effect of wind

Abstract: The rapid increase of the urban population in developing countries such as India, has forced the re-evaluation of the importance of high rise buildings 8 . The impact of wind loads are to consider for the design of high rise building. There are many failures of structures have occurred in India due to wind. The wind loads on different types of structures are considered by IS 875 Part-3. The present study focuses on the effects of wind load on building with different aspect ratios i.e. H/B ratio, where H is the total height of the building frame and B is the base width of the building frame using STADD PRO. From this paper we get the Effect of wind load on height of building by varying the no. of stories with increasing in the Aspect Ratio. The analysis of multistory building for Class A and Class B zones for wind forces in terrain categories TC2 and TC3 is carried out. 3-D model is prepared for G+5 and G+11 multistory building in STAAD-Pro.

Abstract. This paper investigates the effect of wind flow direction on the fatigue loads on wind turbine within a wind farm, to determine the most critically loaded machines within the wind farm. The fatigue loads are calculated according IEC standards. In this study, the two layouts are considered. Additionally, this paper includes the effect of wind flow direction on the power efficiency of the wind farm for the two layouts. The simulations performed by StrathFarm, which is an in-house developed wind farm modeling tool, for the below and above rated wind speed flow with turbulence. In the regular and installed regular layouts at zeros degree of the prevailing wind flow direction, the spacing among turbines is eight diameters. At 90 degrees of wind flow direction the spacing between turbines is five diameters. The simulations demonstrate that the majority of the maximum fatigue loads occur at the range 40 and 70 degrees for the two layouts. However, there is small number of machines, which are experienced the highest fatigue loads at 90 degrees of wind flow direction. For the two layout the lowest power efficiency occurs at 10 degrees of wind flow direction. The regular layout is experienced same power efficiency at five and eight diameters spacing among turbine in the wind flow direction. The highest power efficiency occurs at wind flow angles, which produce the highest fatigue loads.

Hence, creep is collected at the 0 height. Each collector consisted of a rectangular entry opening, a central part and an air outlet. The collected sand was directed to a sampler with eight divisions for the eight wind direc- tions: north, northeast, east, southeast, south, EFFECT OF WIND DIRECTION ON AEOLIAN SAND TRANSPORT

In the present study, a detailed analysis has been made on the behaviour of the telecommunication tower subjected to wind and seismic loads with varying the bracing system of towers. Gust factor method is used for wind load analysis. Conducted analytical study on effect of wind on telecommunication towers, for wind speed of 50m/s for four combination of bracing systems; Also studied the effect of earthquake loading on telecommunication towers using Modal analysis and Response Spectrum method, for seismic zones III, IV and V for all the four combination of bracing systems.

foundations of our theories. The broadly accepted analysis of air speed and wind discussed in this paper has not only been used to support the current theories on optimal avian flight but also to form them. The validity of these and other one- dimensional studies in their current form may therefore also influence our theoretical foundations. Hence, a reanalysis of previous one-dimensional studies dealing with the effect of wind on air speed is desirable. The adaptive behavior of birds towards their environment, particularly wind, has important implications when incorporated into models of, for example, stopover strategies and take-off decisions during migration (Liechti and Bruderer, 1998; Weber et al., 1998; Weber and Hedenström, 2000) estimations of potential flight range of long distance migrants (Battley and Piersma, 2005), of optimal flight speeds of birds (Hedenström and Alerstam, 1995), energetic requirements during for migration (Butler et al., 1997) consequences for individual fitness (Clark and Butler, 1999) and the evolution of migratory strategies (Erni et al., 2005). In order to properly interpret model results or compare models to measurements we must ensure that the analysis underlying model assumptions or the predictions themselves is appropriate.

The major problem for the whole world is the availability of pure, clean and healthy water especially in rural areas. Desalination systems with the help of solar energy have been used in many countries to produce fresh water. The working of ion units has been classified into active and passive modes of operation. It is reported that the overall thermal efficiency of a passive distiller is higher than that an active distiller due to the lower operating temperature range researchers have observed the effects of climatic, and design parameters on the performance of single, effect active and passive solar stills (Kumar Suneja and Tiwari, 1999; Mink et al., 1998). It has been summarized that the productivity of the solar stills increases with the increase of solar radiation and ambient et al., 1971). But, here are contradictory results about the effect of wind velocity on solar still productivity.

