Effect Of Wind Pressure Research Articles

Finite Element Analysis on Negative Wind Pressure Stress of External Wall Insulation Layer

With excellent flame retardation and thermal insulation properties, SY self-temperature regulation and phase change energy-saving wall insulation material (the material) is composed of concrete and volcano perlite. At present, applied research of this material is not very thorough,especially under the condition of temperature variation, seasonal wind change in North China. In this paper, finite element analysis of external wall insulation layer of the Experimental Teaching Building in Taiyuan University of Science and Technology under negative wind pressure effect is performed. The negative wind load calculated is applied to the surface of the thermal insulation layer as uniform load, and the results show that the material used in the building which shorter than 80 meters in the Taiyuan area has no shedding or destruction under the negative air pressure. This material is safe and available.

Large fog collectors: New strategies for collection efficiency and structural response to wind pressure

Most studies of large fog collectors (LFC) have focused on the collection efficiency, the amount of water collected, or economic and social aspects, but have not addressed the effects of strong winds on the system. Wind pressure is directly related to fog water collection efficiency but on the other hand may cause serious damage on the structure of LFCs. This study focuses in the effects of wind pressure on the components of the LFC as an integral system, and the ways to face strong winds with no significant damage. For this purpose we analysed cases of mechanical failure of LFCs both in our experimental station at Peña Blanca in Chile and elsewhere.The effects of wind pressure can be described as a sequence of physical processes, starting with the mesh deformation as a way of adapting to the induced stresses. For a big enough pressure, local stress concentrations generate a progressive rupture of the mesh. In cases where the mesh is sufficiently strong the wind force causes the partial or total collapse of the structure.Usually the weakest part is the mesh, especially close to where it is attached to the structure. The way the mesh is attached to the frame or cable of the structure is particularly important since it can induce significant stress concentrations.Mesh failure before the structure failure may be considered as a mechanical fuse, since it is cheaper to repair. However, more practical mechanical fuses can be conceived.In relation to structural performance and water collection efficiency, we propose a new design strategy that considers a three-dimensional spatial display of the collection screen, oblique incidence angle of wind on mesh and small mesh area between the supporting frame. The proposed design strategies consider both the wind pressure on mesh and structure and the collection efficiency as an integral solution for the LFC. These new design strategies are the final output of this research. Applying these strategies a multi-funnel LFC is proposed, which is far more efficient than the conventional one, and even though it is more expensive, the final cost of the collected water should be notoriously reduced.

The Effects of Wind Pressure on Mass Burning Rates of Alcohol Pool Fires in an Inclined Wind Tunnel

In order to study the effects of different wind direction on combustion characteristics of alcohol pool fires, an inclinable wind tunnel was developed for providing venting wind with different directions. The control parameters of the experiments include the tunnel wind velocity, which can be altered from 0 to 3.0 ms –1 , and the tunnel inclination angle, which can be sloped from 0°to 30°while the fuel pan keeping horizontal inside the tunnel. The results show that the mass burning rate increases faster with increasing the slope angle of the wind tunnel when the wind speed is less than 1.5 ms –1 .I n addition, a relationship between the mass burning rate of the pool fire and the wind direction has been determined, that agrees well with the experimental results.

Analysis and Evaluation of Manoeuvrability Characteristics of Polish Ferries m/f „Polonia” and m/f „Gryf”

The paper describes some specific manner of M/F Polonia manoeuvring at the Ystad harbour where she is regarded to be over maximal ship and also M/F Gryf manoeuvring at Trelleborg, taking into consideration the effect of wind pressure into the ship's superstructures and houses.

