Protective benefit of folded linear HDPE board sand fences along the Golmud-Korla Railway,China:Field observation and wind tunnel study

The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction characteristics.This study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal protection.This study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand fences.The results suggest that the airflow around the fence creates clear zoning characteristics.The deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the BSF.At different wind speeds,the airflow at 2 and 5 h on the DSF is not disturbed.The WSP(wind speed profile)presents a logarithmic distribution.The airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic law.However,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic distribution.Meanwhile,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field tests.The overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test results.This study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.

Numerical Modeling and Technico-Economic Analysis of a Hybrid Energy Production System for Self-Consumption: Case of Rural Area in the Comoros

This study aims to provide electricity to a remote village in the Union of Comoros that has been affected by energy problems for over 40 years. The study uses a 50 kW diesel generator, a 10 kW wind turbine, 1500 kW photovoltaic solar panels, a converter, and storage batteries as the proposed sources. The main objective of this study is to conduct a detailed analysis and optimization of a hybrid diesel and renewable energy system to meet the electricity demand of a remote area village of 800 to 1500 inhabitants located in the north of Ngazidja Island in Comoros. The study uses the Hybrid Optimization Model for Electric Renewable (HOMER) Pro to conduct simulations and optimize the analysis using meteorological data from Comoros. The results show that hybrid combination is more profitable in terms of margin on economic cost with a less expensive investment. With a diesel cost of $1/L, an average wind speed of 5.09 m/s and a solar irradiation value of 6.14 kWh/m2/day, the system works well with a proportion of renewable energy production of 99.44% with an emission quantity of 1311.407 kg/year. 99.2% of the production comes from renewable sources with an estimated energy surplus of 2,125,344 kWh/year with the cost of electricity (COE) estimated at $0.18/kWh, presenting a cost-effective alternative compared to current market rates. These results present better optimization of the used hybrid energy system, satisfying energy demand and reducing the environmental impact.

NUMERICAL SIMULATION ON THE WIND FIELD STRUCTURE OF A MOUNTAINOUS AREA BESIDE SOUTH CHINA SEA DURING THE LANDFALL OF TYPHOON MOLAVE

Leveraging the commercial CFD software FLUENT,the fine-scale three-dimensional wind structure over the Paiya Mountains on the Dapeng Peninsula near Shenzhen,a city on the seashore of South China Sea,during the landfall of Typhoon Molave has been simulated and analyzed.Through the study,a conceptual wind structure model for mountainous areas under strong wind condition is established and the following conclusions are obtained as follows:(1)FLUENT can reasonably simulate a three-dimensional wind structure over mountainous areas under strong wind conditions;(2)the kinetic effect of a mountain can intensify wind speed in the windward side of the mountain and the area over the mountain peak;and(3)in the leeward side of the mountain,wind speed is relatively lower with relatively stronger wind shear and turbulence.

A Tangential Wind Profile for Simulating Strong Tropical Cyclones with MM5

A new tangential wind profile for simulating strong tropical cyclones is put forward and planted into the NCAR- AFWA tropical cyclone bogussing scheme in MM5. The scheme for the new profile can make full use of the information from routine typhoon reports, including not only the maximum wind, but also the additional information of the wind speeds of 25.7 and 15.4 ms-1 and their corresponding radii, which are usually provided for strong cyclones. Thus, the new profile can be used to describe the outer structure of cyclones more accurately than by using the earlier scheme of MM5 in which on- ly the maximum wind speed is considered. Numerical experimental forecasts of two strong tropical cyclones are performed to examine the new profile. Results show that by using the new profile the prediction of both cyclones’ intensity can be obvi- ously improved, but the effects on the track prediction of the two cyclones are different. It seems that the new profile might be more suitable for strong cyclones with shifted tracks. However, the conclusion is drawn from only two typhoon cases, so more cases are needed to evaluate the new profile.

On seismic strengthening area before strong and great shocks and its mechanism

By systematically studying seismic strengthening areas before 85 earthquakes with M>=6.0 in China, some results have been extracted. 1) Earthquake active strengthening area exists universally before strong shock or great earthquake; 2) The size of the strengthening area and its appearing time will increase when the earthquake magnitude increases; 3) The rate between the size of seismic strengthening area and the size of the source region decreases when earthquake magnitude increases; 4) The appearing time of the earthquake active strengthening region in the eastern part of China is longer than that in the western part of China. The above characteristics have been preliminarily explained qualitatively and half-quantitatively by applying the strong body earthquake generating model and the hard inclusion theory. Then applying the seismic strengthening area, we have obtained long-term predictions of 2 earthquakes, so the seismic strengthening area before strong earthquake or great earthquakes is a universal phenomenon, which has some mechanical base.