Abstract: The rapid increase of the urban population in developing countries such as India, has forced the re-evaluation of the importance of high rise buildings 8 . The impact of wind loads are to consider for the design of high rise building. There are many failures of structures have occurred in India due to wind. The wind loads on different types of structures are considered by IS 875 Part-3. The present study focuses on the effects of wind load on building with different aspect ratios i.e. H/B ratio, where H is the total height of the building frame and B is the base width of the building frame using STADD PRO. From this paper we get the review on the Effect of wind load on height of building by varying the no. of stories with increasing in the Aspect Ratio.Keywords:High- rise building, Wind effects, Aspect ratio, STADD PRO-V8i

The along-wind loading or response of a building due to buffeting by wind can be assumed to consist of a mean component due to the action of the mean wind speed (eg, the mean-hourly wind speed) and a fluctuating component due to wind speed variations from the mean. The fluctuating wind is a random mixture of gusts or eddies of various sizes with the larger eddies occurring less often (i.e. with a lower average frequency) than for the smaller eddies. The natural frequency of vibration of most structures is sufficiently higher than the component of the fluctuating load effect imposed by the larger eddies. i.e. the average frequency with which large gusts occur is usually much less than any of the structure's natural frequencies of vibration and so they do not force the structure to respond dynamically. The loading due to those larger gusts (which are sometimes referred to as "background turbulence") can therefore be treated in a similar way as that due to the mean wind. The smaller eddies, however, because they occur more often, may induce the structure to vibrate at or near one (or more) of the structure's natural frequencies of vibration. This in turn induces a magnified dynamic load effect in the structure which can be significant. The separation of wind loading into mean and fluctuating components is the basis of the so-called "gust-factor" approach, which is treated in many design codes. The mean load component is evaluated from the mean wind speed using pressure and load coefficients. The fluctuating loads are determined separately by a method which makes an allowance for the intensity of turbulence at the site, size reduction effects, and dynamic amplification (Davenport, 1967). The dynamic response of buildings in the alongwind direction can be predicted with reasonable accuracy by the gust factor approach, provided the wind flow is not significantly affected by the presence of neighbouring tall buildings or surrounding terrain.

Abstract. Proper wind turbine design relies on the ability to accurately predict ultimate and fatigue loads of turbines. The load analysis process requires precise knowledge of the expected wind-inflow conditions as well as turbine structural and aerodynamic properties. However, uncertainty in most parameters is inevitable. It is therefore important to understand the impact such uncertainties have on the resulting loads. The goal of this work is to assess which input parameters have the greatest influence on turbine power, fatigue loads, and ulti- mate loads during normal turbine operation. An elementary effects sensitivity analysis is performed to identify the most sensitive parameters. Separate case studies are performed on (1) wind-inflow conditions and (2) turbine structural and aerodynamic properties, both cases using the National Renewable Energy Laboratory 5 MW base- line wind turbine. The Veers model was used to generate synthetic International Electrotechnical Commission (IEC) Kaimal turbulence spectrum inflow. The focus is on individual parameter sensitivity, though interactions between parameters are considered.

Early works regarding the correlation between the wind speed and load have been published in 1980s. The effects of the correlation between the load and wind have been indicated in [6] and [7]. In [7], the authors have addressed the dependency between the wind and load in an Irish case study. Load and wind correlation coefficient for this study was reported about 0.15 - 0.20, which was ignored to avoid the computational complexity. Seasonal correlation between the load and wind has been pointed out in [8]. In a study for the U.S. Department of Energy, it has been emphasized that these correlations “do exist” and have a complex pattern [9]. In [10], the authors claim a negative correlation between load and wind “in most systems.” Such dependency can affect system analysis and should be accurately represented. In [11], a method has been presented for modeling the correlation between the wind speed, solar insolation and load curves. This study has concluded that such a correlation, as an important factor, must be considered in the reliability evaluations.

