scholarly journals Hydrodynamic impact and power production of tidal turbines in a storm surge barrier

2020 ◽  
Vol 3 (3) ◽  
pp. 127-136
Author(s):  
Thomas O'Mahoney ◽  
Anton De Fockert ◽  
Arnout C. Bijlsma ◽  
Pieter De Haas
Keyword(s):  
Storm Surge ◽  
Energy Production ◽  
Field Experiments ◽  
Turbine Blades ◽  
Cfd Model ◽  
Hydrodynamic Impact ◽  
Tidal Turbines ◽  
Gate Opening ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

To estimate the impact on energy production and environment of tidal turbines placed in the Eastern Scheldt Storm Surge Barrier a Computational Fluid Dynamics (CFD) study has been carried out on the additional head differences induced by the turbines. The CFD model focusses on a single gate opening of the Storm Surge Barrier and includes half of the adjoining gates on either side. In this 40 m wide Gate a 1.2 MW array existing of five Tocardo T2 tidal turbines has been installed as part of a demonstration project in 2015. Transient computations of the barrier with and without the turbine array were carried out for a range of quasi stationary tidal phases. The turbines are resolved in detail as rotating equipment: real-time rotation of the turbine blades (involving the displacement of the mesh nodes in an unsteady setting) is implemented, and torque and thrust for the prescribed speed of rotation is provided as output. The results for velocity, power and thrust are compared with field experiments to validate the model. Based on these computations an estimate of the effect of turbines on the discharge capacity of the storm surge barrier is given. This information will be used to parameterize the tidal turbines in the far-field hydrodynamic model of Eastern Scheldt estuary for the ultimate assessment of the effect of tidal turbines on energy production and on the environment.

CFD Study on Free-Surface Influence on Tidal Turbines in Hydraulic Structures

2015 ◽  
Author(s):  
Aldo Tralli ◽  
Arnout C. Bijlsma ◽  
Wilbert te Velde ◽  
Pieter de Haas
Keyword(s):  
Free Surface ◽  
Storm Surge ◽  
Field Measurements ◽  
Hydraulic Structures ◽  
Generic Structure ◽  
Tidal Turbines ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Method Model ◽  
Blade Element

In order to estimate the impact on energy production and environment of tidal turbines placed in or near hydraulic structures like discharge sluices or storm surge barriers, a Computational Fluid Dynamics (CFD) study has been carried out on the relation between (head) loss induced by the turbines and their gross power production. CFD computations have been performed for Tocardo T2 turbines, using STAR-CCM+. Simulations of a single turbine in free flow conditions compare favorably with results of Blade Element Momentum (BEM) computations, in terms of torque and thrust. This BEM method model had been previously validated against both CFD data and field measurements. Then, a series of tests has been performed in a “virtual tow tank”, including the effect of the free surface and the blockage by side and bottom walls. These computations provide a base for a first estimate of the effect of turbines on the discharge capacity of a generic structure. This is considered to be the first step in a more general approach in which ultimately the effect of tidal turbines in the Eastern Scheldt Storm Surge Barrier will be assessed.

scholarly journals Uncertainty Quantification of Leakages in a Multistage Simulation and Comparison With Experiments

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Cosimo Maria Mazzoni ◽  
Richard Ahlfeld ◽  
Budimir Rosic ◽  
Francesco Montomoli
Keyword(s):  
Uncertainty Quantification ◽  
Numerical Study ◽  
Turbine Blades ◽  
Industrial Practice ◽  
Turbine Efficiency ◽  
Simulation Based ◽  
Multistage Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Yaw Angle ◽  
The Impact

This paper presents a numerical study of the impact of tip gap uncertainties in a multistage turbine. It is well known that the rotor gap can change the gas turbine efficiency, but the impact of the random variation of the clearance height has not been investigated before. In this paper, the radial seals clearance of a datum shroud geometry, representative of steam turbine industrial practice, was systematically varied and numerically tested by means of unsteady computational fluid dynamics (CFD). By using a nonintrusive uncertainty quantification (UQ) simulation based on a sparse arbitrary moment-based approach, it is possible to predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exit of the turbine blades. This work shows that the impact of gap uncertainties propagates radially from the tip toward the hub of the turbine, and the complete span is affected by a variation of the rotor tip gap. This amplification of the uncertainty is mainly due to the low-aspect ratio of the turbine, and a similar behavior is expected in high pressure (HP) turbines.

