Angle Sections Research Articles

Strengthening of RC beams with CFS angle sections: performance assessment of various anchoring solutions

Strengthening of RC beams with CFS angle sections: performance assessment of various anchoring solutions

Load-slip behaviour of single-leg bolted angle steel connections at elevated temperatures

Steel lattice transmission towers and communication towers are vital infrastructure components of power grid and telecommunication systems, respectively. They are usually located in rural or urban wildland areas and can be prone to bushfires or wildland fires in the current climate of heatwaves and droughts. However, an understanding of the resilience of steel lattice towers in fire has not received due attention. Such lattice structures are commonly made from steel angle members with bolted connections in which slippage might occur inevitably due to relatively larger size of bolt holes for erection purpose. Therefore, this paper investigates the axial load-slip behaviour of the single-leg bolted angle steel connections at elevated temperatures for the steel lattice structures. A three-dimensional finite element model is developed for the investigation by using ABAQUS software. Temperature-dependent material nonlinearities and the interaction of structural components at elevated temperatures are taken into account in the model. An effective approach of generating bolt pretension and the quasi-static analysis method using the dynamic explicit procedure are adopted for the analysis. The reliability of the developed finite element model is validated by comparing its predictions with available experimental results reported in the open literature. By using the validated finite element model, extensive parametric studies are conducted to elucidate the effects of the change in the angle section dimension, the direction of applied loading, the grade, size and number of the bolts on the load-slip responses of the connections at elevated temperatures. A simplified theoretical model in component formulation form is proposed and verified for predicting the axial load-slip curves of the single-leg bolted angle steel connections at elevated temperatures and would be applicable to advanced analysis of steel lattice structures considering joint slip.

Influence of Variable-Diameter Structure on Gas–Solid Heat Transfer in Vertical Shaft Cooler

In order to improve the heat transfer between high-temperature sinter and cooling gas in a vertical shaft cooler, a new furnace type with variable-diameter structure was proposed, and the influence of variable-diameter structure on gas–solid heat transfer in vertical-shaft cooler was studied by CFD-DEM coupling method in the current work. The results show that variable-diameter structure can increase the quantity of low-temperature sinter as well as the outlet cooling gas temperature, and can improve the uniformity of sinter and cooling gas temperature along the width, at the cost of significantly increasing the cooling gas pressure. By changing the parameters of the variable-diameter structure, it was found that a smaller width of the vertical section or a larger angle of the contraction section led to a better sinter–gas heat transfer. The influence of vertical section width on cooling gas pressure was more obvious. It is suggested that when designing and using the vertical shaft cooler with variable-diameter structure, consideration should be given to the effect of sinter–gas heat exchange and the pressure of cooling gas. Furthermore, the occurrence of material blockage and excessive equipment height should be avoided.

Justification principles of movement stabilization of an articulated electric bus with a rear pushing section

Introduction (statement of the problem and relevance). Currently, the need for intra-city passenger transportation is becoming more acute. High-capacity and electric buses, including articulated and double-decker ones, have proven their efficiency both in Russia and abroad and are widespread. The fact is especially important for the cities that do not have a network of high-speed transport. As a result, in these cities the passenger traffic load falls on ground transport, the main type of which is a bus or an electric bus.The purpose of the study was to increase the stability of an articulated electric bus with a rear pushing section in motion introducing an elastic-damping connection in the articulation unit.Methodology and research methods. Simulation modeling methods were used.Scientific novelty and results. It was shown that the stable movement of an articulated electric bus with a rear driving axle could be ensured by introducing an elastic-damping connection in the coupling device. The damping coefficient must be variable and dependent on the folding sections angle of the electric bus. A hydraulic system scheme for an electric bus coupling was proposed, consisting of two hydraulic cylinders, a hydraulic accumulator and spool devices, which ensured the creation of an elastic-damping connection between the sections. The differential equations analysis of the front section motion showed that its rectilinear motion was unstable. To ensure the stability of its movement in the electric bus articulation, it was necessary to create an elastic restoring moment directed against the folding sections angle. Curvilinear movement of the rear section was stable.Practical significance. It has been established that the introduction of variable throttling in the sections folding system of an articulated electric bus with a rear pushing section increases the stability of its movement when making a “turn” maneuver on supporting surfaces with low grip properties.

