine micro-siting, proven to be very effective in gently sloping
In this study, the possibility of simulating some transient and deterministic extreme operational... more In this study, the possibility of simulating some transient and deterministic extreme operational conditions for horizontal axis wind turbines based on the IEC 61400-1 standard in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University was investigated. There are 60 fans (a matrix of 4 by 15 with 0.8m diameter each) on one of the walls of this hexagonal wind tunnel for creating straight flows which the power set-points for each fan can be specified individually. In addition, these fans have adjustable Inlet Guiding Vanes (IGV) that can be controlled uniformly across all of the fans. Using these capabilities, experiments were carried out for the Extreme Operational Gust (EOG), positive and negative Extreme Vertical Shear (EVS), and Extreme Horizontal Shear (EHS) cases, tailored for a 2.2 m HAWT scaled turbine. This study started by developing a numerical model for the test chamber, then using it to tune the fan setups for each extreme condition with proper scaling. Physical experiments then carried out using those settings, then a comparison made between the flow field time history and the prescribed conditions from the standard. The comparisons show promising results, this can be a contribution to future scholars investigating the interaction of the HAWT with these conditions in physical experiments.
Wind Energy Science, 2021
The power generation and loading dynamic responses of a 2.2 m diameter horizontal axis wind turbi... more The power generation and loading dynamic responses of a 2.2 m diameter horizontal axis wind turbine (HAWT) under some of the IEC 61400-1 transient extreme operational conditions, more specifically extreme wind shears (EWSs) and extreme operational gust (EOG), that were reproduced at the WindEEE Dome at Western University were investigated. The global forces were measured by a multi-axis force balance at the HAWT tower base. The unsteady horizontal shear induced a significant yaw moment on the rotor with a dynamic similar to that of the extreme event without affecting the power generation. The EOG severely affected all the performance parameters of the turbine.
Wind Energy Science, 2020
In this study, the possibility of simulating some transient and deterministic extreme operational... more In this study, the possibility of simulating some transient and deterministic extreme operational conditions for horizontal axis wind turbines based on the IEC 61400-1 standard using 60 individually controlled fans in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University was investigated. Experiments were carried out for the extreme operational gust (EOG), positive and negative extreme vertical shear (EVS), and extreme horizontal shear (EHS) cases, tailored for a scaled 2.2 m horizontal axis wind turbine. For this purpose, firstly a numerical model for the test chamber was developed and used to obtain the fans' configurations for simulating each extreme condition with appropriate scaling prior to the physical experiments. The results show the capability of using numerical modelling to predict the fans' setup based on which physical simulations can generate IEC extreme conditions in the range of interest.
Wind Energy Science Discussions, 2016
A characterization of mean and turbulent flow behaviour over complex topography was conducted usi... more A characterization of mean and turbulent flow behaviour over complex topography was conducted using a large-scale (1:25) model of Bolund Hill in the WindEEE Dome at Western University. The specific topographic feature considered was an escarpment. A total of eight unique inflow conditions were tested in order to isolate the impact of key parameters such as Reynolds number, inflow shear profile and upstream effective roughness, on flow behaviour over the escarpment. <br><br> The results show that the mean flow behaviour was generally not affected by the Reynolds number, however a slight increase in speed-up over the escarpment was observed for cases with lower upstream roughness. The shape of the inflow wind shear profile also had a minor impact on the mean flow near the escarpment. More significant effects were observed in the turbulent flow behaviour, where the turbulent kinetic energy (TKE) over the escarpment was found be a strong function of upstream roughness and a ...
Jwe 日本風工学研究会誌, Jul 14, 2006
Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental ... more Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental results for one swirl ratio: S = 0.28. The simulations are then extended for higher swirl ratio and the variability of the macro-flow dynamics is observed. For lower swirl a laminar surface vortex forms which then breaks-up aloft into a turbulent vortex which with increasing swirl descends towards the surface.