Impact of Heat Transfer on Contaminant Dispersion in a Public Building

2006 ◽  
Author(s):  
Sue Ellen Haupt ◽  
Robert F. Kunz ◽  
L. Joel Peltier ◽  
James J. Dreyer ◽  
Howard J. Gibeling
Keyword(s):  
Thermal Effects ◽  
Building Materials ◽  
Time Of Day ◽  
Thermal Coupling ◽  
Cfd Model ◽  
Thermal Heating ◽  
Contaminant Dispersion ◽  
Cfd Models ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

Computational fluid dynamics (CFD) models are effective at predicting dispersion of contaminants in or near a building. It is well known that thermal effects impact the flow around and within structures. This study assesses the importance of time of day, building materials, sky cover, etc. on the local thermal heating of a building. All these features affect the buoyancy, and thus, the resulting flow and dispersion about and inside a building. This study examines that impact through including full thermal coupling with flow calculations for an environmentally friendly building, including thermal radiation, conduction, and convection effects with a CFD model for both the interior and exterior of a building. The emphasis here is on simulating the impact of heating on contaminant dispersion.

scholarly journals Linking urban aerosol fluxes in street canyons to larger scale emissions

2010 ◽  
Vol 10 (5) ◽  
pp. 2475-2490 ◽  
Author(s):  
B. K. Tay ◽  
G. B. McFiggans ◽  
D. P. Jones ◽  
M. W. Gallagher ◽  
C. Martin ◽  
...  
Keyword(s):  
Eddy Viscosity ◽  
Field Experiments ◽  
Ultrafine Particle ◽  
Urban Aerosol ◽  
Cfd Model ◽  
Street Canyons ◽  
First Order ◽  
Flux Measurements ◽  
Circulatory Flow ◽  
Computational Fluid Dynamics Cfd

Abstract. In this study we investigate ultrafine particle (UFP) fluxes using a first order eddy viscosity turbulence closure Computational Fluid Dynamics (CFD) model and determine the different factors that influence emissions of UFP into the urban boundary layer. Both vertical turbulent fluxes as well as the fluxes due to mean circulatory flow are shown to contribute to the overall ventilation characteristics of street canyons. We then derive a simple parameterised numerical prediction model for canyon top UFP venting which is then compared with tower based micrometeorological flux measurements obtained during the REPARTEE & CityFlux field experiments.

The Reduction of Over Tip Leakage Loss in Unshrouded Axial Turbines Using Winglets and Squealers

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Zbigniew Schabowski ◽  
Howard Hodson
Keyword(s):  
Flow Pattern ◽  
Large Scale ◽  
Turbine Blades ◽  
Suction Side ◽  
Leakage Loss ◽  
Tip Leakage ◽  
Gap Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Axial Turbines ◽  
The Impact

The possibilities of reducing the over tip leakage loss of unshrouded rotors have been investigated using a linear cascade of turbine blades and computational fluid dynamics (CFD). The large-scale blade profile is the same as that of the tip profile of a low-speed high-pressure research turbine facility. The impact of various combinations of squealer and winglet geometries on the turbine performance has been investigated. The influence of the thickness of the squealers has also been assessed. It was found that a 22% reduction in loss slope was possible, when compared to the flat tip blade, using simple tip modifications. The results obtained with the suction side squealer and cavity tip agreed well with the work of other researchers. Three winglet-based tip geometries were tested. One was a plain winglet, the other two had squealers applied. A significant impact of the squealers and their shape on the tip gap flow pattern and loss generation was found. The physical processes occurring within the tip gap region for the tested geometries are explained using both numerical and experimental results. The impact of the flow pattern within the tip gap on the loss generation is described. Good agreement between CFD and the experimental data was found. This shows that CFD can be used with confidence in the design process of shroudless turbines.

scholarly journals Partial integration of ADM1 into CFD: understanding the impact of diffusion on anaerobic digestion mixing

2020 ◽  
Vol 81 (8) ◽  
pp. 1658-1667 ◽  
Author(s):  
Yohannis Mitiku Tobo ◽  
Usman Rehman ◽  
Jan Bartacek ◽  
Ingmar Nopens
Keyword(s):  
Anaerobic Digestion ◽  
Homogeneous Distribution ◽  
Cfd Model ◽  
Homogeneity Analysis ◽  
Cfd Models ◽  
Mode Of Operation ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Proper Performance ◽  
Partial Integration

