Abstract: Passive air pollution control devices known as aspiration efficiency reducers (AER) have been developed using aspiration efficiency (AE) concepts. Their purpose is to reduce the concentration of particulate matter (PM) drawn into a building air handling unit (AHU) through alterations in the inlet design improving energy consumption. In this paper an examination is conducted into the effect of installing a deflector system around an AER-AHU inlet for both a forward and rear-facing orientations relative to the wind. The results of the study found that these deflectors are an effective passive control method for reducing AE at various ambient wind speeds over a range of microparticles of varying diameter. The deflector system was found to induce a large wake zone at low ambient wind speeds for a rear-facing AER-AHU, resulting in significantly lower AE in comparison to without. As the wind speed increased, both contained a wake zone but have much lower concentration gradients with the deflectors. For the forward-facing models, the deflector system at low ambient wind speed was preferred at higher Stokes numbers but there was negligible difference as the Stokes number decreased. Similarly, there was no significant difference at higher wind speeds across the Stokes number range tested. The results demonstrate that a deflector system is a viable passive control method for the reduction of ventilation energy consumption.
Abstract: Different approaches have been used to predict the performance of the vertical axis wind turbines (VAWT), such as experimental, computational fluid dynamics (CFD), and analytical methods. Analytical methods, such as momentum models that use streamtubes, have low computational cost and sufficient accuracy. The double multiple streamtube (DMST) is one of the most commonly used of momentum models, which divide the rotor plane of VAWT into upwind and downwind. In fact, results from the DMST method have shown some discrepancy compared with experiment results; that is because the Darrieus turbine is a complex and aerodynamically unsteady configuration. In this study, analytical-experimental-based corrections, including dynamic stall, streamtube expansion, and finite blade length correction are used to improve the DMST method. Results indicated that using these corrections for a SANDIA 17-m VAWT will lead to improving the results of DMST.
Abstract: Building ventilation performance is an important indicator of indoor comfort. However, in addition to the geometry of the building or the proportion of the opening, the ventilation performance is also very much related to the actual wind pressure of the building. There are more and more contemporary building designs built with multi-layer exterior envelope. Due to ventilation and view observatory requirement, the porous outer layer of the building is commonly adopted and has a significant wind damping effect, causing the phenomenon of actual wind pressure loss. However, the relationship between the wind damping effect and the actual wind pressure is not linear. This effect can make the indoor ventilation of the building rationalized to reasonable range under the condition of high wind pressure, and also maintain a good amount of ventilation performance under the condition of low wind pressure. In this study, wind tunnel experiments were carried out to simulate the different wind pressures flow through the porous outer layer, and observe the actual wind pressure strength engage with the window layer to find the decreasing relationship between the damping effect of the porous shell and the wind pressure. Experiment specimen scale was designed to be 1:50 for testing real-world building conditions; the study found that the porous enclosure has protective shielding without affecting low-pressure ventilation. Current study observed the porous skin may damp more wind energy to ease the wind pressure under high-speed wind. Differential wind speed may drop the pressure into similar pressure level by using porous skin. The actual mechanism and value of this phenomenon will need further study in the future.
Abstract: Installation of micro-generators based on renewable energy in power distribution system has increased in recent years, with the main renewable sources being solar and wind. Due to the intermittent nature of renewable energy sources, such micro-generators produce time-varying energy which does not correspond at certain times of the day to the peak energy consumption of end users. For this reason, the use of energy storage units next to the grid contributes to the proper leveling of the buses’ voltage level according to Brazilian energy quality standards. In this work, the effect of the addition of a photovoltaic solar generator and a store of energy in the busbar voltages of an electric system is analyzed. The consumption profile is defined as the average hourly use of appliances in a common residence, and the generation profile is defined as a function of the solar irradiation available in a locality. The power summation method is validated with analytical calculation and is used to calculate the modules and angles of the voltages in the buses of an electrical system based on the IEEE standard, at each hour of the day and with defined load and generation profiles. The results show that bus 5 presents the worst voltage level at the power consumption peaks and stabilizes at the appropriate range with the inclusion of the energy storage during the night time period. Solar generator maintains improvement of the voltage level during the period when it receives solar irradiation, having peaks of production during the 12 pm (without exceeding the appropriate maximum levels of tension).
Abstract: In recent years, progress has been made in increasing the renewable energy share in the power sector particularly in the wind. The experimental study conducted in this paper aims to investigate the effects of number of blades and inflow wind speed on vibration signals of a vertical axis Savonius type wind turbine. The operation of the model of Savonius type wind turbine is conducted to compare two, three and four blades wind turbines to show vibration amplitudes related with wind speed. It is found that the increase of the number of blades leads to decrease of the vibration magnitude. Furthermore, inflow wind speed has reduced effect on the vibration level for higher number of blades.