Particle Image Velocimetry (PIV) technique was employed to characterize the flow field of simulat... more Particle Image Velocimetry (PIV) technique was employed to characterize the flow field of simulated tornado vortices and to establish a relationship between laboratory generated tornadoes and the field ones. Field data collected by mobile Doppler radars were analyzed using a mathematical method namely the Ground-based Velocity Track Display (GBVTD) and the velocity fields were extracted. The horizontal velocity field of tornado vortices, simulated in Model WindEEE Dome, was measured using PIV for a wide range of vortex intensity. The substantial mismatch between the averaging time of the full-scale data and the laboratory data which is originated in the very small length scale of the simulation and the low sampling rate of the PIV system, was addressed and corrected using the Durst curve. Once modified, the velocity field of the simulated vortex was compared with that of the full-scale tornado and the swirl ratio of the field tornado as well as the length and velocity scales of the ...
Proceedings of the XV Conference of the Italian Association for Wind Engineering, 2019
In the context of the European Project THUNDERR a scientific collaboration between the Wind Engin... more In the context of the European Project THUNDERR a scientific collaboration between the Wind Engineering and Structural Dynamics (Windyn) Research Group of the University of Genoa (Italy) and the Wind Engineering, Energy and Environment (WindEEE) Research Institute of Western University (Canada) has been established to study experimentally at the WindEEE Dome facility how the main geometrical and mechanical properties of downbursts are affected by different cloud base outflows of stationary thunderstorms. At present, the analysis of the downbursts simulated experimentally is ongoing and some preliminary elaborations have been obtained concerning the qualitative and quantitative interpretation of the corresponding signals. Classical signal decomposition was applied to experimentally produced downbursts in the WindEEE Dome in order to study transient features of the time series. This study presents the results for two radial positions from downdraft centre and for twenty repetitions per radial position. Several prospects for further research are also discussed.
Separating oil from solid particles is of great importance in many industrial processes including... more Separating oil from solid particles is of great importance in many industrial processes including the extraction of bitumen from oil sands, and the remediation of oil spills. The usual approach is to separate the oil from the solid by introducing another liquid (e.g. water). Separation is often assisted by fluid mixing, and chemical addition. Yet while oil-water-particle separation has been well studied from a chemical standpoint, little research has taken into account the effect of hydrodynamics on separation. In this work, the separation of oil from a single oil-coated spherical particle falling through an aqueous solution was evaluated as a function of viscosity ratio. Solvents were used to modify the viscosity of the oil. The experiments were recorded using a high-speed camera and post-processed using the MATLAB image-processing toolbox. A CFD model has also been developed to study this phenomenon. The results indicate that when viscous forces are strong enough, the oil film deforms, flows to the back of the sphere, and forms a tail that eventually breaks up into a series of droplets due to a capillary wave instability. When the viscosity ratio is small (i.e. the oil is less viscous than the solution), a thin tail forms quickly, the growth rate of the instability is high, and hence the tail breaks very quickly into smaller droplets. When the viscosity ratio is high (i.e. the oil is more viscous), more time is required for the deformation/separation to initiate, and the tail is thicker and breaks more slowly into larger droplets. It was observed that when the viscosity ratio is close to 1, the rate of separation is increased and maximum separation is achieved.
Wind and Structures, 2019
For several decades now experimental fluid mechanics has been relying on classical techniques mai... more For several decades now experimental fluid mechanics has been relying on classical techniques mainly harboured by wind tunnels to deal with mostly canonical problems and therefore have lagged behind the newer computational fluid dynamics advances with applications to multiscale, multi-physics fluid phenomena closer to real life complexities.
Downburst is an anti-tornado system with a slow rotating column of air slowly descending towards ... more Downburst is an anti-tornado system with a slow rotating column of air slowly descending towards the ground which occurs due to the sudden downfall of air and precipitation generated from the cumulonimbus cloud. This natural event produces a strong downdraft which induces an outburst of damaging winds on or near the ground. This radially divergent wind with high velocity transpires when descending air strikes the ground which can cause immense damage to the ground mounted objects and structures. This paper discusses the wind flow characteristics of downbursts produced in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University, Canada. Downdraft diameter and speed were varied to produce several downbursts like flow. Point measurements using Cobra probes and surface measurements using Particle Image Velocimetry (PIV) were performed to analyze the wind flow field in detail. Instantaneous downburst wind speeds were decomposed into slowly varying mean and residual fluctuations for different averaging time. Velocity profile with height from WindEEE was compared with previous experiments and full scale data.