Abstract Sufficient mixing is crucial for the proper performance of anaerobic digestion (AD), creating a homogeneous distribution of soluble substrates, biomass, pH, and temperature. The opaqueness of the sludge and mode of operation make it challenging to study AD mixing experimentally. Therefore, hydrodynamics modelling employing computational fluid dynamics (CFD) is often used to investigate this mixing. However, CFD models mostly do not include biochemical reactions and, hence, ignore the effect of diffusion-induced transport on AD heterogeneity. The novelty of this work is the partial integration of Anaerobic Digestion Model no. 1 (ADM1) into the CFD model. The aim is to better understand the effect of advection–diffusion transport on the homogenization of soluble substrates and biomass. Furthermore, AD homogeneity analysis in terms of concentration distribution is proposed rather than the traditional velocity distributions. The computed results indicate that including diffusion-induced transport affects the homogeneity of AD.

scholarly journals Linking aerosol fluxes in street canyons to urban city-scale emissions

2009 ◽  
Vol 9 (5) ◽  
pp. 18065-18112
Author(s):  
B. K. Tay ◽  
G. B. McFiggans ◽  
D. P. Jones ◽  
M. W. Gallagher ◽  
C. Martin ◽  
...  
Keyword(s):  
Eddy Viscosity ◽  
Field Experiments ◽  
Ultrafine Particle ◽  
Cfd Model ◽  
Mean Flow ◽  
Street Canyons ◽  
First Order ◽  
Urban City ◽  
Flux Measurements ◽  
Computational Fluid Dynamics Cfd

Abstract. In this study we investigate ultrafine particle (UFP) fluxes using a first order eddy viscosity turbulence closure Computational Fluid Dynamics (CFD) model and determine the different factors that influence emissions of UFP into the urban boundary layer. Both vertical turbulent fluxes as well as the fluxes due to mean flow are shown to contribute to the overall ventilation characteristics of street canyons. We then derive a simple parameterised numerical prediction model for canyon top UFP venting which is then compared with tower based micrometeorological flux measurements obtained during the REPARTEE and CityFlux field experiments.

Profiling and modelling of thermal changes in a large waste stabilisation pond

2005 ◽  
Vol 51 (12) ◽  
pp. 163-172 ◽  
Author(s):  
D.G. Sweeney ◽  
J.B. Nixon ◽  
N.J. Cromar ◽  
H.J. Fallowfield
Keyword(s):  
Wind Shear ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Prevailing Wind ◽  
Cfd Model ◽  
Thermal Changes ◽  
Thermal Profiling ◽  
Computational Fluid Dynamics Cfd ◽  
High Degree ◽  
The Impact

A thermal profiling study was undertaken at four depths at each of nine sites, and at the inlets and outlets of a large waste stabilisation pond (WSP). Results were collected simultaneously using a network of 42 thermistors and dataloggers. Profiles at each site were categorised as either “stratified” or “unstratified”, and persistence analysis was used to determine the frequency and persistence of stratification events at each of the nine sites. Stratification was found to persist most strongly at the site furthest upwind in the WSP, with respect to prevailing wind during the study, leading to the conclusion that stratification induced short-circuiting will be greatest in this region of the WSP. A computational fluid dynamics (CFD) model was constructed of the WSP, including an energy balance to predict the bulk stratification gradient in the pond. Environmental conditions and WSP inlet temperature during one day in June 2001 were used as boundary conditions. The pond thermal profiles measured during the profiling study, together with outlet temperature during the day, were used to validate the CFD model results. The model predicted mean pond temperature with a high degree of accuracy (r2=0.92). However it was evident that even modest winds (≥1.5 m/s) partially broke down stratification, leading to poor prediction of the gradient by the CFD model, which did not directly account for the impact of wind shear stress on mixing in the WSP.

