Suction Wind Research Articles

Experimental investigation into the effects of endplate designs for a Savonius turbine

Abstract Wind energy is experiencing a trend of exponential growth in both literature and industrial employment, emphasizing its current pivotal role in achieving carbon neutrality by replacing fossil fuels. Vertical axis wind turbines (VAWTs) particularly Savonius rotors operate at a lower tip-speed-ratio (TSR) range compared to horizontal axis wind turbines (HAWTs). The Savonius rotor has good starting characteristics, making it suitable to be placed in urban areas with lower wind speeds. Due to its low efficiency, studies on augmentation and optimization have been conducted to improve its blade and deflector designs. Extensive research has established a common consensus that the use of endplates significantly improves the aerodynamic performance of the Savonius rotor. However, limited research has been undertaken to explore the endplate design further. In this study, wind tunnel tests were conducted on different endplate ratios, to investigate the effects of endplate design on the aerodynamic performance of a conventional Savonius turbine. Three different Savonius rotor with no endplate, semi-circular endplate and circular endplate were designed and manufactured. Experiments were conducted in an open-type suction wind tunnel at a constant measured wind velocity of 5.89 m/s. The turbine’s performance for different endplate ratios was evaluated across a TSR range of 0.2 to 1.0. The performance was assessed based on the maximum power generated and its self-starting ability. From the experimental results, the circular endplate ratio of 1.1 shows a significantly high coefficient of power compared to both semi-circular and without endplates. This is due to reduced spanwise spillage and enhanced airflow capture by the rotor. The endplates direct incoming air to the advancing blade and overlap region, resulting in the increased pressure difference between the concave and convex sides of both the advancing and returning blade, thereby improving the power efficiency of the turbine with 1.1D diameter endplate and semi-circular endplate by 296.6% and 6.9% compared to no endplates case.

Development of a Simple and Stable NanoESI Spray System Using Suction Wind from the MS Inlet.

Improving the reproducibility of proteome analysis systems presents a challenge; therefore, in this study, we developed a new insertion spray ionization (InSpIon) system wherein an InSpIon tube was designed with a spray tip inserted into the tube. This system stabilized the spray and subsequently improved the reproducibility of the analysis.

Aerodynamic and Acoustic Properties of a Vertical Suction Wind Tunnel Guide Vane

The paper presents tests of wind tunnel guide vanes with glass-fiber wool for reducing the airflow pressure loss and noise between the intake tower of a vertical suction wind tunnel and the corner of its section. After installing a double-arc airfoil guide vane with glass-fiber wool inside at the corner and determining how the guide vane influences the wind tunnel airflow through computer simulation, the numerical results showed that with seven double-arc airfoil guide vanes, the airflow pressure loss was reduced by 62%, the corner vortex was eliminated, and the flow field uniformity was improved. Furthermore, the loss of noise transmission in the wind tunnel with glass-fiber wool was simulated with different software. The results showed that the maximum noise absorption was 57.8 dB. Additionally, the average noise absorption was 31.9 dB when the windward side of the guide vane was a 5-mm-diameter perforated plate with a 0.3 porosity rate, and the internal filling with glass-fiber wool has a flow resistance of 4,896 Pa·s/m2. Finally, a simulation of the perforated guide vanes was carried out, and the results showed that the perforated guide vanes improved the aerodynamic performance of the wind tunnel by 18.6% compared with the wind tunnel without the guide vanes. The research results can provide a reference for the multifunctional design of wind tunnel guide vanes.

Analisis Perkuatan Rangka Atap Baja pada Bangunan Gedung Heritage 1921 Menggunakan Software SAP 2000

Introduction: The roof truss construction used in the cultural heritage building in this analysis is a truss roof truss with 2L angle steel profiles (double elbow) 40.40, 50.50, 60.60, 70.70, IWF steel profile gording 150x150, and roof tile coverings, with a length ofroof 102 m, width 21.6 m, height 5 m, with a distance of 7.4 m and 4.1 m truss. The cultural heritage building discussed in this analysis is the roof, namely the horses. Method: The method used in this study is to collect data in the form of shop drawings. The purpose of the study was to identify the capability of the roof structure with the updated loading regulations RSNI 1727-2018. Results: This analysis uses the latest RSNI 1727-2018 loading regulations and the latest SNI 1729-2015 steel regulations, does not change the installed materials and existing shapes, and does not use earthquake and rain loads, only live/maintenance loads, heavy dead loads. roof coverings, ceilings and hangers, and compressed and suction wind loads. Conclusion: From the resultsof this analysis, it is assumed that the rusted steel profile has been replaced, there are two truss rods that need to be replaced with a 2L 80.80 double angled profile with initial data of a 70.70 2L profile. Analysis of the 3-dimensional roof structure with SAP2000 software by reviewing the dead load, the live load of workers according to the loading regulations of the RSNI 1727-2018, taking into account the compressed wind load of 75.82 m2, the suction wind load of 57.37 m2 according to the wind speed of 40 m/s