Solar wind pressure effects on Jupiter decametric radio emissions independent of Io

This paper investigates the effects of the solar wind dynamic pressure on Jupiter auroral radio emissions at decametric wavelengths that are not controlled by the electrodynamic interaction with the moon Io (non-Io DAM). In order to conduct this study, Nançay decametric array radio data are analyzed for the 1996–1999 period. Solar wind conditions at Jupiter's orbit are studied using the Michigan University solar wind propagation model (mSWiM). Interplanetary fast shocks (forward shocks, FS, or reverse shocks, RS), and average solar wind dynamic pressure are correlated with non-Io DAM emission occurrence, duration and power. It is found that non-Io DAM emissions occur preferentially during periods of enhanced solar wind dynamic pressure and after a FS or a RS arrival at Jupiter. The dawn (non-Io B-type) and dusk (non-Io-A-type) radio emissions are investigated separately and show (1) a dawn-dusk asymmetry consistent with prior studies and auroral ultraviolet (UV) observations, and (2) different behaviors in response to solar wind shocks. Our study confirms the solar wind control of – at least a part of – the non-Io DAM, and refines the scenario of response of the radio emissions to the solar wind interaction with the Jovian magnetosphere.

수치해석을 이용한 초고층 주거건물에서 외풍영향에 의한 외벽 압력 분포 분석

ABSTRACT:The object of this study is to analyze and evaluate outdoor wind pressure effect in a high-rise residential building when seasonal wind blow on coast area. The target building consists of 3 tower buildings over 250m in height. For the evaluation of the outdoor wind effect, CFD simulation was performed. The results of the simulations are as follows：1) In that case of high-rise building, horizontal stream is more affected than vertical stream. 2) In case of summer season northeasterly wind, building pressure distributions are unstable and surface pressures of outside are effected respectively. 3) In case of winter season westerly wind, building preassure differentiations are not so much because of screening effects of the B, and the C buildings. 4) In case of winter season northwesterly wind, front wind affects on the A building directly because of no obstacles.Keywords:High-rise building(초고층 건물), Stack effect(굴뚝효과), Outdoor wind effect(외풍 영향), Airflow analysis(공기유동 분석) †Corresponding author Tel.: +82-51-510-2492; fax: +82-51-514-2230 E-mail address: ycahn@pusan.ac.kr

English

    A multiple-skin facade is an envelope construction that consists of two transparent surfaces separated by a cavity. The extra skin can reduce both cooling demand in summer and heating demand in winter. Solar radiation entering through the outer skin on the south face of the building will heat the air in the cavity. Depending on whether there is a demand for heating or cooling, this preheated air can either be drawn into the interior spaces or ventilated out of the building.These kinds of systems can be varied, depending on the arrangement of the air cavity section. Some examples of variations are the shaft-box window, the corridor facade, the multi-storey double-skin facade, and the box-window facade. The advantages of the double-skin facade are that it provides acoustic insulation, thermal insulation, and reduction of the effects of wind pressure; this approach allows natural or fan-supported ventilation and the possibility of rehabilitating existing single-skin facades by the addition of a second skin. The disadvantages of the system are its higher cost, the lack of practical information on fire protection, reduction of available space for offices, and less room-to-room or floor-to-floor sound insulation. In this study, the authors chose to conduct a parametric study for warm climates to provide a design aid for architects and designers. The parameters studied were the width of the cavity between the double skins, the area of the openings, the height of the buildings, the height of the transparent chimney added to the top of the south double facade, and the arrangements of open and closed openings. The effects of these parameters on airflow within the building and levels of thermal comfort were studied.   Key words: TAS software, double-skin facade, natural ventilation, warm-climate building problems. &nbsp

Behavior of precast, prestressed concrete sandwich wall panels reinforced with CFRP shear grid

This paper describes the structural behavior of precast, prestressed concrete sandwich wall panels reinforced with carbon-fiber-reinforced polymer (CFRP) shear grid to achieve composite action. Use of CFRP as a shear transfer mechanism was intended to increase the thermal insulation efficiency, enhance the service life, and increase the overall structural capacities of the panels. This study included testing of six full-scale sandwich wall panels, each measuring 20 ft x 12 ft (6.1 m x 3.7 m). The panels consisted of two outer prestressed concrete wythes and an inner insulation wythe. The study included two types of insulation and several shear transfer mechanisms with different CFRP reinforcement ratios to examine the degree of composite action developed between the two concrete wythes. All panels were simultaneously subjected to applied gravity and lateral loads. Reverse-cyclic lateral loads simulated the effects of wind pressure and suction. All panels were subjected to approximately 4000 cycles of lateral loading with the presence of factored gravity load. Following each fatigue regime, the lateral loads were increased until failure was achieved. Test results of the experimental program were compared with theoretical predictions of fully composite and noncomposite actions to evaluate the percent composite action and to assess the optimum panel configuration.