Journal of Fluids and Structures, Nov 1, 2019
h i g h l i g h t s • Adaptation of Davenport Chain to non-synoptic winds. • Properties of three-... more h i g h l i g h t s • Adaptation of Davenport Chain to non-synoptic winds. • Properties of three-dimensional, non-stationary, and non-Gaussian winds. • Climatology, Surface layer, Building aerodynamics effects. • Simulation and scaling of non-synoptic winds.
Environmental Research Letters, Sep 1, 2017
Journal of Wind Engineering and Industrial Aerodynamics, Jun 1, 2016
Abstract Aerodynamic loads on, and wind flow field around, an array of ground mounted solar photo... more Abstract Aerodynamic loads on, and wind flow field around, an array of ground mounted solar photovoltaic (PV) panels, immersed in the atmospheric boundary layer (ABL) for open country exposure, are investigated using the unsteady Reynolds-Averaged Navier–Stokes (RANS) approach. A full scale three-dimensional (3D) solver from OpenFOAM ® (ESI Group) is employed with the Shear Stress Transport (SST) k–ω turbulence closure. Several azimuthal wind directions (South, 0°; Southwest, 45°; Northwest, 135° and North, 180°), for a Reynolds number of 3×10 6 , are considered. The numerical modeling approach is validated by comparing the velocity field surrounding a ground mounted stand-alone solar panel with wind tunnel experiments. Detail analysis of wind loading on the array is provided in relation to the wind flow field surrounding the array. The results for the array configuration show that all the trailing rows are in the complete wake of the leading row for straight winds (0° and 180°), but not for oblique winds (45° and 135°). For all four wind directions studied here, the first windward row experiences the maximum wind loads in terms of drag and lift. In terms of the maximum overturning moment, the 45° and 135° wind directions are critical with similar overturning moment coefficients for each row.
Journal of Wind Engineering and Industrial Aerodynamics, May 1, 2019
Journal of Web Engineering, Jul 14, 2006
Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental ... more Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental results for one swirl ratio: S = 0.28. The simulations are then extended for higher swirl ratio and the variability of the macro-flow dynamics is observed. For lower swirl a laminar surface vortex forms which then breaks-up aloft into a turbulent vortex which with increasing swirl descends towards the surface.
Performance levels and acceptance criteria for wind hazards 29 Performance levels and acceptance ... more Performance levels and acceptance criteria for wind hazards 29 Performance levels and acceptance criteria for buildings subject to coastal inundation Measurement of windstorm resilience and benefits of performance-based design 30 Sound engineering basis for flood resistant design that is not based on flood insurance requirements Analysis procedures for nonlinear system behavior used in performance-based design Cyber-based tools to support performance-based design Legend: Highest priority R&D topic; High priority R&D topic; Medium priority R&D topic GCR 14-973-13 1: Introduction 1-1 Chapter 1 1 As defined by NIST, the term measurement science includes "the development of performance metrics, measurement methods, predictive tools, and protocols as well as reference materials, data, and artifacts; the conduct of inter-comparison studies and calibrations; the evaluation and/or assessment of technologies, systems, and practices; and, the development and/or dissemination of technical guidelines and basis for standards, codes, and practices-in many instances via test beds, consortia, and/or other partnerships with the private sector." 2 Fatality and property loss figures developed from data published by the National Oceanic and Atmospheric Administration (NOAA, 2013a) GCR 14-973-13 4: Recommended Research and Development Topics 4-1 Chapter 4 Recommended Research and Development Topics 4.1
A characterization of mean and turbulent flow behaviour over complex topography was conducted usi... more A characterization of mean and turbulent flow behaviour over complex topography was conducted using a largescale (1:25) model of Bolund Hill in the WindEEE Dome at Western University. The specific topographic feature considered was an escarpment. A total of eight unique inflow conditions were tested in order to isolate the impact of key parameters such as Reynolds number, inflow shear profile and upstream effective roughness, on flow behaviour over the escarpment. The results show that the mean flow behaviour was generally not affected by the Reynolds number, however a slight increase in speed-up over the escarpment was observed for cases with lower upstream roughness. The shape of the inflow wind shear profile also had a minor impact on the mean flow near the escarpment. More significant effects were observed in the turbulent flow behaviour, where the turbulent kinetic energy (TKE) over the escarpment was found be a strong function of upstream roughness and a weak function of the Reynolds number. The local change in the upstream wind shear was found to have the most significant influence on the TKE magnitude, which more closely approximated the full-scale TKE data, and had not been previously observed in wind tunnel modelling of this topography. 