Establishing a Comprehensive Wind Energy Program

This project was directed at establishing a comprehensive wind energy program in Indiana, including both educational and research components. A graduate/undergraduate course ME-514 - Fundamentals of Wind Energy has been established and offered and an interactive prediction of VAWT performance developed. Vertical axis wind turbines for education and research have been acquired, instrumented and installed on the roof top of a building on the Calumet campus and at West Lafayette (Kepner Lab). Computational Fluid Dynamics (CFD) calculations have been performed to simulate these urban wind environments. Also, modal dynamic testing of the West Lafayette VAWT has been performed and a novel horizontal axis design initiated. The 50-meter meteorological tower data obtained at the Purdue Beck Agricultural Research Center have been analyzed and the Purdue Reconfigurable Micro Wind Farm established and simulations directed at the investigation of wind farm configurations initiated. The virtual wind turbine and wind turbine farm simulation in the Visualization Lab has been initiated

The Air-temperature Response to Green/blue-infrastructure Evaluation Tool (TARGET v1.0) : an efficient and user-friendly model of city cooling

The adverse impacts of urban heat and global climate change are leading policymakers to consider green and blue infrastructure (GBI) for heat mitigation benefits. Though many models exist to evaluate the cooling impacts of GBI, their complexity and computational demand leaves most of them largely inaccessible to those without specialist expertise and computing facilities. Here a new model called The Air-temperature Response to Green/blue-infrastructure Evaluation Tool (TARGET) is presented. TARGET is designed to be efficient and easy to use, with fewer user-defined parameters and less model input data required than other urban climate models. TARGET can be used to model average street-level air temperature at canyon-to-block scales (e.g. 100 m resolution), meaning it can be used to assess temperature impacts of suburb-to-city-scale GBI proposals. The model aims to balance realistic representation of physical processes and computation efficiency. An evaluation against two different datasets shows that TARGET can reproduce the magnitude and patterns of both air temperature and surface temperature within suburban environments. To demonstrate the utility of the model for planners and policymakers, the results from two precinct-scale heat mitigation scenarios are presented. TARGET is available to the public, and ongoing development, including a graphical user interface, is planned for future work

Performance of a Savonius wind turbine in urban sites using CFD analysis

fi=vertaisarvioitu|en=peerReviewed

Urban Climate Under Change [UC]2 – A National Research Programme for Developing a Building-Resolving Atmospheric Model for Entire City Regions

Large cities and urban regions are confronted with rising pressure by environmental pollution, impacts of climate change, as well as natural and health hazards. They are characterised by heterogeneous mosaics of urban structures, causing modifications of atmospheric processes on different temporal and spatial scales. Planning authorities need reliable, locally relevant information on urban atmospheric processes, providing fine spatial resolutions in city quarters or street canyons, as well as projections of future climates, specifically downscaled to individual cities. Therefore, building-resolving urban climate models for entire city regions are required as tool for urban development and planning, air quality control, as well as for design of actions for climate change mitigation and adaptation. To date, building-resolving atmospheric models covering entire large cities are mostly missing. The German research programme “Urban Climate Under Change” ([UC]2) aims at developing a new urban climate model, to acquire three-dimensional observational data for model testing and validation, and to test its practicability and usability in collaboration with relevant stakeholders to provide a scientifically sound and practicable instrument to address the above mentioned challenges. This article provides an outline of the collaborative activities of the [UC]2 research programme

Modeling of plume dispersion and interaction with the surround of synthetic imaging applications

Discharge of effluent gas is an inescapable byproduct of many physical processes. The type or characteristics of the discharge potentially indicate the nature of the process. Observation of factory stack gases, for example, may indicate the level of pollutants being emitted into the atmosphere or the nature of the process being carried out in the factory. In this work, we have developed an improved model of plume dispersion suitable for synthetic image generation (SIG) applications. The technique partially utilizes a new EPA model that discretizes the plume into a series of small puffs (rather than the implicit mono lithic form used in prior regulatory and SIG work) . The locations and sizes of these puffs are then perturbed to approximate the location and size of the plume at any given instant and to incorporate the effects of high-frequency wind fluctuation. We have incorporated an improved model for plume temperature calculation and a more accurate method for calculating the aggregate self-emitted radiance for rays traced through the plume. We have also developed novel techniques simulating the interaction of plumes with their surroundings. Our primary application of this work is the simulation of heating of roofs by vents of various types. The technique can also be used to simulate vehicle exhaust and other similar effects. Finally, we have established a protocol for future modification of plume calculation algorithms by end-users of the Digital Imaging and Remote Sensing Image Generation (DIRSIG) code and implemented the present methods as prototypes. This Generic Plume Interface (GPI) protocol defines a message set used to request that the plume effect along a particular ray be calculated and to communicate back to DIRSIG the concentrations and temperatures along the ray. With this construct in place, any off-the-shelf tool can be interfaced with DIRSIG through a simple user-written interpreter to make appropriate inputs to the tool for each ray and to translate the output into the proper format