Orthogonal optimization for effective classification of different tea leaves by a novel pressure stabilized inclined chamber classifier

AbstractIn the field of tea separation and processing, modern high‐tech can realize the nondestructive separation of tea and improve the quality of tea. In this study, a novel pressure‐stabilizing inclined chamber classifier was proposed, which was used to adjust the particle size distribution of tea at the entrance of the classifier. A suitable cavity can control the change of wind speed so that tea leaves are not easy to bend and deform, and the success rate of grading is improved. Second, three parameters that affect the success rate of tea classification are put forward: suction wind speed V, suction distance H, and suction distance L. When the parameters are V = 6 m/s, H = 40 mm, and L = 20 mm, the best response value is obtained, thus the most suitable entrance shape is obtained. Finally, the internal flow field of the classifier is analyzed, and different sizes of tea leaves are classified according to the change of air pressure flowing through the closed structure cavity. With the distribution of air velocity, tea leaves fall into collectors with different widths. Therefore, the flow field simulation test shows that the classifier can classify high‐quality tea according to the airflow. The model lays a foundation for further study of the fluid–solid coupling process and interaction between particles.Practical ApplicationsIn this study, a novel pressure‐stabilized inclined chamber classifier was designed, and three parameters that affect the success rate of tea classification were put forward. The process conditions were optimized by orthogonal tests, and the number of experiments was reduced. This method can be used to evaluate the influence of various technological parameters on tea classification. In order to improve the classification success rate, it is necessary to statistically discuss the results of the orthogonal test and flow field analysis.

Experimental investigation of geometry effects and performance of five-hole probe in measuring jets in crossflow

Vortical and shear flows are common in turbomachinery. Multi-hole pressure probes are used in turbomachinery flows in order to provide robust and accurate measurements of both pressure and velocity components. In this study, two different miniature five-hole probes are designed and fabricated, both with a cobra shape. The probe tip was 1.45 mm and it was maintained in that size for the length of the cobra shape formation, providing very close proximity to the solid boundaries and reduced flow blockage. The difference among the probes corresponded to the head geometry, as the one probe was formed with a pyramid tip shape, while the other was maintained with a flat shape. The calibration process was carried out in an open-circuit suction wind tunnel for the range of ±32⁰ in yaw and pitch direction. The results showed that the pyramid probe exhibits a high flow angle spatial sensitivity and a reliable measurement range of ±28⁰ in yaw and pitch direction. The flat probe provided unexpected well angle sensitivity and reliable measurements data despite the fact that it is of a very simple form. The pyramid probe showed superior performance. In particular, the pyramid probe offers 12.5% wider operating range. In order to prove the effectiveness of the pyramid probe, measurements were obtained in a jet in cross flow. In order to evaluate the performance of the probe, further, a surface fit model was employed to produce ideal calibration coefficients. These were used to redefine the magnitude of the velocities in the measured flow domain. The accuracy in measurements was assessed, comparing the velocities produced by the two variants of pressure coefficients. The results indicate that the pyramid probe operates reliably in a very large range of constantly changing velocity vector, which occurs in jet in cross flow.

Experimental Investigation of Wash Fluid Preheating on the effectiveness of online Compressor Washing in a Suction Tunnel Compressor Cascade

Online compressor washing is a promising method of preventing/ recovering the effects of fouling on the compressor blades. However, proper strategies need to be implemented for online compressor washing to be effective since it is conducted when the engine is in operation. This study presents an experimental investigation of wash fluid preheating on the effectiveness of online compressor washing in a suction wind tunnel compressor cascade. Crude oil was uniformly applied on the compressor cascade blade surfaces using a roller brush, and carborundum particles were ingested into the tunnel to create accelerated fouled blades. Demineralized water was preheated to 500C using the heat coil provided in the tank. Washing of the fouled blades were conducted using single flat fan nozzle, where the preheated and non preheated demineralized water were used separately to wash the fouled blades. When fouled blades washed with preheated demineralized and the non-preheated were compared, it was observed that there was little or no difference in terms of total pressure loss coefficient and exit flow angle. However, when the fouled and washed cases were compared, there was a significant difference in total pressure loss coefficient and exit flow angle.