1 Introduction Wind turbines over the last few decades have emerged as a reliable and cost-competitive means of producing clean, renewable electricity. Although typically built on relatively flat terrain such as plains and farmland, wind farms are increasingly being placed in more rugged, or complex, terrain, marked by abrupt changes in elevation (Palma et al., 2008). These sites often have strong wind resources, yet designing wind farms for these regions involves additional challenges due to the changes imposed by the terrain on the three-dimensional structure of the wind, such as speed-up regions, changes to the wind shear profile, large vertical wind velocities, and modification of turbulence characteristics (Walmsley and Taylor, 1996; Botta et al., 1998). As a result, the essential prediction of on-site wind conditions, often estimated from measurements at a limited number of mast locations, also becomes more challenging. The use of linearized models, the current industry standard for wind resource assessment and turbine micro-siting, proven to be very effective in gently sloping
In this study, the possibility of simulating some transient and deterministic extreme operational... more In this study, the possibility of simulating some transient and deterministic extreme operational conditions for horizontal axis wind turbines based on the IEC 61400-1 standard in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University was investigated. There are 60 fans (a matrix of 4 by 15 with 0.8m diameter each) on one of the walls of this hexagonal wind tunnel for creating straight flows which the power set-points for each fan can be specified individually. In addition, these fans have adjustable Inlet Guiding Vanes (IGV) that can be controlled uniformly across all of the fans. Using these capabilities, experiments were carried out for the Extreme Operational Gust (EOG), positive and negative Extreme Vertical Shear (EVS), and Extreme Horizontal Shear (EHS) cases, tailored for a 2.2 m HAWT scaled turbine. This study started by developing a numerical model for the test chamber, then using it to tune the fan setups for each extreme condition with proper scaling. Physical experiments then carried out using those settings, then a comparison made between the flow field time history and the prescribed conditions from the standard. The comparisons show promising results, this can be a contribution to future scholars investigating the interaction of the HAWT with these conditions in physical experiments.
Wind Energy Science, 2021
The power generation and loading dynamic responses of a 2.2 m diameter horizontal axis wind turbi... more The power generation and loading dynamic responses of a 2.2 m diameter horizontal axis wind turbine (HAWT) under some of the IEC 61400-1 transient extreme operational conditions, more specifically extreme wind shears (EWSs) and extreme operational gust (EOG), that were reproduced at the WindEEE Dome at Western University were investigated. The global forces were measured by a multi-axis force balance at the HAWT tower base. The unsteady horizontal shear induced a significant yaw moment on the rotor with a dynamic similar to that of the extreme event without affecting the power generation. The EOG severely affected all the performance parameters of the turbine.
Wind Energy Science, 2020
In this study, the possibility of simulating some transient and deterministic extreme operational... more In this study, the possibility of simulating some transient and deterministic extreme operational conditions for horizontal axis wind turbines based on the IEC 61400-1 standard using 60 individually controlled fans in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University was investigated. Experiments were carried out for the extreme operational gust (EOG), positive and negative extreme vertical shear (EVS), and extreme horizontal shear (EHS) cases, tailored for a scaled 2.2 m horizontal axis wind turbine. For this purpose, firstly a numerical model for the test chamber was developed and used to obtain the fans' configurations for simulating each extreme condition with appropriate scaling prior to the physical experiments. The results show the capability of using numerical modelling to predict the fans' setup based on which physical simulations can generate IEC extreme conditions in the range of interest.