Employing 2-D CFD & LRB Model Around Trees to Improve VAWT Placement

In the placement of vertical axis wind turbines, trees are a constant presence in the vicinity. They are found to grow at different height and shape configurations. And in areas such as the Minnesota State University, Mankato (MNSU) campus, they serve as blockage to airflow; limiting the efficiency of installed turbines. This work sets the precedent for the validation of vegetative numerical models created for the Xcel Energy Research Development Fund (RDF) project. Using two-dimensional (2-D) numerical simulations of porous cylinders placed in a rectangular medium of air, insight into the flow profile and distribution in the leeward side of the cylinder is gained. Mesh and turbulence intensity dependency test show less than 5% change in flow properties. Domain size and blockage ratio remained an important factor to consider during this simulation. In this work, a numerical investigation was performed using design of experiment (DOE) principles, atmospheric flow and VAWT performance criteria to vary the incoming velocity and porosity to observe the effect on the wake velocity characteristics. It was observed that for inertial resistance coefficients greater than 200 m-1, the porous cylinder behaves as an impermeable object limiting the flow of air through the porous zone. Following the qualitative descriptions of the porous flow regime, comparisons are made with 2-D results from existing literature. For velocity, there is strong agreement with trend of the non-dimensional velocity flow along the centerline. However, the results from the pressure distribution and the turbulent properties are underestimated when compared due to the presence of enstrophy in 3-D flow. Using actuator disk theory and leaky Rankine bodies, the resulting velocity field is used to obtain an estimate of source and sink strength ratios for use in flow field estimation

Master of Science

thesisThe Quick Urban and Industrial Complex (QUIC) dispersion modeling system has been developed to calculate wind and concentration fi elds in cities with buildings explicitly resolved. As opposed to other models which are either limited to a simpli ed gaussian plume without buildings or are computationally expensive and take weeks to grid and solve. The focus of this paper is a new data assimilation technique that improves QUIC-URB, a fast response three-dimensional (3D) diagnostic urban wind model. The QUIC-URB modeling system discussed in this paper was adapted from a previous version, which initialized the flow fi eld with horizontally uniform velocities based on wind speed and wind direction information obtained from a single measurement upwind of an urban area. Previous urban studies have shown that cities are often subject to large scale spatially varying in flows. To account for this spatial heterogeneity, a simple Quasi-3D Barnes Objective Map Analysis Scheme (a Gaussian weighted averaging technique), which initializes the flow fi eld based on multiple sensors and soundings located around the urban area has been implemented. This wind field is then modi ed by QUIC-URB's empirical building flow parameterizations to model the flow around individual buildings. The fi nal flow field is then obtained by ensuring mass conservation. This work is a validation of this multisensor data assimilation QUIC-URB model. The analysis shows QUIC-URB solutions compared to results of a hybrid Reynolds Averaged Navier-Stokes (RANS) solution of the same urban environment using the commercial Computational Fluid Dynamic (CFD) solver, FLUENT. Nine individual vertical velocity profi les located around the urban area are extracted from the FLUENT data set to simulate soundings around three urban environments consisting of an array of containers and three di fferent sizes of flow altering topographies. These velocity profi les are used as input profi les for QUIC-URB's new initialization scheme. The fi nal wind fi elds from QUIC-URB and FLUENT are qualitatively and quantitatively compared. The initial implementation of this data assimilation technique captures the gross eff ects of nonuniform mean wind fi elds around urban areas well. However, there are def ciencies when ingesting localized ow. The local flow eff ects of buildings and other relatively small geometries are spread out beyond their applicable region when input data is sparse. Limiting these localized eff ects to their applicable regions is an area for future research

Wind prediction modelling and validation using coherent Doppler LIDAR data

A physically-based wind model is applied to determine wind speed and direction and to conduct a model sensitivity analysis. The model is later coupled with a microclimatic model utilizing a novel technique to support short term forecasting at Lake Turkana Wind Fam site, Kenya. Improved statistical comparisons of wind speed and direction are achieved between the model and in situ observations. Coherent Doppler LIDAR observations agreed well with the microclimatic model

Topology-free immersed boundary method for incompressible turbulence flows: An aerodynamic simulation for 'dirty' CAD geometry

To design a method to solve the issues of handling 'dirty' and highly complex geometries, the topology-free method combined with the immersed boundary method is presented for viscous and incompressible flows at a high Reynolds number. The method simultaneously employs a ghost-cell technique and distributed forcing technique to impose the boundary conditions. An axis-projected interpolation scheme is used to avoid searching failures during fluid and solid identification. This method yields a topology-free immersed boundary, which particularly suits flow simulations of highly complex geometries. Difficulties generally arise when generating the calculation grid for these scenarios. This method allows dirty data to be handled without any preparatory treatment work to simplify or clean-up the geometry. This method is also applicable to the coherent structural turbulence model employed in this study. The verification cases, used in conjunction with the second-order central-difference scheme, resulted in first-order accuracy at finer resolution, although the coarser resolution retained second-order accuracy. This method is fully parallelized for distributed memory platforms. In this study, the accuracy and fidelity of this method were examined by simulating the flow around the bluff body, past a flat plate, and past dirty spheres. These simulations were compared with experimental data and other established results. Finally, results from the simulation of practical applications demonstrate the ability of the method to model highly complex, non-canonical three-dimensional flows. The countermeasure based on the accurate classification of geometric features has provided a robust and reasonable solution.Comment: 33 pages, 23 figure