Seismic hazard analysis of Tianjin area based on strong ground motion prediction

Taking Tianjin as an example, this paper proposed a methodology and process for evaluating near-fault strong ground motions from future earthquakes to mitigate earthquake damage for the metropolitan area and important engineering structures. The result of strong ground motion was predicted for Tianjin main faults by the hybrid method which mainly con- sists of 3D finite difference method and stochastic Green＇s function. Simulation is performed for 3D structures of Tianjin re- gion and characterized asperity models. The characterized asperity model describing source heterogeneity is introduced fol- lowing the fault information from the project of Tianjin Active Faults and Seismic Hazard Assessment. We simulated the worst case that two earthquakes separately occur. The results indicate that the fault position, rupture process and the sedi- mentary deposits of the basin significantly affect amplification of the simulated ground motion. Our results also demonstrate the possibility of practical simulating wave propagation including basin induced surface waves in broad frequency-band, for seismic hazard analysis near the fault from future earthquakes in urbanized areas.

Evaluation of survival stow position and stability analysis for heliostat under strong wind

Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was established to calculate the wind load coefficients in various survival stow positions. In order to explore the best survival stow position for the heliostat under the strong wind, eigenvalue buckling analysis method was introduced to predict the critical wind load theoretically. Considering the impact of the nonlinearity and initial geometrical imperfection, the nonlinear post-buckling behaviors of the heliostat were investigated by load-displacement curves in the full equilibrium process. Eventually, combining B-R criterion with equivalent displacement principle the dynamic critical wind speed and load amplitude coefficient were evaluated. The results show that the determination for the best survival stow position is too hasty just by the wind load coefficients. The geometric nonlinearity has a great effect on the stability bearing capacity of the heliostat, while the effects of the material nonlinearity and initial geometrical imperfection are relatively small. And the heliostat is insensitive to the initial geometrical imperfection. In addition, the heliostat has the highest safety factor for wind-resistant performance in the stow position of 90-90 which can be taken as the best survival stow position. In this case, the extreme survival wind speeds for the static and dynamic stability are 150 m/s and 36 m/s, respectively.

Wind Tunnel Study of Multiple Factors Affecting Wind Erosion from Cropland in Agro-pastoral Area of Inner Mongolia,China

In this paper,the process of wind erosion on two kinds of soil from the agro-pastoral area of Inner Mongolia are studied using wind tunnel experiments,considering the wind speed,blown angle of wind and soil moisture content.The results showed that the modulus of soil wind erosion increases with an increase of wind speed.When the wind speed exceeds a critical value,the soil wind erosion suddenly increases.The critical speed for both kinds of soil is within the range of 7-8m·s-1.For a constant wind speed,the rate of soil wind erosion changes from increasing to falling at a critical soil slope.The critical slope of loam soil and sandy loam soil is 20° and 10°,respectively.Soil moisture content has a significant effect on wind erosion.Soil wind erosion of both soils decreases with an increase of the soil water content in two treatments,however,for treatment two,the increasing trends of wind erosion for two soils with the falling of soil water content are no significant,especially for the loam soil,and in the same soil water content,the wind erosion of two soils in treatment one is significantly higher than treatment two,this indicates reducing the disturbance of soil surface can evidently control the soil wind erosion.

Analysis of Special Strong Wind and Severe Rainstorm Caused by Typhoon Rammasun in Guangxi, China

Based on conventional meteorological observation data, NCEP 1° × 1° reanalysis data, reanalysis data with resolution 0.75° × 0.75° from ECMWF and Doppler weather radar, we analyzed the weather conditions and physical characteristics of Super Typhoon Rammasun (1409), which caused special strong wind and severe rainstorm in Guangxi. The results show that: 1) Typhoon Rammasun offshore sudden strengthening in one of the main reasons was that loop pressure ridge superimposed into the westward extension of subtropical high, to making enable rapid strengthening of the subtropical high, so the subtropical high advanced faster than the Rammasun move, Rammasun center of the subtropical high distance reduced and the gradient increased;2) Rammasun northward to south china coast with plenty of vapor following ITCZ, before landing, southwest monsoon and cross-equatorial flow were involved, Rammasun got latent heat of monsoon jet, enabling it to strengthen in offshore;3) Rammasun from the Qiongzhou Strait into the northern Gulf, therefore the Strait of short passages and both sides belong to the low zone, friction consumption smaller, that was the main reason what was able to maintain the strength of the super typhoon, when Rammasun into the Beibu Gulf;4) Diagnostic analysis shows that Rammasun before entering the northern Gulf and into the Beibu Gulf later, vorticity weakened, divergence and vapor flux divergence changed were smaller, meanwhile, vertical ascent speed and latent heat transport both increased, which was important reason of severe rainstorm caused by Rammasun.