Abstract: Wind energy is associated with many geographical factors including wind speed, climate change, surface topography, environmental impacts, and several economic factors, most notably the advancement of wind technology and energy prices. It is the fastest-growing and least economically expensive method for generating electricity. Wind energy generation is directly related to the characteristics of spatial wind. Therefore, the feasibility study for the wind energy conversion system is based on the value of the energy obtained relative to the initial investment and the cost of operation and maintenance. In Kuwait, wind energy is an appropriate choice as a source of energy generation. It can be used in groundwater extraction in agricultural areas such as Al-Abdali in the north and Al-Wafra in the south, or in fresh and brackish groundwater fields or remote and isolated locations such as border areas and projects away from conventional power electricity services, to take advantage of alternative energy, reduce pollutants, and reduce energy production costs. The study covers the State of Kuwait with an exception of metropolitan area. Climatic data were attained through the readings of eight distributed monitoring stations affiliated with Kuwait Institute for Scientific Research (KISR). The data were used to assess the daily, monthly, quarterly, and annual available wind energy accessible for utilization. The researchers applied the Suitability Model to analyze the study by using the ArcGIS program. It is a model of spatial analysis that compares more than one location based on grading weights to choose the most suitable one. The study criteria are: the average annual wind speed, land use, topography of land, distance from the main road networks, urban areas. According to the previous criteria, the four proposed locations to establish wind farm projects are selected based on the weights of the degree of suitability (excellent, good, average, and poor). The percentage of areas that represents the most suitable locations with an excellent rank (4) is 8% of Kuwait’s area. It is relatively distributed as follows: Al-Shqaya, Al-Dabdeba, Al-Salmi (5.22%), Al-Abdali (1.22%), Umm al-Hayman (0.70%), North Wafra and Al-Shaqeeq (0.86%). The study recommends to decision-makers to consider the proposed location (No.1), (Al-Shqaya, Al-Dabdaba, and Al-Salmi) as the most suitable location for future development of wind farms in Kuwait, this location is economically feasible.
Abstract: Steel tubular towers serving as support structures for large wind turbines are subjected to several hundred million stress cycles caused by the turbulent nature of the wind. This causes highcycle fatigue, which could govern the design of the tower. Maintaining the support structure after the wind turbines reach its typical 20-year design life has become a common practice; however, quantifying the changes in the reliability on the tower is not usual. In this paper the effect of fatigue damage in the wind turbine structure is studied whit the use of fracture mechanics, and a method to estimate the reliability over time of the structure is proposed. A representative wind turbine located in Oaxaca, Mexico is then studied. It is found that the system reliability is significantly affected by the accumulation of fatigue damage.
Abstract: This study focuses on the cooling of a photovoltaic
panel (PV). Indeed, the cooling improves the conversion capacity of
this one and maintains, under extreme conditions of air temperature,
the panel temperature at an appreciable level which avoids the
altering. To do this, a fan provides forced circulation of air. Because
the fan is supplied by the panel, it is necessary to determine the
optimum operating point that unites efficiency of the PV with the
consumption of the fan. For this matter, numerical simulations are
performed at varying mass flow rates of air, under two extreme air
temperatures (50°C, 25°C) and a fixed solar radiation (1000W.m2) in
a case of no wind.
Abstract: A Jet-stream airsail concept takes advantage of aerology
in order to fly without propulsion. Weather phenomena, especially jet
streams, are relatively permanent high winds blowing from west to
east, located at average altitudes and latitudes in both hemispheres.
To continuously extract energy from the jet-stream, the system is
composed of a propelled plane and a wind turbine interconnected by
a cable. This work presents the aerodynamic characteristics and the
behavior of the cable that links the two subsystems and transmits
energy from the turbine to the aircraft. Two ways of solving this
problem are explored: numerically and analytically. After obtaining
the optimal shape of the cross-section of the cable, its behavior
is analyzed as a 2D problem solved numerically and analytically.
Finally, a 3D extension could be considered by adding lateral forces.
The results of this work can be further used in the design process of
the overall system: aircraft-turbine.
Abstract: When a building is located in an urban area, it is
exposed to a wind of different characteristics then wind over an open
terrain. This is development of turbulent wake region behind an
upstream building. The interaction with upstream building can
produce significant changes in the response of the tall building. Here,
in this paper, an attempt has been made to study wind induced
interference effects on tall building. In order to study wind induced
interference effect (IF) on Tall Building, initially a tall building
(which is termed as Principal Building now on wards) with square
plan shape has been considered with different Height to Width Ratio
and total drag force is obtained considering different terrain
conditions as well as different incident wind direction. Then total
drag force on Principal Building is obtained by considering adjacent
building which is termed as Interfering Building now on wards with
different terrain conditions and incident wind angle. To execute
study, Computational Fluid Dynamics (CFD) Code namely Fluent
and Gambit have been used.