Research Paper on Analysis and Design of Steel Truss by using Angle and Tube Section

Now a days many structures such as railway station roof, aircraft hangers, airport terminals, parking garage, industrial building roof, large factory roof, multi-story roof truss, parking garages roof truss are for the best truss section which will suited for that selected steel roof truss structures because of the large spacing required heavy concreting and large quantity of steel for beam, column and slab casting so that is why, it is uneconomical and deflection in member is more. That’s why most probable solution for this condition tubular steel truss is unique solution within the economical point of view and various parameter are high in strength to weight ratio, low maintenance cost, long life span, no angularity, easy to manufacture and install. In today’s construction industry most of the steel building are constructed with critical sections of steel which is analysis and designed also built by regular practices approaches, therefore result of such structures are under in heavy loads or highly expensive structures. So tubular trusses are the most effective and best possible replacement for regular steel angle section. As we compare various section it is best construction industry as one of the types of steel section is most light weigh, with less economy, and other technical parameters. For low-cost economy point of view which is the main objective of the research work includes comparison of regular steel angle section structures with tube section structure for selected steel roof truss conditions. After reading literature review it is found that 15-20% cost is saved by using tube section. Analysis and design of steel roof truss elements was carried out by STADD PRO V8i computer software, by manually applying Indian Standards codes of practices. The advantage of tube section buildings is under the economy of roof truss design. There are totally different ten types of the steel roof truss section available in market. As we comparing two of them which are angle and tubular section. Other are I- section, T-section, Channel Section, Round bars, square bars, Corrugated Sheet, expanded metals, Flat sheets. This research study is carried out to provides in comparing that which method is low in economy, more load capacity of load transport of roof to purlins and purlins to members then member to column and further column to RCC block then RCC block to soil subgrade. Comparing both the section on the economical parameters by STAAD PRO V8i Software by calculating steel take off and price comparison of both the section. Also comparing parameters like node displacement, node reaction, beam reaction, min. & max axial forces and beam stresses. Structural analysis and design of both section by STADD PRO V8i computer software. After reviewing literature review papers final research paper is based on optimum and accurate steel roof truss design. Manually calculate dead load, dead load and wind load by using Indian Standard Code of Practice IS 800:2007 and IS 875(Part 3)-1987. The STAAD PRO OUTPUT method is used for determining the quantity of steel (weight) & other parameter like max. vertical displacement, max. & min. vertical force, moment at X-axis, moment at Z- axis. After analyzing fully deciding and comparing least value of quantity of steel take off in software considered as most economical truss. Key Words: Structural Analysis, Conventional/Traditional Steel Truss, Angle Section, Tube Section, AutoCAD, STAAD PRO V8i, Steel Roof Truss, IS 800: 2007, IS 806: 1968, IS 875 : 1987 for Tube Section, etc.

Critical Stress Determination of Local and Distortional Buckling of Lipped Angle Columns under Axial Compression

In recent years, cold-formed steel has been widely used in prefabricated steel structures, and the common cross-section forms are mainly complex lipped angle sections. However, there is a lack of design guidance for such a cross-section due to the complex geometric property. The restraint between adjacent plates cannot be considered proper for the traditional analytical method. Therefore, it is particularly important to study the stability bearing capacity of angle sections with complex edges under axial compression. In this paper, the finite strip software (CUFSM5) was used to analyze the critical stress of 1296 different angle sections under axial compression. The deformation diagram and the critical stress of elastic buckling were obtained. Considering the restraint between adjacent plates, the formula for predicting the critical stress of elastic local buckling of complex lipped angle sections was proposed and verified. Further, the critical stress of elastic distortional buckling of 918 complex lipped angle sections was analyzed by CUFSM. It was found that the cross-sections can be divided into two categories: cross-section without distortional point and cross-section with distortional point. It was found that the critical stress of elastic local buckling of the angle steel section can be significantly improved by the complex edge. Additionally, the critical stress of elastic local buckling of the section is less affected by the edge size for the complex edge section. The accuracy of the Hancock method for calculating the critical stress of elastic distortional buckling of complex lipped angle sections with distortional points was verified. The presented research can provide useful guidelines for designing cold-formed steel angle columns.