Numeričko i eksperimentalno određivanje opterećenja koje vetar vrši na sklopove fotonaponske ploče

The article presents the aerodynamic study of solar panel assemblies and determination of wind load. In the first part, the task is solved by computer simulation of the wind flow around the proposed rectangular assembly in the scale of 1:1 using the FLUENT ANSYS program; realization of experimental measurements in the wind tunnel with a boundary layer (BLWT) in Bratislava is presented subsequently. The aim of the solution was to determine the maximum pressure and suction wind load on top and bottom surfaces of panels. The resulting net pressure coefficient represents the maximum local pressure in each panel row as maximum values from all wind directions. The experimentally obtained net pressure coefficient values were compared with computer simulation and the procedures mentioned in standard STN EN 1991-1-4. It can be seen that the inner panels are loaded considerably less than the standard defines. The panels placed on the side of the assembly or on the edge of the aisle are loaded significantly more than the standard defines. Frontal panels are also less wind stressed than in the standard defines.

Experimental determination of wind action on triangular solar panel assemblies

The article deals with aerodynamic study of solar panel assemblies. Experimental measurements were realized in BLWT wind tunnel. The aim of the solution was to determine the maximum pressure and suction wind load on top and bottom surfaces of panels. The resulting net pressure coefficient represents the maximum local pressure in each panel row as maximum values from all wind directions. The experimentally obtained cp,net values were compared with the conservative values in EN 1991-1-4 for open monopitch canopies. A lower wind load in the inner regions of the triangular assemblies should be used in the design of fixing supports.

An example of industrialization of melt electrospinning: Polymer melt differential electrospinning

Abstract In recent years, researchers are paying more attention to high efficiency, high process stability and eco-friendly nanofiber fabrication techniques. Among all of the nanofiber fabrication methods, electrospinning including solution electrospinning and melt electrospinning is the most promising method for nanofiber mass production. Compared to solution electrospinning, melt electrospinning could be applied in many areas such as tissue engineering and wound dressings due to the absence of any toxic solvent involvement. Capillary melt electrospinning generates only one jet with low efficiency. Hence, we have proposed polymer melt differential electrospinning (PMDES) method, which could produce multiple jets with smallest interjet distance of 1.1 mm from an umbrella shape spinneret, thus improving the production efficiency significantly. Many techniques such as material modification, suction wind, and multistage electric field were proposed to refine the fibers and nanofibers with average diameter of about 300 nm were obtained. Scale up production line of PMDES with capacity of 300–600 g/h was established by arraying umbrella shape spinnerets. PMDES is a promising technology to meet the requirements of nanofiber production in commercialization.

Effects of Lip Thickness on the Flowfield Structures of Supersonic Film Cooling

Schlieren visualizations of flowfield structures of supersonic film cooling in a backward-facing step were conducted in a Mach 2.95 suction wind tunnel with the film coolant tangentially ejected through half-Laval nozzles, all of which were designed in Mach 1.5 but with different lip thicknesses. The film coolants were fed with pressures matching the mainstream, and the flowfield changes of supersonic film cooling under different lip thicknesses between the slot and mainstream were clearly visualized under the conditions of the same step and slot heights. When the step height was kept the same, an increase in lip thickness decreased the angle of the shock wave emanating from the upper tip of the lip, and it decreased the strength of the reattachment shock wave when it was larger than a certain value. When the slot height was kept the same, the increase in lip thickness tended to decrease the angles of the shock waves emanating from the upper and lower tips of the lip and reattachment shock waves. This work provides an in-depth understanding of the flowfields of supersonic film cooling near the backward-facing step and may be used as a reference for the design of supersonic film cooling.