Wind Energy Science Discussions, 2016
A characterization of mean and turbulent flow behaviour over complex topography was conducted usi... more A characterization of mean and turbulent flow behaviour over complex topography was conducted using a large-scale (1:25) model of Bolund Hill in the WindEEE Dome at Western University. The specific topographic feature considered was an escarpment. A total of eight unique inflow conditions were tested in order to isolate the impact of key parameters such as Reynolds number, inflow shear profile and upstream effective roughness, on flow behaviour over the escarpment. <br><br> The results show that the mean flow behaviour was generally not affected by the Reynolds number, however a slight increase in speed-up over the escarpment was observed for cases with lower upstream roughness. The shape of the inflow wind shear profile also had a minor impact on the mean flow near the escarpment. More significant effects were observed in the turbulent flow behaviour, where the turbulent kinetic energy (TKE) over the escarpment was found be a strong function of upstream roughness and a ...
Jwe 日本風工学研究会誌, Jul 14, 2006
Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental ... more Three-dimensional RANS simulations of tornado-like vortices are benchmarked against experimental results for one swirl ratio: S = 0.28. The simulations are then extended for higher swirl ratio and the variability of the macro-flow dynamics is observed. For lower swirl a laminar surface vortex forms which then breaks-up aloft into a turbulent vortex which with increasing swirl descends towards the surface.
Particle Image Velocimetry (PIV) technique was employed to characterize the flow field of simulat... more Particle Image Velocimetry (PIV) technique was employed to characterize the flow field of simulated tornado vortices and to establish a relationship between laboratory generated tornadoes and the field ones. Field data collected by mobile Doppler radars were analyzed using a mathematical method namely the Ground-based Velocity Track Display (GBVTD) and the velocity fields were extracted. The horizontal velocity field of tornado vortices, simulated in Model WindEEE Dome, was measured using PIV for a wide range of vortex intensity. The substantial mismatch between the averaging time of the full-scale data and the laboratory data which is originated in the very small length scale of the simulation and the low sampling rate of the PIV system, was addressed and corrected using the Durst curve. Once modified, the velocity field of the simulated vortex was compared with that of the full-scale tornado and the swirl ratio of the field tornado as well as the length and velocity scales of the ...
Proceedings of the XV Conference of the Italian Association for Wind Engineering, 2019
In the context of the European Project THUNDERR a scientific collaboration between the Wind Engin... more In the context of the European Project THUNDERR a scientific collaboration between the Wind Engineering and Structural Dynamics (Windyn) Research Group of the University of Genoa (Italy) and the Wind Engineering, Energy and Environment (WindEEE) Research Institute of Western University (Canada) has been established to study experimentally at the WindEEE Dome facility how the main geometrical and mechanical properties of downbursts are affected by different cloud base outflows of stationary thunderstorms. At present, the analysis of the downbursts simulated experimentally is ongoing and some preliminary elaborations have been obtained concerning the qualitative and quantitative interpretation of the corresponding signals. Classical signal decomposition was applied to experimentally produced downbursts in the WindEEE Dome in order to study transient features of the time series. This study presents the results for two radial positions from downdraft centre and for twenty repetitions per radial position. Several prospects for further research are also discussed.