Abstract: Higher capacities of power plants together with
increased awareness on environmental considerations have led to
taller height of stacks. It is seen that strong wind can result in falling
of stacks. So, aerodynamic consideration of stacks is very important
in order to save the falling of stacks. One stack is not enough in
industries and power sectors and two or three stacks are required for
proper operation of the unit. It is very important to arrange the stacks
in proper way to resist their downfall. The present experimental
study concentrates on the mutual effect of three nearby stacks on
each other at three different arrangements, viz. linear, side-by-side
and triangular. The experiments find out the directions of resultant
forces acting on the stacks in different configurations so that proper
arrangement of supports can be made with respect to the wind
directionality obtained from local meteorological data. One can also
easily ascertain which stack is more vulnerable to wind in
comparison to the others for a particular configuration. Thus, this
study is important in studying the effect of wind force on three stacks
in different arrangements and is very helpful in placing the supports
in proper places in order to avoid failing of stack-like structures due
to wind.
Abstract: The construction of a civil structure inside a urban
area inevitably modifies the outdoor microclimate at the building
site. Wind speed, wind direction, air pollution, driving rain, radiation
and daylight are some of the main physical aspects that are subjected
to the major changes. The quantitative amount of these modifications
depends on the shape, size and orientation of the building and on its
interaction with the surrounding environment.The flow field over a
flat roof model building has been numerically investigated in order to
determine two-dimensional CFD guidelines for the calculation of the
turbulent flow over a structure immersed in an atmospheric boundary
layer. To this purpose, a complete validation campaign has been
performed through a systematic comparison of numerical simulations
with wind tunnel experimental data.Several turbulence models and
spatial node distributions have been tested for five different vertical
positions, respectively from the upstream leading edge to the
downstream bottom edge of the analyzed model. Flow field
characteristics in the neighborhood of the building model have been
numerically investigated, allowing a quantification of the capabilities
of the CFD code to predict the flow separation and the extension of
the recirculation regions.The proposed calculations have allowed the
development of a preliminary procedure to be used as a guidance in
selecting the appropriate grid configuration and corresponding
turbulence model for the prediction of the flow field over a twodimensional
roof architecture dominated by flow separation.
Abstract: wind catchers have been served as a cooling system, used to provide acceptable ventilation by means of renewable energy of wind. In the present study, the city of Yazd in arid climate is selected as case study. From the architecture point of view, learning about wind catchers in this study is done by means of field surveys. Research method for selection of the case is based on random form, and analytical method. Wind catcher typology and knowledge of relationship governing the wind catcher's architecture were those measures that are taken for the first time. 53 wind catchers were analyzed. The typology of the wind-catchers is done by the physical analyzing, patterns and common concepts as incorporated in them. How the architecture of wind catcher can influence their operations by analyzing thermal behavior are the archetypes of selected wind catchers. Calculating fluids dynamics science, fluent software and numerical analysis are used in this study as the most accurate analytical approach. The results obtained from these analyses show the formal specifications of wind catchers with optimum operation in Yazd. The knowledge obtained from the optimum model could be used for design and construction of wind catchers with more improved operation
Abstract: The connection between solar activity and adverse phenomena in the Earth’s environment that can affect space and ground based technologies has spurred interest in Space Weather (SW) research. A great effort has been put on the development of suitable models that can provide advanced forecast of SW events. With the progress in computational technology, it is becoming possible to develop operational large scale physics based models which can incorporate the most important physical processes and domains of the Sun-Earth system. In order to enhance our SW prediction capabilities we are developing advanced numerical tools. With operational requirements in mind, our goal is to develop a modular simulation framework of propagation of the disturbances from the Sun through interplanetary space to the Earth. Here, we report and discuss on the development of coronal field and solar wind components for a large scale MHD code. The model for these components is based on a potential field source surface model and an empirical Wang-Sheeley-Arge solar wind relation.