Numerical Prediction of Strong Wind Induced by Topographic Effect

This paper describes the numerical study of nonstratified airflow over a real complex terrain. Attention is focused on the mechanism of a local strong wind induced by a topographic effect. In order to clarify the mechanism of the occurrence of strong winds accompanied by the effects of terrain, the use of a numerical simulation is very effective, in which conditions can be set without the influence of ground roughness and temperature distribution. As a result, airflow converged to a small basin of mountain terrain in the upper stream, and local strong wind was generated leeward along the slope of the mountain terrain. Furthermore, the influence of the reproduction accuracy of geographical features, that is, horizontal grid resolution, was examined. Consequently, to reproduce the above-mentioned local strong wind, it was shown that horizontal grid resolution from 50 m to about 100 m was necessary.

Determination method of load balance ranges for train operation safety under strong wind

The aerodynamic performances of a passenger car and a box car with different heights of windbreak walls under strong wind were studied using the numerical simulations, and the changes of aerodynamic side force, lift force and overturning moment with different wind speeds and wall heights were calculated. According to the principle of static moment balance of vehicles, the overturning coefficients of trains with different wind speeds and wall heights were obtained. Based on the influence of wind speed and wall height on the aerodynamic performance and the overturning stability of trains, a method of determination of the load balance ranges for the train operation safety was proposed, which made the overturning coefficient have nearly closed interval. A min(|A1|+|A2|), s.t. |A1|→|A2|(A1 refers to the downwind overturning coefficient and A2 refers to the upwind overturning coefficient)was found. This minimum value helps to lower the wall height as much as possible, and meanwhile, guarantees the operation safety of various types of trains under strong wind. This method has been used for the construction and improvement of the windbreak walls along the Lanzhou–Xinjiang railway(from Lanzhou to Urumqi, China).

Spatiotemporal change of beneficiary area from wind erosion prevention service in the Ulan Buh Desert in 2008 and 2018

The Ulan Buh Desert is one of the eight deserts in China that provides wind erosion prevention service(i.e.,the ecosystem;vegetation,production,and construction activities that promote sand fixation).It is significant for the construction of the national ecological barrier,and the protection of the ecological security in the Yellow River and North China.In this study,we selected two representative years(2008 and 2018)and quantified wind erosion prevention service from the Ulan Buh Desert using the RWEQ model.Meanwhile,the HYSPLIT model was used to simulate the spatial flow process from the service supply area to the beneficiary area and to determine its scope.The specific dust reduction amount in the beneficiary area was then calculated.The energy and the time-space relation of wind erosion prevention service in the areas that receive benefits from Ulan Buh Desert were compared before and after implementing environmental restoration measures.The results showed that:(1)the total amount of wind erosion prevention in the Ulan Buh Desert in 2018 was 2.12×10^(10)kg,which was 5.17 times higher than that in 2008;(2)in 2018,the distribution density of the flow path of wind erosion prevention service was lower than that in 2008,and the flow paths in each year were concentrated in the beneficiary areas with the path distribution frequency of less than 10%;(3)the total dust reduction in the downwind area of the Ulan Buh Desert in 2018 was higher than that in 2008,totaling 15.54 million tons.Inner Mongolia Autonomous Region and Shanxi Province had the most significant amount of dust reduction.

Study of the Seismicity of Strong Earthquakes in the Yunnan Area

Yunnan is located in the east margin of the collision zone between the India Plate and the Eurasian Plate on the Chinese Continent, where crustal movement is violent and moderatestrong earthquakes are frequent. In addition, the area features marked active block movement. Therefore, Yunnan is a perfect place for research on strong earthquake activity. Through the study on the temporal and spatial distribution of the M ≥ 6.7 earthquakes and the related earthquake dynamics in Yunnan in the last century, we conclude that the four seismically active periods, which are characterized by alternative activity in the east and the west part of Yunnan, possibly result from a combination of active and quiescent periods in each of the east and west part. And for every 100 years, there may be a period in which strong earthquakes occur in the east and west parts simultaneously. In addition, the seismicity of strong earthquakes in Yunnan corresponds well to that in the peripheral region. The seismicity of the great earthquakes in the Andaman-Myanmar Tectonic Arc belt indicates, to some extent, the beginning of a seismically active period in Yunnan. The seismicity of strong earthquakes in east Yunnan is closely related to that in Sichuan. Strong earthquakes in Sichuan often occur later than those in Yunnan. Furthermore, in the east part of Ynnnan, the three procedures including continuous occurrence of moderate-strong earthquake, quiescent period, and the occurrence of the first strong earthquake may be the style of the beginning of the earthquake active period. The above cognition is helpful to the study of earthquake prediction, seismogenic mechanism, and the dynamics of the plate margin in Yunnan.