Wind energy as a clean, widely distributed and environment friendly gas produces no emission and uses less space during operation. For planning a successful wind turbine one must familiar with the required location for installing wind turbine generator for adding a new source of property value in rural areas that have a hard time attracting new industry. With increase in efficiency of a wind turbine, more power can be generated and thus decreasing the need for expensive power generators that cause pollution. With this cost of power for the common people can be reduced. Wind velocity has great importance in increasing the power. In other word wind velocity have direct effect on efficiency

Wind is a phenomenon of great complexity because of the many flow situations arising from the interaction of wind with structures. Wind is composed of a multitude of eddies of varying sizes and rotational characteristics carried along in a general stream of air moving relative to the earth’s surface. The emergence of modern materials & construction techniques resulted in structures that are often to a degree unknown in the past, remarkably low in damping,& light in weight .Generally such structures are more affected by the action of wind. The structural should ensure that the structure should be safe & serviceable during its anticipated life even if it is subjected to wind loads. Wind forms the predominant source of loads in tall free standing structures .The effect of wind on tall structure can be divided into two components they are • Along wind effect

pressure exerted on the portal. It is important that the mechanical ventilation provides air velocity in the tunnel that is greater than the fire’s critical velocity, which ranges from 1.5 m/s for fires up to 10 MW, and up to 4 m/s for fires over 100 MW. This article establishes the importance of taking into account the gustiness of winds when determining the adequate safety of road tunnels. As a case study, research of the Kastelec tunnel was carried out, in an area where the gusty wind of the Bora blows. Research has shown that the effect of gusty wind, such as the example of the Bora wind, on the speed in a tunnel differs from that of a constant wind. It is necessary to consider a gust’s intensity, duration, and period of repetition. The velocity at the tunnel portal during the gust fluctuated depending on its curve. This effect also transfers to the movement of air in the tunnel. As the occurrence of the maximum speed of the gust is only short-term, followed by a period of low velocity wind, the mechanical ventilation air flow inertia prevents a greater drop in speed in the tunnel. By comparing the effect of constant wind, a significant difference between the wind velocities at which the tunnel air flow velocity is still adequate is determined. In all wind scenarios where the gusts were at 30 m/s, the ventilation velocity in the tunnel was adequate for the determined 10 MW fire and provided the extraction of smoke from the tunnel. Theoretical CFD models of the effect of wind have been validated with real wind measurements in the area of the Kastelec tunnel [23] and measurements from the tunnel tube [26]. Verification indicated up to a 5 % deviation in the results. On the basis of this, designed CFD models can be categorised as a good approximation of reality.

Fig. 8 shows the comparison between the first stage of the sun gear’s bending fatigue damage caused by NTM and ETM wind model with the mean wind speed ranges from 5 m/s to 20 m/s and turbulence intensity ranges from 12 % to 16 %. It can be observed that the damages caused by these two wind models are almost the same. Based on this conclusion, we can know that it is reasonable to only use the NTM wind model to study the effect of wind loads on gearbox’s fatigue life. This phenomenon may be caused by the wind turbine’s pitch control, since when the speed is beyond rated, the pitch angle is controlled so that constant input torque is acquired.

Earthen heritage constitutes 10% of sites on the World Heritage List and many of these sites are experiencing exten- sive deterioration caused by environmental forces, such as wind and rain. This study used a well-established test wall to investigate the impact of environmental conditions on the deterioration of earthen heritage at the remote and under-studied site of Suoyang Ancient City, Gansu Province, China, which is exhibiting widespread deteriora- tion. Test walls have previously been used in earthen heritage research as they allow controlled experiments to be undertaken on complex, realistic structures without risking damage or loss of value to the historic material. This study used portable wind and rain erosion simulation devices to investigate experimentally (i) the comparative effect of wind, sediment-laden wind and wind-driven rain in causing deterioration to earthen heritage and (ii) how the incipient deterioration features produced by wind, sediment-laden wind and wind-driven rain on the test wall relate to the deterioration features recorded on the historic city walls. The test wall was subjected to low, medium and high intensities of clean wind, sediment-laden wind and wind-driven rain. The extent of deterioration produced was measured using repeat, high resolution laser scans before and after each test run. The deterioration features caused by each environmental force were notably different with clean wind removing the loose surface material, sediment- laden wind causing pitting and wind-driven rain causing incipient gullying. These incipient features compare well with more developed features seen on the historic walls. Wind-driven rain caused the greatest amount of deteriora- tion while clean wind caused the least. However, as the frequency and duration of wind events at Suoyang is much greater than those of rain events, wind is likely to play an important role in the deterioration of earthen heritage over annual timescales. These findings show that conservation strategies at rammed earth sites like Suoyang need to address the impact of multiple environmental forces, such as clean wind, sediment laden wind and wind-driven rain. Keywords: Earthen heritage, Deterioration, Field experiment, Northwest China

