Vortex Characteristics of Heliostats’ Surface Wind Pressure under Resting Condition

2014 ◽  
Vol 953-954 ◽  
pp. 1463-1466
Author(s):  
Ying Ge Wang
Keyword(s):  
Flow Field ◽  
Surface Wind ◽  
Point Vortex ◽  
Wind Pressure ◽  
Vortex Model ◽  
Columnar Vortex ◽  
Flow Field Characteristics ◽  
Fluctuating Wind ◽  
Conical Vortex ◽  
Surface Vortex

Flat rectangular heliostats’ surface wind pressure distribution under resting condition was analyzed via wind tunnel experiment results. The flow field characteristics of the mirror in parallel with the ground were combined to reveal the distribution cause of fluctuating pressure. Phenomena of columnar vortex and conical vortex formed from mirror’s flow field under wind angles 0° and 45° were aimed to explain their internal structure using theory of point vortex model. With power spectrum of peculiar points’ fluctuating wind pressure analyzed, the surface vortex characteristics were further elaborated. The above work revealed heliostats’ surface wind pressure characteristics under resting conditions, and established the theoretical basis of its design study.

scholarly journals Study on Flow Field Characteristics of the 90° Rectangular Elbow in the Exhaust Hood of a Uniform Push–Pull Ventilation Device

2018 ◽  
Vol 15 (12) ◽  
pp. 2884 ◽  
Author(s):  
Xiang Wu ◽  
Lindong Liu ◽  
Xiaowei Luo ◽  
Jianwu Chen ◽  
Jingwen Dai
Keyword(s):  
Flow Field ◽  
Wind Velocity ◽  
Cfd Simulation ◽  
Distribution Patterns ◽  
Wind Pressure ◽  
Radius Of Curvature ◽  
Control Effect ◽  
Material Loss ◽  
Average Wind ◽  
Flow Field Characteristics

A uniform push–pull ventilation device can effectively improve indoor air quality (IAQ). The 90° rectangular elbow is an important part of the push–pull ventilation device. This paper analyzes the flow field characteristics of the 90° rectangular elbows under different working conditions. This was done by using computational fluid dynamics (CFD) simulation (Fluent). The flow lines, velocity and pressure distribution patterns of the elbow flow field are revealed in detail. The wind velocity non-uniformity and wind pressure non-uniformity of the 90° rectangular elbows with different coefficients of radius curvature R and rectangular section height h are also compared. The results show that when R ≥ 2.5 h, the wind flow traces inside the elbow are basically parallel lines. At the same time, the average wind velocity and the average wind pressure are stable. Also, the wind velocity non-uniformity and wind pressure non-uniformity decrease with the increase of R. Therefore, considering the space and material loss caused by an increase in radius of curvature, the elbow with R = 2.5 h can be used as the best design structure for the 90° rectangular elbow, which is of great significance for improving the control effect of dust and toxic pollutants in a uniform push–pull ventilation device.

Wind Pressure and Wind-Induced Vibration of Heliostat

2008 ◽  
Vol 400-402 ◽  
pp. 935-940 ◽  
Author(s):  
Ying Ge Wang ◽  
Zheng Nong Li ◽  
Bo Gong ◽  
Qiu Sheng Li
Keyword(s):  
Dynamic Response ◽  
Wind Direction ◽  
Wind Load ◽  
Wind Pressure ◽  
Induced Response ◽  
Vertical Angle ◽  
Lateral Direction ◽  
Direction Angle ◽  
Wind Pressures ◽  
Fluctuating Wind

Heliostat is the key part of Solar Tower power station, which requires extremely high accuracy in use. But it’s sensitive to gust because of its light structure, so effect of wind load should be taken into account in design. Since structure of heliostat is unusual and different from common ones, experimental investigation on rigid heliostat model using technology of surface pressure mensuration to test 3-dimensional wind loads in wind tunnel was conducted. The paper illustrates distribution and characteristics of reflector’s mean and fluctuating wind pressure while wind direction angle varied from 0° to 180° and vertical angle varied from 0° to 90°. Moreover, a finite element model was constructed to perform calculation on wind-induced dynamic response. The results show that the wind load power spectral change rulers are influenced by longitudinal wind turbulence and vortex and are related with Strouhal number; the fluctuating wind pressures between face and back mainly appear positive correlation, and the correlation coefficients at longitudinal wind direction are smaller than those at lateral direction; the fluctuating wind pressures preferably agree with Gaussian distribution at smaller vertical angle and wind direction angle. The wind-induced response and its spectrums reveal that: when vertical angle is small, the background responsive values of reflector’s different parts are approximately similar; in addition, multi-phased resonant response occurring at the bottom. With the increase of , airflow separates at the near side and reunites at the other, as produces vortex which enhances dynamic response at the upper part.

scholarly journals Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 97
Author(s):  
Junfeng Sun ◽  
Meihong Liu ◽  
Zhen Xu ◽  
Taohong Liao ◽  
Xiangping Hu ◽  
...  
Keyword(s):  
Flow Field ◽  
Film Thickness ◽  
Fluid Dynamic ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
High Rotational Speed ◽  
Flexible Support ◽  
Flow Field Characteristics