Comparative Analysis of Wind break and Sand fixation Functions of Several Main Forage Plants in Minqin Desert Area

[Objective] The paper was to study wind-break and sand-fixation functions of forage plants in desert area. [Method]Based on the survey data of four major wind-break and sand-fixation plants( Haloxylon ammondendron,Artemisia arenaria,Nitraria tangutorum and Ephedra przewalskii) in Minqin desert area,the longitudinal section area and the sandpile volume of an individual plant and per unit area were calculated. The wind-break and sand-fixation functions of four major plant communities were comparatively analyzed. [Result] The wind-break functions of an individual plant( cluster) successively were N. tangutorum > H. ammondendron > A. arenaria and E. przewalskii; the sand-fixation functions of an individual plant( cluster) successively were N. tangutorum > E. przewalskii; the wind-break functions per unit area successively were A. arenaria > H. ammondendron > N. tangutorum > E. przewalskii; the sand-fixation functions per unit area were N. tangutorum > E. przewalskii; the wind-break and sand-fixation function per unit area were N. tangutorum > A. arenaria > H. ammondendron >E. przewalskii.[Conclusion]A. arenaria can be selected for only wind-break,and N. tangutorum can be chosen for only sand-fixation. If given consideration to both,N. tangutorum and A. arenaria must be selected.

The Influence of Radial Area Variation on Wind Turbines to the Axial Induction Factor

Improvements in the aerodynamic design will lead to more efficiency of wind turbines and higher power production. In the present study, a 3D parametric gas turbine blade geometry building code, 3DBGB, has been modified in order to include wind turbine design capabilities. This approach enables greater flexibility of the design along with the ability to design more complex geometries with relative ease. The NREL NASA Phase VI wind turbine was considered as a test case for validation and as a baseline by which modified designs could be compared. The design parameters were translated into 3DBGB input to create a 3D model of the wind turbine which can also be imported into any CAD program. Design modifications included replacing the airfoil section and modifying the thickness to chord ratio as a function of span. These models were imported into a high-fidelity CFD package, Fine/TURBO by NUMECA. Fine/TURBO is a specialized CFD platform for turbo-machinery analysis. A code-geomturbo was used to convert the 3D model of the wind turbine into the native format used to define geometries in the Fine/TURBO meshing tool, AutoGrid. The CFD results were post processed using a 3D force analysis code. The radial force variations were found to play a measurable role in the performance of wind turbine blades. The radial component of the blade surface area as it varies in span is the dominant contributor of the radial forces. Through the radial momentum equation, this radial force variation is responsible for creating the streamline curvature that leads to the expansion of the streamtube (slipstream) that is responsible for slowing the wind velocity ahead of the wind turbine leading edge, which is quantified as the axial induction factor. These same radial forces also play a role in changing the slipstream for propellers. Through the design modifications, simulated with CFD and post-processed appropriately, this connection with the radial component of area to the radial forces to the axial induction factor, and finally the wind turbine power is demonstrated. The results from the CFD analysis and 3D force analysis are presented. For the case presented, the power increases by 5.6% due to changes in airfoil thickness only.

Risk Assessment of Tropical Cyclones to Wind Farm Operation in Northern Costal Areas of Jiangsu Province

[Objectivel The study aimed to assess the risk of tropical cyclones to wind farm operation in northem costal areas of Jiangsu Province. [Metbod] Based on tropical cyclone data during 1951 -2011 from nine national basic weather stations as well as wind data during 2005 -2007 de- termined by six gradient wind measurement towers in northern costal areas of Jiangsu Province, the spatial and temporal distribution of tropical cy- clones influencing northern coastal areas of Jiangsu Province were discussed firstly, and then the possible effects of tropical cyclones on wind farms in the northern costal areas were assessed, finally some suggestions about type selection and parameter design of wind turbines were proposed. Restult Annual average number of tropical cyclones influencing northern coastal areas of Jiangsu Province was 1.7, and the first two kinds of tropical cyclones were dominant in quantity, accounting for about 73% for total quantity. The quantity of tropical cyclones bringing substantial economic benefits to wind farms accounted for 87.7% of total quantity, with annual average quantity of 1.5. Maximum wind speed appearing every 50 years did not exceed 37.5 m/s, in accord with the national Grade-Ill standard for safe operation of wind turbines. 2.1% -3.8% of turbulence intensity ei- genvalues at a height of 70 m exceeded the maximum anti-turbulence intensity designed by IEC （0.16）, and it is suggested that anti-turbulence in- tensity parameter of wind turbines in northem costal areas of East China should be changed to 0.31 -0.41. [ Conclusion] The research could provide scientific references for design and choice of wind turbines as well as operation and management of wind farms in the study region in future.