INFLUENCE OF THE DIFFERENT SOIL PREPARATION METHODS ON THE PEA YIELD

2018 ◽  
pp. 16-20
Author(s):  
А. М. Grebennikov ◽  
А. S. Frid ◽  
V. P. Belobrov ◽  
V. А. Isaev ◽  
V. М. Garmashоv ◽  
...  
Keyword(s):  
Field Experiments ◽  
Morphological Properties ◽  
Mineral Fertilizers ◽  
First Year ◽  
Zero Tillage ◽  
Preparation Methods ◽  
Soil Preparation ◽  
Multifactor Analysis ◽  
The Impact ◽  
Central Chernozem

The article assesses the relationships between the morphological properties of agrochernozems and yield of peas on the plots, experience with different methods of basic treatment (moldboard plowing at the depth of 20 - 22, 25 - 27 and 14 - 16 cm, moldboard plowing to a depth of 14 - 16 cm, combined midwater moldboard, mid-water subsurface, surface to a depth of 6 - 8 cm and zero tillage) is inherent in V.V. Dokuchaev Research Institute of Agriculture of the Central Black Earth strip, in the fall of 2014. The research was conducted in 2015 - 2016, with the application of mineral fertilizers (N60Р60К60) and unfertilized background. The highest pea yields in the fertilized as the background, and without the use of fertilizers was observed in dumping plowing and especially in the variant with deep moldboard plowing, which creates in comparison with other ways of handling the best conditions for the growth and development of peas. The lowest yield of pea was obtained with zero processing. Apparently legalistic migrational-mizelial agrochernozems the Central Chernozem zone of minimum tillage in the cultivation of peas are not effective, what is evident already in the first year after the laying of experience with different basic treatments. As shown by the results of applying multifactor analysis of variance studied the mapping properties of the soil can have the same significant impact on the yield of agricultural crops, as options for the field experiments aimed at assessing the impact of various treatments on yield.

AMOUNT AND STRUCTURE OF THE BIOLOGICAL FERTILITY OF SOYA, DEPENDING ON THE SYSTEM OF MAIN TILLAGE OF SOIL AND MEASURES TO OPTIMIZE NUTRITION MODE

2020 ◽  
Author(s):  
M. Novokhatskyi ◽  
◽  
V. Targonya ◽  
T. Babinets ◽  
O. Gorodetskyi ◽  
...  
Keyword(s):  
Field Experiments ◽  
Optimal Number ◽  
Soil Tillage ◽  
Forest Steppe ◽  
Biological Productivity ◽  
Tillage Systems ◽  
Application Rates ◽  
Tillage System ◽  
Biological Yield ◽  
The Impact

Aim. Assessment of the impact of the most common systems of basic tillage and biological methods of optimization of nutrition regimes on the realization of the potential of grain productivity of soybean in the Forest-Steppe of Ukraine. Methods. The research used general scientific (hypothesis, experiment, observation) and special (field experiment, morphological analysis) methods Results. The analysis of the results of field experiments shows that the conservation system of soil cultivation, which provided the formation of 27.6 c/ha of grain, is preferable by the level of biological yield of soybean. The use of other systems caused a decrease in the biological yield level: up to 26.4 c/ha for the use of the traditional system, up to 25.3 c/ha for the use of mulching and up to 23.0 c/ha for the use of the mini-till. With the use of Groundfix, the average biological yield of soybean grain increases to 25.6 c / ha for application rates of 5 l/ha, and to 28.2 c/ha for application rates of 10 l/ha when control variants (without the use of the specified preparation) an average of 22.6 c/ha of grain was formed with fluctuations in soil tillage systems from 21.0 (mini-bodies) to 25.8 c/ha (traditional).The application of Groundfix (10 l/ha) reduced the seed abortion rate from 11.0% (average without biofertilizer variants) to 8.0%, forming the optimal number of stem nodes with beans, increasing the attachment height of the lower beans and improving other indicators of biological productivity soybeans. Conclusions. It has been found that the use of the canning tillage system generates an average of 27.6 cent soybean grains, which is the highest indicator among the main tillage systems within the scheme of our research. The use of Groundfix caused a change in this indicator: if the variants with a conservative system of basic tillage without the use of biological preparation (control) were formed on average 24.1 c/ha, the use of Ground Licks caused the increase of biological productivity up to 29.4 c/ha, and at a dose of 10 l/ha biological yield was 32.2 c/ha. It was found that both the use of Groundfix and the basic tillage system influenced the elements of the yield structure: the density of the plants at the time of harvest depended more on the tillage system than on the use of Groundfix; the use of Groundfix and increasing its dose within the scheme of our studies positively reflected on the density of standing plants; the height of attachment of the lower beans and reduced the abortion of the seeds.

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