Influence of processing parameters on fibers diameter and web evenness of polypropylene spunbonding nonwoven fabrics in wide slot positive pressure drafting assembly of spunbonding process

The air drawing model of polymer polypropylene (PP) spunbonding nonwovens has been established. The influences of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter have been studied. The air drawing model of polymer in spunbonding is confirmed by the experimental results obtained with our university's equipment. The effects of the processing parameters on fibers web evenness of PP spunbonding nonwoven fabrics in wide slot positive pressure drafting assembly of spunbonding process have also been investigated. The predictions of the filament fiber diameters, crystallinities, and birefringences are coincided well with the experimental data. It is found that a medium polymer melt temperature, monomer suction wind speed, drawing pressure, cross air blow speed, and air control distance have a significant influence on the web evenness and quality, which are beneficial to produce more uniformity fibers web. The experimental results show that the agreement between the results and experimental data is very better, which verifies the reliability of these models. At the same time, the results also reveal the great potential of this research for the computer‐assisted design (CAD) of spunbonding technology. POLYM. ENG. SCI., 58:1268–1277, 2018. © 2017 Society of Plastics Engineers

07.05: Fatigue life assessment of cold‐formed steel roof battens

ABSTRACTMetal roofs of low‐rise buildings are exposed to highly fluctuating and prolonged suction wind uplift pressures during cyclones. The high suction pressures on roofs lead to premature, low cycle fatigue failures of roof members. Steel roof batten made of thin, high strength cold‐formed steel (CFS) is one of the vulnerable roof members that fails prematurely during cyclones. Pull‐through failure in the vicinity of batten to rafter connection is one of its common failure modes. A preliminary study on this topic revealed that the fatigue pull‐through capacity of a commonly used industrial roof batten is 45% of its static pull‐through capacity. Therefore, in order to assess the fatigue capacity and performance of all available CFS roof battens, a series of constant amplitude cyclic tests was conducted on thin‐walled steel roof battens. Critical parameters which influence the pull‐through failure, such as the steel batten grade, thickness and screw fastener diameter, were considered in the test series. S‐N curves were developed for each combination of the selected critical parameters, and the respective fatigue limits were obtained. Test results led to a simple modification to the recently developed static pull‐through capacity equations in order to include the effects of fatigue. They also improved the understanding of the fatigue behaviour of roof battens. In addition, a series of multi‐level cyclic tests was included in this study to investigate the suitability of the currently available Low‐High‐Low (LHL) cyclic test method. This paper presents the details of this study, and the results.

Experimental investigation and a novel analytical solution of turbulent boundary layer flow over a flat plate in a wind tunnel

The fluid mechanics of incompressible turbulent boundary layers air flow over a flat plate is investigated using an open-ended suction wind tunnel. The wall shear stress is measured by a distinct method using Thin-Oil-film technique in order to determine skin friction of the plate. On theoretical side, the governing partial differential equations are transformed to an ordinary differential equation with inconsistent coefficients using similarity variables and they are solved by variational iteration method. The distribution of the velocity, friction coefficient and thickness of the boundary layer are obtained analytically and experimentally, and compared with the previously reported results, where good agreements are observed. New correlations for skin friction coefficient and boundary layer thickness of turbulent flow over flat plate are proposed.

C&C efficiency of canopy hood exposed to horizontal air stream in commercial kitchen calculated by CFD analysis

ABSTRACTAs one of the commercial kitchen ventilation researches, the mechanism of capture phenomenon and containment one of a canopy hood has to be investigated. Several experiments intended to change the Capture and Containment (C&C) efficiency of combustion gas and cooking effluence were conducted under the conditions of different suction wind velocity at the bottom of a hood, sometimes called face velocity, which is caused by the different hood size. The overall C&C efficiency was analyzed by means of computational fluid dynamics (CFD). The C&C efficiency from the experiment and CFD analysis showed good agreement, and it was assumed that the disturbing ambient airflow around the hood can influence on the C&C efficiency. Therefore the kitchen space was assumed which includes the disturbing airflow over the counter between a dining hall and a kitchen. As a result, the C&C efficiency of the larger hood decreased more under the disturbing airflow.

Continuous manufacturing of nanofiber yarn with the assistance of suction wind and rotating collection via needleless melt electrospinning

ABSTRACTNanofiber yarn was continuously manufactured by a needleless melt‐electrospinning method. The suction wind speed was the most important factor influencing the final fiber diameter and determining whether the fibers could be gathered into a well‐aligned strand. The twisting process of the yarn was performed by the adjustment of ratio of the speed of the collecting roller to the speed of the rotating disk. The results show that the higher the assisting suction wind speed was, the smaller the fiber diameter was. The smallest average fiber diameter of 440 nm was obtained at a suction wind speed of 30 m/s. Furthermore, the smaller the ratio of the speed of the collecting roller to the speed of the rotating disk was, the larger the twisting angle of the prepared yarn was. The largest twisting angle obtained in this study was 43 ° at the greatest ratio of the speed of the collecting roller to the speed of the rotating disk. The X‐ray diffraction results show that the alignment degree of the nanofiber twisting and the crystallinity increased with increasing twisting angle. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44820.