A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.

scholarly journals Influence of Vortex Finder Structure on Separation Performance of Double-Overflow Three-Product Hydrocyclones

Separations ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 79
Author(s):  
Yuekan Zhang ◽  
Jiangbo Ge ◽  
Lanyue Jiang ◽  
Hui Wang ◽  
Junru Yang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Experimental Research ◽  
Separation Efficiency ◽  
Structural Parameters ◽  
Separation Performance ◽  
Insertion Depth ◽  
Flow Field Characteristics ◽  
Vortex Finder ◽  
Fine Classification

In view of the difficulty of traditional hydrocyclones to meet the requirements of fine classification, a double-overflow three-product (internal overflow, external overflow and underflow) hydrocyclone was designed in this study. Numerical simulation and experimental research methods were used to investigate the effects of double-overflow flow field characteristics and structural parameters (i.e., internal vortex finder diameter and insertion depth) on separation performance. The research results showed that the larger the diameter of the internal vortex finder, the greater the overflow yield and the larger the cut size. The finest internal overflow product can be obtained when the internal vortex finder is 30 mm longer than the external vortex finder. The separation efficiency is highest when the internal vortex finder is 30 mm shorter than the external vortex finder.

scholarly journals Design of a Double-Nozzle Air Spray Gun and Numerical Research in the Interference Spray Flow Field

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 475
Author(s):  
Yin-An Wang ◽  
Xiao-Peng Xie ◽  
Xiao-Hui Lu
Keyword(s):  
Flow Field ◽  
Central Region ◽  
Interference Effect ◽  
Thickness Distribution ◽  
Computational Domain ◽  
Coating Film ◽  
Discrete Phase Model ◽  
Spray Painting ◽  
Flow Field Characteristics ◽  
Spray Gun

Spray painting robots equipped with air spray guns have been widely used in the painting industry. In view of the low efficiency of single-nozzle air spray guns when spraying large targets, a new double-nozzle air spray gun structure was designed in this paper based on the Coanda effect of double jets. Firstly, a 3-D physical model of the double-nozzle air spray gun was built in Solidworks, in which unstructured grids were generated for the computational domain by ICEM. Secondly, the spray painting process was numerically modeled with the help of the computational fluid dynamics (CFD) software ANSYS-Fluent 16.0. The two-phase spray flow was calculated by coupling a discrete phase model (DPM) and the Taylor analogy breakup (TAB) method. The TAB model was applied to predict the secondary break-up. The DPM model was applied to predict the droplet trajectories. The geometry of an air spray gun has a significant influence on the spray flow field characteristics. The influence of the air spray gun geometry on the interference spray flow field characteristics and coating film thickness distribution were investigated by changing the values of the distance between the centers of the two paint holes (L) and the angle between the axes of the two paint holes (θ). Numerical results show that the smaller L and θ are, the stronger the interference effect between the two jets, while the more concentrated the paint is in the central region of the target surface, the easier it is for overspray to occur. With increasing L and θ, the interference effect gradually decreased and the extension distance of the coating film along the x-axis gradually increased. However, if L and θ are too large, the interference effect will become too weak and the shape of the coating film will become a concave, with more paint on both side regions and less paint in the central region, which will cause an uneven coating film. From the simulation results, it can be concluded that a more uniform coating film can be obtained when L = 30 mm and θ = 10°. The effective coating width of the double-nozzle air spray gun was increased by 85.7% compared with the single-nozzle air spray gun, which improved the spraying efficiency.

Effects of Flue Gas Inlet Structure on the Flow Field Characteristics of Multi-Stage Liquid Column Scrubber

2013 ◽  
Vol 773 ◽  
pp. 749-754
Author(s):  
Zhen Ya Duan ◽  
Fu Lin Zheng ◽  
Hui Ling Shi ◽  
Jun Mei Zhang
Keyword(s):  
Flow Field ◽  
Flue Gas ◽  
Static Pressure ◽  
Liquid Column ◽  
Liquid Distribution ◽  
Multi Stage ◽  
Flow Field Characteristics ◽  
Wall Flow ◽  
Two Peaks ◽  
Saddle Shape

In this paper, the numerical model of multi-stage liquid column scrubber was established. The flow field of liquid column scrubber with different inlet structure was respectively simulated by a commercial CFD code, Fluent. Considering the distribution characteristics of static pressure and velocity in the scrubber, this inlet type, single horizontal gas inlet with a notch at the bottom, is regarded as the most reasonable structure. On one hand, that structure has uniform distribution of static pressure. On the other hand, the velocity profile of its field presents saddle shape, i.e. the low central velocity exists between two peaks, which could contribute to weakening wall-flow phenomenon and obtaining uniform gas-liquid distribution.

A simple point vortex model for two‐dimensional decaying turbulence

1992 ◽  
Vol 4 (5) ◽  
pp. 1036-1039 ◽  
Author(s):  
R. Benzi ◽  
M. Colella ◽  
M. Briscolini ◽  
P. Santangelo
Keyword(s):  
Point Vortex ◽  
Two Dimensional ◽  
Simple Point ◽  
Vortex Model ◽  
Decaying Turbulence ◽  
Point Vortex Model
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