Comparison of Energy Performance of Shaft Tubular Pump Device at Two Guide Vane Inlet Angles

In order to improve the pump device efficiency of the frequent operating condition of the extra-low head pumping station, the energy performance of the front-positioned shaft tubular pump device at two guide vane inlet angles has been researched. Based on the function of the guide vane in the pump device, the guide vane blades are divided into three parts: the inlet section, the middle section, and the outlet section. Combining numerical simulation and model tests, the energy performance of the pump device with the inlet section angle adjusted to 0° and −12° were studied and compared, respectively. The research results indicate that the inlet section angle of the guide vane has a significant effect on the energy performance of the pump device. When the guide vane inlet section is adjusted clockwise, the pump device efficiency of the optimal operating point—while the efficiency of the pump device at a low head and large discharge that deviate from the optimal operating point—will be improved. The farther the working condition deviates from the optimal operating point, the greater the influence. Within the scope of the working conditions studied in this paper, the pump device efficiency of the optimal operating point is reduced by about 2%, and the pump device efficiency in the low head and high flow conditions is increased by 5% at the maximum. Adjusting the inlet section angle of the guide vane, the flow pattern in the guide vane will be improved, and the hydraulic loss of the guide vane will be decreased, thus the pump device efficiency is increased. The numerical calculation results of the energy performance agree with the model test results; the maximum error of the pump device efficiency is less than 7%. Adjusting the angle of the inlet section of the guide vane has great significance to the hydraulic design and engineering application of the extra-low head pump device.

Joint Slip Formulation for Members with Double Angle Section Based on Experimental Results in Wind Turbine Lattice Towers

Joint Slip Formulation for Members with Double Angle Section Based on Experimental Results in Wind Turbine Lattice Towers

Morphological Analysis of Hip Joint of Patients Suffering From Recurrent Patella Dislocation.

The purpose was to investigate morphological changes of the hip joint in patients with recurrent dislocation of the patella combined with trochlear dysplasia. There was a retrospective analysis of 148 patients and 150 control subjects. The selection of participants was randomized. Hip and knee data for all participants were obtained from X-ray or computed tomography measurements. Nine values, that is, central edge angle (CEA), acetabulum index angle (AIA), femoral neck-shaft angle, sharp angle, the depth of the acetabulum, femoral anteversion angle (FAA), anterior acetabular section angle (AASA), posterior acetabular section angle (PASA), and sulcus angle, were measured to evaluate differences between the control group and the patient group and analyze the correlation of the sulcus angle in patients to FAA and CEA. Patients with recurrent dislocation of the patella had less acetabular coverage and are more likely to develop developmental dysplasia of the hip than the hips of patients with normal knees. For the patient group, three values, that is, CEA (27.68 ± 5.25 vs. 34.30 ± 3.51 degrees, p < 0.001), AASA (57.14 ± 6.17 vs. 63.08 ± 7.23 degrees, p < 0.001), and PASA (89.53 ± 6.51 vs. 99.63 ± 5.94 degrees, p < 0.001), were decreased. The sharp angle (43.77 ± 3.23 vs. 39.28 ± 3.19 degrees, p < 0.001), AIA (11.52 ± 4.41 vs. 3.73 ± 2.51 degrees, p < 0.001), and FAA (24.68 ± 3.44 vs. 18.49 ± 3.55 degrees, p < 0.001) were increased. The acetabulum became shallower in-depth (7.05 ± 2.18 vs. 10.45 ± 1.61 mm, p < 0.001). There was a weak correlation between the sulcus angle and CEA (r = - 0.302, p < 0.001) and FAA (r = 0.212, p = 0.022). Recurrent patellar dislocation combined with trochlear dysplasia may be associated with the hip morphology. Developmental disorders of the knee joint, and hip joint should be considered in the treatment of patients with recurrent dislocation of the patella.