II.INTERMITTENCY OF RENEWABLE ENERGY AND ITS IMPACT ON THE GRID MANAGER The intermittence of renewable energy is still considered a weak link in an energy production system based on wind, which generates power only when the wind blows. This locally varied wind can be nil, too low or too high and in this case the wind turbines cannot produce electricity (cut in and cut out wind speed). However, these local effects may be partly mitigated given the various climate environment of Moroccan regions, wind generation is not null at the same time. It is "Smoothing effect” of wind power, which is defined as the ability of a climate zone to smoothen or to offset the wind power generation of another area. According to this effect, the intermittent wind generation in a given region would be mostly offset by another region which itself would vary more or less in reverse giving the sum of productions more regular behaviour [6,7].

The Czech standard specifi cation ČSN 75 0255 (Calculation of wave eff ects on waterworks) deals with the estimation of overwater wind speed diff erently. The standard specifi cation introduce the another term for fetch – eff ective length of wind run over water. This approach has been used for the determination of wave characteristics on valley dams in the Czech Republic and Slovakia (Kratochvil, 1970; Lukáč, 1980; Šlezingr, 2004, 2007, 2010). Fig. 2 shows the relationship between the fetch length and k-factor which is applied in the equation for estimation of overwater velocity (ČSN 75 0255):

Gambit was used to create the fluid domain. The domain consist of three zones. The first zone is the Macro climate, or external air, zone 2 is the wind tower, and zone three is the micro climate or ventilated space. The macroclimate represents the external air supply or velocity inlet and also the exhaust from the wind tower or pressure outlet. The limits of the macroclimate for the fluid domain are dependant on the dimensions of the area of the wind tower, to avoid reversed flow or distortion of results the limits were set at 2.5 times the distance of each wall of the wind tower. Additionally the walls of the macro climate were set as symmetry, thus removing any adverse effect from the building geometry.

A 1/3 scaled model of a sun-tracking PV modules [14] were tested by Velicu et al. [15] in an open circuit wind tunnel. The drag and lift forces on the PV modules were measured using force transducers. The results showed that the force coefficients on the PV panel increased as the panel tilt angle increased from 0 o to 90 o .The force coefficients also increased as the wind velocity increased. Chung et al. [16] conducted wind tunnel tests to investigate the uplift on flat-plate PV collectors used for water heating. The PV modules were inclined at an angle of 25 o . The pressure measurements were taken along the centerline of the panel surfaces. A guide plate was attached to the test model of the PV collector to reduce the wind uplift. The effectiveness of this guide plate was investigated by varying its angular orientation at wind velocities ranging from 20m/s to 50m/s. The results showed that the differential pressures coefficients ∆ were highest at the front, lower edge of the panels, similar to observations by Shademan [17]. The ∆ reduced downstream of the panel and steadily rise towards the rear edge. The heights of the panel from the ground were varied during the tests. The result showed that the differential pressure coefficient, ∆ close to the rear edge increased with the height, thereby reducing the wind uplift. The least wind uplift was measured when the guide plate was installed at an angle of 90 o to the wind direction at the rear of the PV collector.

Automated microphone wind noise detection has been shown to considerably improve the ratings. This is because, provided that the microphone wind noise level fluctuates more quickly than the AM metrics, there are periods where the metrics will be reliable. Simulations indicate that detection of these periods has been successful, but further experiments are needed to confirm this in realistic scenarios. In the meantime the use of an automatic weather station with a sufficiently high time resolution might be the only way to inspire some confidence in the proposed AM ratings. The wind noise detector is available as an open source Cþþ program (Kendrick et al., 2014).