Analysis of Turbulent Flow over a 90° Bend of Duct Using In Centralized A. C. Plant by CFD Code

*Corresponding Author: mukeshdidwania4u@gmail.com Abstract: This test case was calculated using a commercial finite volume CFD computer code ANSYS 12.0 Fluent. The geometry of Model is a three-dimensional turbulent flow over a 90° bend. Experimental setup comprising an open-circuit suction wind tunnel system for the 90° bend which is used in ducting of centralized A. C. plant in various buildings or Malls. This test case focuses on the use of approximate models such as the turbulence models to predict the physical characteristics of the turbulent flow around a 90° bend. The results from the more sophisticated Reynolds stress model are shown to better capture the anisotropy behavior of the flow in contrast to the standard k-e model that assumes isotropy in its original model formulation and also k-w SST model use to comparison. Finite Volume Discretization (FVM) is employed to approximate the governing equation. Velocity and pressure distribution at bend show by simulation of fluent CFD Code. By increasing the bend length in duct, losses can be reduce.

Experimental and Numerical Study of Dilute Gas-Solid Flow inside a 90° Horizontal Square Pipe Bend

A pneumatic test rig is built to test a curved 90° square bend in an open-circuit horizontal-to-horizontal suction wind tunnel system. Sand particles are used to represent the solid phase with a wide range of particle diameters. Velocity profiles are constructed by measuring the gas velocity using a 3-hole probe. Flow patterns inside the bend duct are introduced using sparks caused by burning sticks of incense with the air flow inside the piping system for flow visualization purpose. Numerical calculations are performed by Lagrangian-particle tracking model for predicting particle trajectories of dispersed phase, and standard k-ε model for predicting the turbulent gas-solid flows in bends. Comparisons made between the theoretical results and experimental data for the velocity vectors and particle trajectories show good agreement.

Joint Computational/Experimental Aerodynamic Study of a Simplified Tractor/Trailer Geometry

Steady-state Reynolds averaged Navier–Stokes (RANS) simulations are presented for the three-dimensional flow over a generic tractor trailer placed in the Auburn University 3×4 ft2 suction wind tunnel. The width of the truck geometry is 10 in., and the height and length of the trailer are 1.392 and 3.4 times the width, respectively. The computational model of the wind tunnel is validated by comparing the numerical results with the data from the empty wind tunnel experiments. The comparisons include the boundary layer properties at three different locations on the floor of the test section and the flow angularity at the beginning of the test section. Three grid levels are used for the simulation of the truck geometry placed in the test section of the wind tunnel. The coarse mesh consists of 3.4×106 cells, the medium mesh consists of 11.2×106 cells and the fine mesh consists of 25.8×106 cells. The turbulence models used for both the empty tunnel simulations and the truck geometry placed in the wind tunnel are the standard Wilcox 1998 k-ω model, the SST k-ω model, the standard k-ε model, and the Spalart–Allmaras model. The surface pressure distributions on the truck geometry and the overall drag are predicted from the simulations and compared with the experimental data. The computational predictions compared well with the experimental data. This study contributes a new validation data set and computations for high Reynolds number bluff-body flows. The validation data set can be used for initial assessment in evaluating RANS models, which will be used for studying the drag or drag trends predicted by the baseline truck geometries.

A wind tunnel study of the influence of pore water on aeolian sediment transport

Experiments conducted in a straight-line suction wind tunnel confirm numerous field observations of sand particles from an upwind source saltating over wet surfaces. Comparison of the mass transport rate on a wet surface (qw) with its dry surface equivalent (qd) yields a strong linear relationship (r2> 0·99) over a broad range in freestream velocity. Slope coefficients vary between 0·75 and 1·1. These results indicate that over short distances in the order of 5 m, the mass transport rate is minimally affected by the presence of pore water. However, the boundary-layer structure is substantially modified by grain saltation on a wet surface as compared to the dry condition. Inner region friction velocities associated with dry sand transport (u*d) generally exceed those for clean air (u*o), whileu*wfor mobile wet surfaces drops belowu*o. A model is proposed which relates the ratioqw/qdto several other dimensionless composite variables which address the aerodynamic drag on a wet surface relative to (1) that for an untreated surface and (2) capillary force magnitude. The product of these emulates the variation observed in the slope coefficients from the empirical regressions, thereby quantifying several of the underlying physical processes which govern transport in wet conditions.