Radioactive 85Kr and CO2 Balance for Ventilation Rate Measurements and Gaseous Emissions Quantification through Naturally Ventilated Barns

Animal housing is a major source of gaseous emissions, such as ammonia (NH3), methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). Ammonia is an atmospheric pollutant and responsible for eutrophication and soil acidification, while CO2, CH4, and N2O are greenhouse gases (GHG) that contribute to global warming. The quantification of gaseous emissions from livestock buildings with natural ventilation systems is a particularly difficult task and is associated with uncertainties that are largely unknown. One key issue is to measure the ventilation rate and then to quantify the gaseous emissions. Therefore, in this study, the ventilation rate was determined by three different methods simultaneously. Field experiments were carried out to study the ventilation rate in a naturally ventilated dairy barn located in northern Germany during the summer seasons from 2006 to 2010. The air exchange rates (AER) as well as the ventilation rates were determined by the decay of the radioactive tracer krypton-85, the carbon dioxide (CO2) balance, which was used as the reference method in this study, and the combined effects of wind pressure and temperature difference forces (WT method). Subsequently, the results were compared with each other by carrying out Pearson correlation analysis and developing a regression model. During each field experiment, continuous measurements of gas concentrations (NH3, CO2, CH4, and N2O) inside and outside the building and 85Kr tracer gas experiments were carried out. Meanwhile, the temperature was measured and recorded inside and outside the barn. Furthermore, the wind velocity was measured. Although the WT method showed minor overestimation by about 1.11 (p < 0.05) times the reference method, it is not reliable because it showed no linear correlation (0.05; p = 0.88) with the reference method. This was due to large fluctuations in the wind velocity (direction and speed), which negatively affected the WT method, which is basically dependent on wind velocity. In contrast, the 85Kr tracer gas technique showed a good linear correlation (0.82; p < 0.05) with the reference method, which accentuates that the 85Kr tracer gas technique is a promising method. However, this technique overestimated the air exchange rate by about 2.05 (p < 0.05) times the reference method. Therefore, the 85Kr tracer gas technique should be further developed to produce values consistent with those estimated by the reference method. The emissions factors, subject to the reference method, were 32, 157.7, 13736, and 7.9 kg year-1 AU-1 for NH3, CH4, CO2, and N2O, respectively.

Structural Performance of Sandwich Wall Panels with Different Foam Core Densities in One-way Bending

The flexural behavior of a new sandwich panel proposed for cladding of buildings is studied. The panel is fabricated by laminating two glass fiber-reinforced polymer skins to a prefabricated polyurethane foam core. Two different densities for the core are explored, namely; a 0.31 kN/m3, referred to herein as ‘soft’ foam, and a 0.63 kN/m3, referred to as ‘hard’ foam. Ten 1500 × 300 × 76 mm3 panels were tested in flexure. For each core density, three similar panels were tested to establish the reproducibility of test results as a measure of quality control of fabrication. The panels were tested in three-point and four-point bending as well as under uniform load. The effect of wind pressure and suction was simulated for some panels by applying cyclic bending. It was shown that flexural strength and stiffness increased substantially, by 165% and 113%, respectively, as the core density was doubled. The contributions of shear deformation of the soft and hard cores to mid-span deflection were 75% and 50%, respectively. Panels with soft cores were vulnerable to localized effects under concentrated loads, and suffered inwards wrinkling of the compression skin at a lower ultimate strength. Low cycle fatigue resulted in some residual deflection upon unloading but insignificant stiffness degradation.