Cold-Formed Steel Equal Angles with Complex Edge Stiffeners under Axial-Compression Laboratory Testing, Numerical Simulation, and Design

This paper investigates the axial-compression capacity of cold-formed steel (CFS) equal angle sections with complex edge stiffeners. Both experimental and numerical analyses were carried out. In total, 10 tests were carried out and the results are presented in this paper. Preceding to compression tests, the material properties were determined and initial geometric imperfections of all the test specimens were measured. From the results of compression tests, the specimens were all susceptible to flexural buckling. A numerical model was created using the finite-element (FE) software ABAQUS version 6.11. The results of finite-element analysis (FEA) substantiated with the experimental results. The FE models were found to accurately predict the experimental behavior. Thus, the validated FE models were used for a parametric study to analyze the effect of slenderness ratio and the orientation of edge stiffeners on the axial capacity. The axial strengths obtained from parametric study were compared with the design strengths calculated by the direct strength method (DSM) from the American Iron and Steel Institute (AISI) specification. Upon comparison, it was found that the axial strengths calculated based on the current DSM are overconservative by 58% on an average.

Jacketing with steel angle sections and wide battens of RC column and its influence on blast performance

Jacketing with steel angle sections and wide battens of RC column and its influence on blast performance

What Factors Are Associated With Postoperative Ischiofemoral Impingement After Bernese Periacetabular Osteotomy in Developmental Dysplasia of the Hip?