Abstract: A full six degrees of freedom (6-DOF) flight dynamics
model is proposed for the accurate prediction of short and long-range
trajectories of high spin and fin-stabilized projectiles via atmospheric
flight to final impact point. The projectiles is assumed to be both rigid
(non-flexible), and rotationally symmetric about its spin axis launched
at low and high pitch angles. The mathematical model is based on the
full equations of motion set up in the no-roll body reference frame and
is integrated numerically from given initial conditions at the firing
site. The projectiles maneuvering motion depends on the most
significant force and moment variations, in addition to wind and
gravity. The computational flight analysis takes into consideration the
Mach number and total angle of attack effects by means of the
variable aerodynamic coefficients. For the purposes of the present
work, linear interpolation has been applied from the tabulated database
of McCoy-s book. The developed computational method gives
satisfactory agreement with published data of verified experiments and
computational codes on atmospheric projectile trajectory analysis for
various initial firing flight conditions.
Abstract: METIS is the Multi Element Telescope for Imaging
and Spectroscopy, a Coronagraph aboard the European Space
Agency-s Solar Orbiter Mission aimed at the observation of the solar
corona via both VIS and UV/EUV narrow-band imaging and spectroscopy. METIS, with its multi-wavelength capabilities, will
study in detail the physical processes responsible for the corona heating and the origin and properties of the slow and fast solar wind.
METIS electronics will collect and process scientific data thanks to its detectors proximity electronics, the digital front-end subsystem
electronics and the MPPU, the Main Power and Processing Unit,
hosting a space-qualified processor, memories and some rad-hard
FPGAs acting as digital controllers.This paper reports on the overall
METIS electronics architecture and data processing capabilities
conceived to address all the scientific issues as a trade-off solution between requirements and allocated resources, just before the
Preliminary Design Review as an ESA milestone in April 2012.
Abstract: This paper compares planning results of the electricity and water generation inventory up to year 2030 in the State of
Kuwait. Currently, the generation inventory consists of oil and gas fired technologies only. The planning study considers two main cases. The first case, Reference case, examines a generation inventory based on oil and gas fired generation technologies only.
The second case examines the inclusion of renewables as part of the generation inventory under two scenarios. In the first scenario, Ref-RE, renewable build-out is based on optimum economic performance
of overall generation system. Result shows that the optimum installed
renewable capacity with electric energy generation of 11% . In the second scenario, Ref-RE20, the renewable capacity build-out is
forced to provide 20% of electric energy by 2030. The respective energy systems costs of Reference, Ref-RE and Ref-RE20 case
scenarios reach US dollar 24, 10 and 14 billion annually in 2030.
Abstract: Wind turbines with double output induction
generators can operate at variable speed permitting conversion
efficiency maximization over a wide range of wind velocities. This
paper presents the performance analysis of a wind driven double
output induction generator (DOIG) operating at varying shafts speed.
A periodic transient state analysis of DOIG equipped with two
converters is carried out using a hybrid induction machine model.
This paper simulates the harmonic content of waveforms in various
points of drive at different speeds, based on the hybrid model
(dqabc). Then the sinusoidal and trapezoidal pulse-width–modulation
control techniques are used in order to improve the power factor of
the machine and to weaken the injected low order harmonics to the
supply. Based on the frequency spectrum, total harmonics distortion,
distortion factor and power factor. Finally advantages of sinusoidal
and trapezoidal pulse width modulation techniques are compared.
Abstract: Over 90% of the world trade is carried by the
international shipping industry. As most of the countries are
developing, seaborne trade continues to expand to bring benefits for
consumers across the world. Studies show that world trade will
increase 70-80% through shipping in the next 15-20 years. Present
global fleet of 70000 commercial ships consumes approximately 200
million tonnes of diesel fuel a year and it is expected that it will be
around 350 million tonnes a year by 2020. It will increase the
demand for fuel and also increase the concentration of CO2 in the
atmosphere. So, it-s essential to control this massive fuel
consumption and CO2 emission. The idea is to utilize a diesel-wind
hybrid system for ship propulsion. Use of wind energy by installing
modern wing-sails in ships can drastically reduce the consumption of
diesel fuel. A huge amount of wind energy is available in oceans.
Whenever wind is available the wing-sails would be deployed and
the diesel engine would be throttled down and still the same forward
speed would be maintained. Wind direction in a particular shipping
route is not same throughout; it changes depending upon the global
wind pattern which depends on the latitude. So, the wing-sail
orientation should be such that it optimizes the use of wind energy.
We have made a computer programme in which by feeding the data
regarding wind velocity, wind direction, ship-motion direction; we
can find out the best wing-sail position and fuel saving for
commercial ships. We have calculated net fuel saving in certain
international shipping routes, for instance, from Mumbai in India to
Durban in South Africa. Our estimates show that about 8.3% diesel
fuel can be saved by utilizing the wind. We are also developing an
experimental model of the ship employing airfoils (small scale wingsail)
and going to test it in National Wind Tunnel Facility in IIT
Kanpur in order to develop a control mechanism for a system of
airfoils.