Effect of Wind Pressure on Horizontal Alignment of Highways

The geometric design of highway alignment consists mainly of the design of horizontal alignment and Vertical alignment. The more important step in horizontal alignment design is the curve radius determination. The equation used for horizontal curve radius determination is developed with assumption that when vehicle run on curved section, there are an acting force on it. This force include the centrifugal force that try to push vehicle out off its path , on the other hand there are resisting forces try to keep the vehicle on its path. Those include the friction between road surface and tires and forces resulting from sloping the highway cross section. When a vehicle on rural highway with high embankment the wind Pressure will play an important role in force system acting on vehicle because of increasing in wind pressure intensity at these conditions (rural highway, i.e open areas, high embankment). The purpose of this paper is to present a new equation for horizontal curve radius determination taking in to account the wind force effect in addition to other forces acting on vehicle The resulting equation relates vehicle length, height and weight and the wind pressure as well as the other factors in traditional equation. Effect of each parameter on design radius was investigated for the case where the wind direction is acted with the same centrifugal force direction. It has been found that the required minimum radius increase with the decreasing of vehicle weight or in the other words the vehicle permitted speed decrease with the decreasing of vehicle weight. On the other hand, the required curve radius increases with vehicle height increasing. Consequently, permitted height of bags loaded on a truck is related to the type of loads. Derived equation can also be used for estimation of the permitted truck speed on existing roads especially in case of bad weathers The comparison between the traditional and suggested equation showed that maximum difference is about 160 % which results at high wind pressure while the difference is up to 20 % for low wind pressure

Wind Pressure and Strain Measurements on Bridges. II: Strain Transducer Development

The University of Colorado at Denver has been studying the effect of wind pressure on historic bridges to determine the structural adequacy of these structures. Several historic bridges have been field instrumented and tested to determine the member forces due to actual lateral wind pressures. This paper focuses on the development of an inexpensive reusable strain transducer that can be conveniently and nondestructively clamped to any structural member in a field condition. Prototype strain transducers have been extensively tested in the laboratory to verify reliability and repeatability of results and have been compared to finite-element modeling results. The best strain transducer has been successfully used in the field on the historic truss bridges. Each strain transducer costs approximately $50.

Wind Pressure and Strain Measurements on Bridges. I: Instrumentation/Data Collection System

The University of Colorado at Denver has been studying the effect of wind pressure on historic bridges to determine the structural adequacy of these structures. A number of historic bridges have been field instrumented and tested to determine the member forces due to actual lateral wind pressures. This paper focuses on the instrumentation/data collection system developed for the project and field data collection for one bridge. The instrumentation/data collection system needed to be low cost due to the project budget and needed to obtain measurements at a sampling rate sufficiently rapid to capture short-duration wind gusts.

Thermodynamic analysis of wind energy

Wind energy is assessed thermodynamically, from resource and technology perspectives. The thermodynamic characteristics of wind are considered. Wind speed is affected by air temperature and pressure and has an effect on wind turbine performance, based on wind chill effect and Bernoulli's equation. The wind chill effect leads to temperature differences that suggest enthalpy and entropy components must be considered in a thermodynamic analysis. The wind pressure effect based on Bernoulli's equation affects the entropy of wind. These components have not previously been considered in evaluations of wind turbine efficiency for electricity generation. A new efficiency formula for wind energy systems is described, which provides important information about the system. It is seen that average differences between energy and exergy efficiencies are approximately 40% at low wind speeds and up to approximately 55% at high wind speeds. Copyright © 2005 John Wiley & Sons, Ltd.