Any abnormal structures that contribute to the narrowing of the ischiofemoral space could induce ischiofemoral impingement. Bernese periacetabular osteotomy (PAO) medializes the hip center and, therefore, decreases contact stress on the cartilage in developmental dysplasia of the hip (DDH). However, medialization of the hip center might also narrow the ischiofemoral space, which may increase the risk of postoperative ischiofemoral impingement in patients with acetabular dysplasia who are undergoing PAO. Furthermore, the dysplastic hip has less ischiofemoral space and less space for the quadratus femoris. A few studies have focused on the amount of medialization of the hip center, but the proportion of postoperative ischiofemoral impingement after PAO has not been investigated. (1) What proportion of patients develop ischiofemoral impingement after undergoing unilateral PAO for DDH? (2) What radiographic factors are associated with postoperative ischiofemoral impingement in patients who underwent PAO for DDH? (3) How much hip center medialization is safe so as to avoid postoperative ischiofemoral impingement during PAO? Between 2014 and 2016, we treated 265 adult patients who had symptomatic residual acetabular dysplasia (lateral center-edge angle less than 20°) using PAO. During that time, we generally offered PAO to patients with acetabular dysplasia when the patients had no advanced osteoarthritis (Tönnis grade < 2). Of those, we considered only patients who underwent primary PAO without femoral osteotomy as potentially eligible. Based on that, 65% (173 of 265) were eligible; a further 9% (24 of 265) were excluded due to leg length discrepancy, spine disorders, or joint replacement in the contralateral side, and another 6% (17 of 265) of patients were lost before the minimum study follow-up of 2 years or had incomplete datasets, leaving 50% (132 of 265) for analysis in this retrospective study at a mean of 2.70 ± 0.71 years. The diagnosis of ischiofemoral impingement was defined by symptoms, MRI, and diagnostic ischiofemoral injection. We ascertained the percentage of patients with this diagnosis to answer the first research question. To answer the second question, we divided the patients into two groups: PAO patients with ischiofemoral impingement and PAO patients without ischiofemoral impingement. The demographic data and preoperative imaging parameters of patients in both groups were compared. There were statistical differences in acetabular version, ischial angle, neck-shaft angle, the presence of positive coxa profunda sign, McKibbin index, ischiofemoral space, quadratus femoris space, anterior acetabular section angle, and the net amount of hip center medialization. To investigate potential factors associated with postoperative ischiofemoral impingement in patients who underwent PAO, these factors underwent binary logistic regression analysis. To answer the third question, the cutoff value of the net amount of hip center medialization was evaluated using receiver operator characteristic curve and the Youden index method. We found that 26% (35 of 132) of PAO dysplastic hips had postoperative ischiofemoral impingement. After controlling for confounding variables such as acetabular version, ischial angle, femoral neck version, McKibbin index, and ischiofemoral space, we found that an increasing neck-shaft angle (odds ratio 1.14 [95% confidence interval 1.01 to 1.29]; p = 0.03), a positive coxa profunda sign (OR 0.13 [95% CI 0.03 to 0.58]; p < 0.01), and an increasing net amount of hip center medialization (OR 2.76 [95% CI 1.70 to 4.47]; p < 0.01) were associated with postoperative ischiofemoral impingement in patients with DDH who underwent PAO (R 2 = 0.73). The cutoff values of neck-shaft angle was 138.4°. The cutoff values of the net amount of hip center medialization was 1.9 mm. Postoperative ischiofemoral impingement could occur in patients with acetabular dysplasia who have undergone PAO after hip center medialization. An increasing neck-shaft angle, a positive coxa profunda sign on preoperative imaging, and excessive medialization of the hip center are factors associated with ischiofemoral impingement development in these patients. Therefore, we suggest that physicians measure the ischiofemoral space on a preoperative CT when patients with DDH have an increasing neck-shaft angle (> 138.4°) or a positive coxa profunda sign on radiological imaging. During PAO, the amount of hip center medialization should be carefully controlled to keep these patients from developing postoperative ischiofemoral impingement. Level III, therapeutic study.

Research on seriation design of Dynamic Kill Drilling (DKD) mixer

Abstract Automatic slurry mixing device, one of the core equipment of dynamic kill drilling (DKD) system, is the key to determine whether the drilling fluid system can provide precise density for bottom layer in time and effectively, and also the key equipment to control the operation risk of ultra-deep water drilling in the face of narrow pressure window. Based on the incompressible viscous flow characteristics of non-Newtonian fluid mixed with seawater and combined with the actual drilling fluid field situation of offshore drilling platform, a kind of tubular DKD mixer with dumbbell shaped nozzle as jet element is designed in this paper, which is verified by theoretical calculation and numerical simulation. Finally, “Y type reverse reflux (60°) + 90° cross jet element” was determined as the final structural design scheme. At the same time, the influences of inlet flow rate, length of eddy current section and incident Angle on mixing effect of mixer are studied, and a seriation design scheme of dynamic kill drilling (DKD) mixer is proposed, and a seriation design chart of product is completed.

Experimental and numerical study on dynamic response of concrete filled steel tubular pile subjected to oblique impact

To study the dynamic performance of concrete-filled steel tubular (CFST) piles under impact loads, the strain and displacement responses of the members were studied by oblique impact tests. Then the experimental process was simulated, and the simulation results are in good agreement with the test. Finally, parameter analysis based on numerical simulation is conducted to study the influence of the section stiffness and impact energy on the dynamic response of the members, as well as the energy absorption of the members are studied, and the response mode of the members is summarized. The results show that the response modes of CFST piles can be summarized as slight bruise at the impact point, dented damage at the impact point, bending deformation of the member, and failure of restrained end of the member. The displacement and energy absorption rate are sensitive to the variation of section stiffness, impact energy, impact height and angle. The impact force is sensitive to the change of section stiffness, impact energy and height, but not sensitive to the change of impact angle. The energy absorption rates are more than 50%, and the maximum energy dissipation rate reaches 91.3%.