Industrial Arrangement of Large-scale,Non-grid-connected Wind Power Industrial Zones in Coastal Areas of China

Constructing an industrial system for a large-scale,non-grid-connected wind power industry is a key step towards the diverse utilization of wind power.However,wind power exploitation is not only a technical challenge but an industrial problem as well.The objective of this study is to introduce a concept of large-scale,non-grid-connected wind power(LSNGCWP) industrial zones and establish an evaluation model to assess their industrial arrangement.The data of wind energy,industry,nature resources and socio-economy were collected in this study.Using spatial overlay analysis of geographic information system,this study proposes a spatial arrangement of the LSNGCWP indus-trial zones in the coastal areas of China,which could be summarized as the 'one line and three circles' structure,which will contribute to the optimization of the industrial structure,advance the wind power technology,coordinate the multi-industrial cooperation,and upgrade the industrial transformation of China's coastal areas.

Particle Size of Barchan Dune in Hexi Desert Area and Its Relationship with Wind Speed

[ Objective ] The paper was to study the particle size characteristics of barchan dune and its formation mechanism in Hexi desert area d Gansu. [ Method] Through particle size measurement and wind speed flow field observation d dune, the particle size differences of various sampling plots and various parts of dune were analyzed using analysis of variance, and the relationship between particle size and wind speed was analyzed using correlation coefficient method. [ Result] （ 1 ） Barehan dune and barehan chains in Hexi desert area of Gansu were mainly consisted of fine sands and medium sands at the depth of 0 -5 cm： the sand particle in Gulang desert area was fine, which had significant difference with that in Jinchang, Linze, Jinta and Minqin desert areas. （2） Medium sands gradually increased from the bottom of windward slope to the dune peak in both barchan dune and barchan chain. On the windward slope of barehan dune, fine sands gradual- ly increased from the middle to both sides, while coarse sands and medium sands gradually decreased. On the windward slope of barehan chain, fine sands first de- creased then increased from the middle to NE side, but first increased then decreased from the middle to SW side. （3） In terma of particle size, there were great variations between fine sands and coarse sands ; for dune parts, there were great variations between dune peak and leewant slope toe; for dune types, the variation of fine sands in various parts of barchan chain was greater than that of barchan dune, while differentiation degree of medium sands and fine sands was greater than that of barchan dune. The particle size of fine sands was positively correlated with wind speed, and that of medium sands was negatively correlated with wind speed. [ Conclusion] The formation environment of particle size of berehan dune mainly included sand source and dynmnic source, and wind speed was the dynamic source for particle size distribution of barchan dune.

THE ANALYSIS ON THE STATISTICAL CHARACTER OF QUIKSCAT SCATTEROMETER WINDS AND STRONG WIND FREQUENCY USING REMOTE SENSOR DATA FROM QUIKSCAT

The statistical character of QuikSCAT scatterometer winds is showed. And Monthly change and special distribution character of strong wind frequency and monthly wind fields in South China Sea is analyzed. It is shown in the result that the QuikSCAT scatterometer winds can be relied upon for the South China Sea; two winds, one the wintertime northeasterly and the other summertime southwesterly. The northeasterly centers at the Bashi Strait and Taiwam Strait and its secondary center and the maximum center of the southwesterly are in the central and southern South China Sea.

Short-Term Reliability Evaluation of Transmission System under Strong Wind and Rain

The impact of strong wind and rain loads will adversely affect the reliability of the overhead lines, it’s necessary to study changes in risk of transmission system and establish the reliability model of overhead lines through the strong wind and rain loads. In this article, the stochastic properties of overhead lines’ strength and loads were used, according to principles of structural reliability, time-dependent failure probability model of overhead lines was established under the impact of strong wind and rain loads. Simulation of the IEEE-79 system demonstrates that failure probability model is effective. This simulation result also shows that the impact of strong wind and rain loads will seriously affect reliability indices of system loads, rain loads cannot be ignored under strong wind and rain loads.