Separating oil from solid particles is of great importance in many industrial processes including... more Separating oil from solid particles is of great importance in many industrial processes including the extraction of bitumen from oil sands, and the remediation of oil spills. The usual approach is to separate the oil from the solid by introducing another liquid (e.g. water). Separation is often assisted by fluid mixing, and chemical addition. Yet while oil-water-particle separation has been well studied from a chemical standpoint, little research has taken into account the effect of hydrodynamics on separation. In this work, the separation of oil from a single oil-coated spherical particle falling through an aqueous solution was evaluated as a function of viscosity ratio. Solvents were used to modify the viscosity of the oil. The experiments were recorded using a high-speed camera and post-processed using the MATLAB image-processing toolbox. A CFD model has also been developed to study this phenomenon. The results indicate that when viscous forces are strong enough, the oil film deforms, flows to the back of the sphere, and forms a tail that eventually breaks up into a series of droplets due to a capillary wave instability. When the viscosity ratio is small (i.e. the oil is less viscous than the solution), a thin tail forms quickly, the growth rate of the instability is high, and hence the tail breaks very quickly into smaller droplets. When the viscosity ratio is high (i.e. the oil is more viscous), more time is required for the deformation/separation to initiate, and the tail is thicker and breaks more slowly into larger droplets. It was observed that when the viscosity ratio is close to 1, the rate of separation is increased and maximum separation is achieved.
Wind and Structures, 2019
For several decades now experimental fluid mechanics has been relying on classical techniques mai... more For several decades now experimental fluid mechanics has been relying on classical techniques mainly harboured by wind tunnels to deal with mostly canonical problems and therefore have lagged behind the newer computational fluid dynamics advances with applications to multiscale, multi-physics fluid phenomena closer to real life complexities.
Downburst is an anti-tornado system with a slow rotating column of air slowly descending towards ... more Downburst is an anti-tornado system with a slow rotating column of air slowly descending towards the ground which occurs due to the sudden downfall of air and precipitation generated from the cumulonimbus cloud. This natural event produces a strong downdraft which induces an outburst of damaging winds on or near the ground. This radially divergent wind with high velocity transpires when descending air strikes the ground which can cause immense damage to the ground mounted objects and structures. This paper discusses the wind flow characteristics of downbursts produced in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University, Canada. Downdraft diameter and speed were varied to produce several downbursts like flow. Point measurements using Cobra probes and surface measurements using Particle Image Velocimetry (PIV) were performed to analyze the wind flow field in detail. Instantaneous downburst wind speeds were decomposed into slowly varying mean and residual fluctuations for different averaging time. Velocity profile with height from WindEEE was compared with previous experiments and full scale data.
Journal of Fluids and Structures, Nov 1, 2019
h i g h l i g h t s • Adaptation of Davenport Chain to non-synoptic winds. • Properties of three-... more h i g h l i g h t s • Adaptation of Davenport Chain to non-synoptic winds. • Properties of three-dimensional, non-stationary, and non-Gaussian winds. • Climatology, Surface layer, Building aerodynamics effects. • Simulation and scaling of non-synoptic winds.
Environmental Research Letters, Sep 1, 2017
Journal of Wind Engineering and Industrial Aerodynamics, Jun 1, 2016
Abstract Aerodynamic loads on, and wind flow field around, an array of ground mounted solar photo... more Abstract Aerodynamic loads on, and wind flow field around, an array of ground mounted solar photovoltaic (PV) panels, immersed in the atmospheric boundary layer (ABL) for open country exposure, are investigated using the unsteady Reynolds-Averaged Navier–Stokes (RANS) approach. A full scale three-dimensional (3D) solver from OpenFOAM ® (ESI Group) is employed with the Shear Stress Transport (SST) k–ω turbulence closure. Several azimuthal wind directions (South, 0°; Southwest, 45°; Northwest, 135° and North, 180°), for a Reynolds number of 3×10 6 , are considered. The numerical modeling approach is validated by comparing the velocity field surrounding a ground mounted stand-alone solar panel with wind tunnel experiments. Detail analysis of wind loading on the array is provided in relation to the wind flow field surrounding the array. The results for the array configuration show that all the trailing rows are in the complete wake of the leading row for straight winds (0° and 180°), but not for oblique winds (45° and 135°). For all four wind directions studied here, the first windward row experiences the maximum wind loads in terms of drag and lift. In terms of the maximum overturning moment, the 45° and 135° wind directions are critical with similar overturning moment coefficients for each row.
Journal of Wind Engineering and Industrial Aerodynamics, May 1, 2019