Wide Bandwidth Wind-Induced Vibration Energy Harvester with an Angle Section Head

A high-performance wind-induced vibration energy harvester with an angle section head is designed. Experimental results show that the harvester has a wide frequency-locked/operating wind speed range. Experiments are carried out for the harvester with different angles and lengths of the angle section head. It is found that the reasonable design of the angle section head can benefit wind energy harvesting. In this study, the widest operating wind speed range of 13.4 m/s (from 6.6 m/s to 20 m/s) is experimentally demonstrated, and the maximum output power is 214.6 μW.

Experimental and numerical studies of stainless steel angle-to-plate connections

This paper presents experimental and numerical studies of stainless steel angle-to-plate connections failing by net section fracture. Tension tests were conducted on 16 austenitic stainless steel angle-to-plate connections, with each consisting of an equal-leg or unequal-leg angle section member bolted to gusset plates by one leg. The specimens were designed with different angle section sizes, number of bolt holes and connection lengths. The key test observed results, including the load–elongation curves as well as the failure loads and modes, were fully reported. The strain distribution at critical cross-sections and the effects of connection length, out-of-plane eccentricity and in-plane eccentricity on net section efficiency were discussed. The experimental programme was supplemented by a numerical modelling programme, where finite element models were firstly developed and validated against the test results and afterwards adopted to perform parametric studies to generate further numerical data. On the basis of the test and numerical data, the accuracy of the design rules for stainless steel angle-to-plate connections failing by net section fracture, as set out in the European code and American specification, was assessed. The assessment results revealed that the European code leads to excessively conservative and scattered failure load predictions, while the American specification yields unsafe failure load predictions. Therefore, an improved design approach was proposed and shown to provide substantially improved predictions of failure load over the design codes; the reliability of the proposed design approach was also demonstrated by statistical analyses. Besides, the existing codified and proposed design methods for carbon steel angle-to-plate connections were also assessed for their applicability to stainless steel angle-to-plate connections. It was found that the method specified in the American specification for carbon steel angle-to-plate​ connections can be safely extended to cover the design of their stainless steel counterparts.

Testing, numerical analysis and design of stainless steel equal-leg angle section beams

The stability and design of stainless steel equal-leg angle section members subjected to uniaxial bending are studied herein. An experimental investigation, comprising material testing, initial geometric imperfection measurements and physical tests on hot-rolled austenitic stainless steel equal-leg angle section beams is first presented. The test results are then used to validate shell finite element models developed within ABAQUS, which are in turn used to undertake numerical parametric studies that consider both hot-rolled and cold-formed equal-leg angle section beams in austenitic, duplex and ferritic stainless steel with a wide range of slenderness values. Recent studies have shown that for angles under major-axis bending, both lateral-torsional and local buckling can arise, while under minor-axis bending, lateral-torsional buckling and Brazier-type flattening can occur. When designing for major-axis bending according to Eurocode 3, both local and lateral-torsional buckling are considered; it is shown herein that equal-leg angle sections under major-axis bending can be designed using a normalised slenderness based on the minimum of the local and lateral-torsional elastic buckling moments, while also considering their ratio. Under minor-axis bending, however, in comparison with the current provisions in Eurocode 3 that only require cross-section checks, it is shown that both safer and more accurate resistance predictions can be achieved when account is taken for lateral-torsional buckling and Brazier-type flattening. New design proposals for stainless steel equal-leg angle section beams, covering both major- and minor-axis bending, are therefore developed. The proposed design rules offer substantially more accurate and consistent resistance predictions compared to existing codified design rules. The reliability of the new design provisions, with a recommended partial safety factor γM1=1.1, is verified following the procedure provided in EN 1990.

