A Wind Tunnel Simulation of Windproof Effectiveness of Simulated Shrubs with Different Spatial Configurations

<p>A better understanding of the distribution of the airflow field and wind velocity around the simulated shrubs is essential to provide optimized design and maximize the efficiency of the windbreak forests. In this study, a profiling set of Pitot Tube was used to measure the airflow field and wind velocity of simulated shrubs by wind tunnel simulation. The effects of form configurations and row spaces of simulated shrubs on windproof effectiveness were in-depth studied. We come to the following results: The weakening strength to wind velocities of hemisphere-shaped and broom-shaped shrubs at 26.25 cm was mainly concentrated below 2 cm near the root and 6-14 cm in the middle-upper part, while the spindle-shaped shrubs were at 0.2-14 cm above the canopy, which meant the windproof effect of spindle-shaped shrubs was was better than that of hemisphere-shaped and broom-shaped. With the improvement of row spaces, the weakening height to wind velocities of the hemisphere-shaped shrubs at 35 cm was only concentrated below 2 cm near the root exclude for the 6-14 cm at 26.25 cm, which presented the hemisphere-shaped shrubs were not suitable for the layout of wide row space. Further, the form configurations of simulated shrubs had a stronger influence on wind velocity than row spaces. Moreover, the designed windbreaks with <em>Nitraria tangutorum</em>, which more effectively reduced the wind velocity among the windbreaks compared to behind the windbreaks. In the wind control system, the hemisphere-shaped windbreaks should be applied as near-surface barriers, and the windbreaks of broom-shaped and spindle-shaped can be used as shelterbelts above the near-surface. These analytical findings offer theoretical guidelines on how to arrange the windbreak forests for preventing wind erosion in the most convenient and efficient ways.</p>

Wind-Tunnel Simulation of Approximately Horizontally Homogeneous Stable Atmospheric Boundary Layers

Two cases of an overlying inversion imposed on a stable boundary layer are investigated, extending the work of Hancock and Hayden (Boundary-Layer Meteorol 168:29–57, 2018; 175:93–112, 2020). Vertical profiles of Reynolds stresses and heat flux show closely horizontally homogeneous behaviour over a streamwise fetch of more than eight boundary-layer heights. However, profiles of mean temperature and velocity show closely horizontally homogeneous behaviour only in the top two-thirds of the boundary layer. In the lower one-third the temperature decreases with fetch, directly as a consequence of heat transfer to the surface. A weaker effect is seen in the mean velocity profiles, curiously, such that the gradient Richardson number is invariant with fetch, while various other quantities are not. Stability leads to a ‘blocking’ of vertical influence. Inferred aerodynamic and thermal roughness lengths increase with fetch, while the former is constant in the neutral case, as expected. Favourable validation comparisons are made against two sets of local-scaling systems over the full depth of the boundary layer. Close concurrence is seen for all stable cases for z/L < 0.2, where z and L are the vertical height and local Obukhov length, respectively, and over most of the layer for some quantities.

Wind Dynamic Environment and Wind Tunnel Simulation Experiment of Bridge Sand Damage in Xierong Section of Lhasa–Linzhi Railway

The Lhasa–Linzhi Railway is located in the sandy area of the South Tibet valley, with high elevation and cold temperature. The Xierong section is a bridge section where blown sand hazards are severe. However, the disaster-causing mechanism of blown sand hazards in this section is currently unclear, thereby hindering targeted sand prevention and control. To address this problem, the wind dynamic environment of and causes of sand damage in this section are investigated through the field observation of the locale and a wind tunnel simulation experiment. Results show that the dominant sand-moving wind direction in the Xierong section is SSE. The wind speed, frequency of sand-moving wind, sand drift potential (DP), and maximum possible sand transport quantity (Q) in this section are relatively high during spring (March to May) and low during other seasons. The yearly resultant sand transport direction (RDD, RA) is SW. The angle between the route trend of this section and the sand transportation direction is 30°–45°, and the sand source is located in the east side of the railway. During spring, sand materials are blown up by the wind, forming blown sand flow and movement from the NE to SW direction. Increased wind speed area is formed between the top of the slope shoulder of the windward side of the bridge and the downwind direction of 3H, causing blown sand erosion. Meanwhile, weakened wind speed areas are formed within the distance of -3H at the upwind direction and from the downwind direction of the 3H to 20H of the bridge. These areas accumulate sand materials at the upwind and downwind directions of the bridge, thereby resulting in blown sand hazards. This research provides a scientific basis for the prevention and control of sand damage in the locale.

Heat Exchangers Modeling using Industrial Wind Tunnel Simulation for Automobile Industry

In the industry 4.0 eras, it is necessary to analyze each parameter precisely. In case of heat transfer studies, the automobile and aerodynamic industry is gaining more and more attention. Many heat exchangers are designed and tested in industry but for any specific product thermal characteristics can be different which depends on the scenario of use of that product. Heat exchangers can test with fluid, air etc. For internal machines like bearing cooling fluid can be used but in case of automobile, aerodynamics air flow is important element. This paper presents the simulation and analytical modeling of various heat exchangers. This can be very useful for lowering the insulation damages or foil damages of vehicle. The wind tunnel test is carried with constant wind flow to assure that vehicle speed and cooling can be moderate without issue of cooling.

ANALYSIS OF JIAYUGUAN [嘉峪关] PAVILIONS' DEFORMATION AND ITS INFLUENCE FACTORS WITH THE APPLICATION OF COMPREHENSIVE TECHNOLOGY

<p><strong>Abstract.</strong> In the case study of Guanghua Pavilion [光化楼] located in Jiayuguan [嘉峪关] City, Gansu province in China, the 3D laser scanning technology and leveling technology are used to analyze overall tilt, columns tilt and uneven settlement of the pavilion. It is found that Guanghua Pavilion [光化楼] tilted to the southeast; most of the columns from the first floor to the third floor tilted to the northeast and east directions, and all the tilted distance of the columns is within 100 mm.; a certain amount of uneven settlement happened on Guanghua Pavilion [光化楼], in which the east side sinks more obviously. In the process of analyzing the influencing factors of deformation, numerical wind tunnel simulation and Midas Gen modeling methods are used. It is concluded that the external wind load is the main cause of Jiayuguan [嘉峪关] pavilions’ deformation.</p>