Spiral Galaxy - ICM Interactions in the Virgo Cluster

We discuss HI and optical evidence for ongoing ICM-ISM interactions in 6 Hi-deficient Virgo cluster spiral galaxies. One of the clearest cases is the highly inclined Virgo galaxy NGC 4522, which has a normal stellar disk but a truncated gas disk, and lots of extraplanar gas right next to the gas truncation radius in the disk. Unusually strong HI, Hα and radio continuum emission are all detected from the extraplanar gas. The radio continuum polarized flux and spectral index peak on the side opposite the extraplanar gas, suggesting ongoing pressure by the ICM. Four other HI-deficient edge-on Virgo spirals show evidence of extraplanar ISM gas or exhibit asymmetries in their disk HI distributions, but contain much less extraplanar HI than NGC 4522. Comparison with recent simulations suggests this difference may be evolutionary, with large surface densities of extraplanar gas observed only in early phases of an ICM-ISM interaction. In NGC 4569, the Hα image shows 2 effects of ICM pressure on the galaxy ISM. An anomalous arm of HII regions, possibly extraplanar, emerges from the edge of a truncated Hα disk. This resembles the arms seen in simulations which are formed by the combined effects of wind pressure plus rotation. An extended nebulosity near the minor axis, also in the NW, is interpreted as a starburst outflow bubble disturbed by ICM wind pressure.

WIND STABILITY ANALYSIS OF URBAN TREES

We present an analysis of the stability of urban trees under the effect of wind pressure. The modeling is led using the yield design theory from a cinematic approach ('by the exterior'). The family of ruin mechanisms retained are very simple block rotation, as in-situ observations show. We develop entirely the mechanical modeling leading to the definition of an assistance tool for the preventive maintenance. Methods to evaluate the calculation parameters are presented. To make this evaluation the most objective, we derived it from data measured on the tree and approximations based on established results in the literature. This approach is then used to build the software 'CILVA' which is presented in another paper. Full Text (PDF format, 380000 bytes)

Buckling analysis of cooling tower shells subjected to non-axisymmetric wind pressures

Safety against buckling under wind loading is an important criterion in the design of cooling tower shells. A rigorous bifurcation analysis of a cooling tower shell subjected to actual non-axisymmetric wind pressure distribution using quadrilateral or triangular elements is time consuming. An attempt at such an analysis using ring elements in the form of a frustum of a cone with only four degrees of freedom per nodal line has yielded encouraging results. The coupling of harmonics that occurs in a bifurcation analysis using a Fourier series has been found to be only of minor disadvantage in the computational efforts. A computer program has been developed using this alternative method. No simplifying assumptions such as equivalent axisymmetric pressure or stress have been made for wind pressure effects. The results obtained from the present analysis are compared with the results available in the literature.

Studies on Wind Load and Swinging Motion of Overhead Transmission Line : 2nd Report, Practical Calculations and Scale Effects of Wind Pressure

Studies on Wind Load and Swinging Motion of Overhead Transmission Line : 2nd Report, Practical Calculations and Scale Effects of Wind Pressure

Fire-Fighting Air Foams (5) Effect of Wind Pressure on the Rate of Coverage of the Air Foams

Fire-Fighting Air Foams (5) Effect of Wind Pressure on the Rate of Coverage of the Air Foams

Note on the effect of wind pressure on the pitch of organ pipes

In books on acoustics the pitch of organ pipes is treated as being dependent solely on the length of the pipe, while at the same time it is recognised that, as a consequence of the conditions existing at the open end or ends, the length in question is somewhat greater than that of the pipe itself. The “correction for open ends” has been calculated for particular cases, and for the open end of a pipe of circular section amounts to an addition to its length of about 0·82 times the radius. The conditions at the base, or speaking end, are more complex, and for this (as far as I am aware) no similar correction has been worked out. For these reasons the natural pitch of an organ pipe cannot be accurately determined from its material dimensions, but only by experiment; such, for instance, as noting the frequency of an exterior source of sound which produces the maximum resonance in the pipe. When an organ pipe is made to “speak” in the ordinary way, it is a matter of common knowledge that the pitch of note produced is to some extent dependent on the pressure of the wind supply, and the fact (though often mentioned) has not been satisfactorily accounted for (Lord Rayleigh has published an accurate series of experiments on this subject, which will be referred to later.) The true explanation is exceedingly simple, but, like many other problems of the flow of fluids, it cannot, at present at any rate, be treated on a purely dynamical basis.