Limit Carrying Capacity Calculation of Two-Way Slabs with Three Simply Supported Edges and One Clamped Edge under Fire

Fire-resistance experiments were conducted on two full-scale two-way reinforced concrete slabs with three simply supported edges and one clamped edge. This paper presents the design of the furnace, specimens and clamped-end device, the test plan, and the measuring contents and methods. The cracking and failure characteristics of the tested two-way reinforced concrete slabs were introduced. The temperature field distribution of the concrete and steel in the direction of the section thickness, out-of-plane deflections, in-plane deflections, and angle of the slab edges of the two-way concrete slab under fire conditions were analyzed. Cracks form on the slab surface, which is shaped similar to the bottom of a shallow bowl, with two transverse cracks in the mid-area of the medially clamped side and intensively annular diagonal cracks on the corner side. There were several main transverse cracks in the central area of the slab surface. The results indicate that there was a significant decrease in frequency under fire conditions. Relations between the frequency and the central vertical deflection of the two slabs were analyzed by the regression method. This research generates valuable test data that can be used to validate the numerical models developed by fellow researchers in the field of structural fire engineering. Based on the plate balance method and energy method, calculation formula of the limit carrying capacity calculation formula of reinforced concrete two-way slabs with four different boundaries under fire are given, which are simply supported on three sides and clamped on one side. The influence of membrane effect under large deflection is considered in the formula, and the calculated results are in good agreement with the experimental results.

Compression tests on large angle columns in high‐strength steel

AbstractNominated for Eurosteel 2021 Best Paper AwardThe paper addresses the instability of large angle columns in high‐strength steel subjected to compression loads. It presents a number of compression tests on such columns with different eccentricities and slenderness and the resulting different buckling failure modes observed. The experimental campaign is intended to widen our understanding of the behaviour of high‐strength steel columns with large angle sections in compression and bending and so to complement previous experimental studies. The tests were accompanied by numerical analyses and calculations of the load carrying capacities based on current Eurocode 3 design recommendations. The numerical simulations were conducted using the FEM software FINELG, which takes into account the influence of geometrical and material non‐linearities. The numerical and analytical results are compared with the corresponding experimental ones. The experimental campaign and the numerical simulations were conducted as part of the ANGELHY project funded by the European Commission's Research Fund for Coal and Steel (RFCS).

Numerical and experimental study of the ducted diffuser effect on improving the aerodynamic performance of a micro horizontal axis wind turbine

In the present study, the impact of utilizing an encompassing duct on the aerodynamic performance of a micro horizontal axis wind turbine (HAWT) was numerically and experimentally studied. A duct comprised of a diffuser and a flange was designed and constructed. A wind simulator facility and a micro scale wind turbine were employed to conduct the experimental investigations. Measurements of velocity and power output of the turbine have been carried out. The numerical results obtained at different stages of the research were validated separately and then compared with our experimental data and those obtained by other researchers. Consequently, the numerical predictions match well with the experimental measurements. In the first part of the study, fluid flow through the empty duct was analyzed. Then, by adding a nozzle at the diffuser entrance of the original duct, an improved design was proposed and numerically modeled to achieve higher wind speed at the throat position of the duct. The modified design was further enhanced by altering the converging and diverging section's angles (ranging from 0 to 90° with the angle increment step of 5°). Fifty-two different duct configurations have been considered to achieve the optimal angles of the nozzle, the diffuser, and the flange. Moreover, the aerodynamic performance of the micro HAWT was studied in three different conditions: without a duct, with the original duct, and with the improved duct. The results show that the improved duct increases the inlet wind speed from 5 m/s to 10.7 m/s (i.e., up to 2.14 times) at the throat position, which increases the wind speed up to 47% compared to the original duct. Furthermore, the power coefficient of the turbine increases from 0.33 to 1.2 (i.e., up to 3.64 times) in comparison to the case without duct, which increases by about 164% compared to the original duct. Also, employing the improved duct design causes a lower level of flow turbulence kinetic energy compared to the original duct design. This valuable outcome reduces the noise level generated by the system and the dynamics forced exerted by the rotor to other possible downstream structures.