Taper Ratio Research Articles

Wing Planform Analysis with Taper Ratio and Expansion Segment Variation with Lifting Line Theory

Tapered wing shape of a planform wing is still widely used amongst airplane and UAVs with subsonic speed. In the design process, a good consideration for a good taper ratio of a wing is required to obtain the optimal and distribution for the desired function of an aircraft. Additionally, addition of expansion segment on wing planform shape is often used to increase the performance of wings without the increase of wingspan. Several methods to analyze a wing shape are experimentation, computational luid dynamics, and analytical calculation. Analyzing with analytical calculation will present limited, but accurate outcomes due to the assumptions that are made during the calculation. This method, however, is inexpensive. This is why analytical calculation is still a common method to use in the design process of an aircraft, particularly in the early phase. Five variants of taper ratio and 3 variants that with expansion segment is analyzed using the Lifting Line Theory that utilizes Fourier series at subsonic speed. The results are the values of and with respect to and the distribution of and along the wingspan. Increasing the taper ratio results in the decrease of and the increase of , while adding an expansion segment will give results that are dependent on the added segment’s taper ratio.

Laminar post-stall wakes of tapered swept wings

While tapered swept wings are widely used, the influence of taper on their post-stall wake characteristics remains largely unexplored. To address this issue, we conduct an extensive study using direct numerical simulations to characterize the wing taper and sweep effects on laminar separated wakes. We analyse flows behind NACA 0015 cross-sectional profile wings at post-stall angles of attack $\alpha =14^\circ$ – $22^\circ$ with taper ratios $\lambda =0.27$ – $1$ , leading-edge sweep angles $0^\circ$ – $50^\circ$ and semi aspect ratios $sAR =1$ and $2$ at a mean-chord-based Reynolds number of $600$ . Tapered wings have smaller tip chord length, which generates a weaker tip vortex, and attenuates inboard downwash. This results in the development of unsteadiness over a large portion of the wingspan at high angles of attack. For tapered wings with backward-swept leading edges, unsteadiness emerges near the wing tip. On the other hand, wings with forward-swept trailing edges are shown to concentrate wake-shedding structures near the wing root. For highly swept untapered wings, the wake is steady, while unsteady shedding vortices appear near the tip for tapered wings with high leading-edge sweep angles. For such wings, larger wake oscillations emerge near the root as the taper ratio decreases. While the combination of taper and sweep increases flow unsteadiness, we find that tapered swept wings have more enhanced aerodynamic performance than untapered and unswept wings, exhibiting higher time-averaged lift and lift-to-drag ratio. The current findings shed light on the fundamental aspects of flow separation over tapered wings in the absence of turbulent flow effects.

Study on seismic performance of tapered castellated steel member portal frame

Low-cycle reciprocating loading test is applied to a tapered castellated steel member portal frame to study its seismic performance. Moreover, 52 finite element models are utilized to analyze the effects of the opening ratio of the beam web, the opening ratio of the column web, and the taper ratio of the beam on the failure mode, hysteresis curves, ductility, and energy-dissipating capacity of tapered castellated steel member portal frame. The results show that tapered castellated steel member portal frame can realize the failure mode of the plastic hinge at the beam end. The ductility coefficient of the specimen is between 4.78 and 5.49, and the maximum equivalent viscous damping coefficient is 0.146, indicating that the structure offers good ductility and energy-dissipating capacity. When the opening ratio of the castellated beam web is 60–70%, and the taper ratio of the castellated beam is less than 1.4, the structure exhibits good seismic performance. As castellated beams and columns have different stiffness values due to different web opening ratios, this study proposes an equivalent beam–column linear stiffness ratio to satisfy the seismic performance design requirement of “strong columns and weak beams” for tapered castellated steel member portal frame. A method is also devised to calculate the equivalent stiffness of tapered castellated members. Comparing the predictions of this method with experimental results reveals that its maximum error is 7.66%, indicating its high precision. It is recommended that the equivalent beam–column linear stiffness ratio of tapered castellated beam–column portal frames should be higher than 2.735. On this basis, an opening ratio of the castellated column web ranging from 50% to 70% has a negligible effect on the seismic performance of the structure.

Effect of taper ratio on 2-D mechanical wind sensors

In this paper, the effect of sensing-structure taper ratio on two-dimensional (2-D) mechanical wind sensors is demonstrated for the first time. The mechanical wind sensor consists of a sensing structure vertically arranged in the center of a cross cantilever. It detects the wind speed and direction by measuring the airflow-induced cantilever deformation with eight strain gauges attached to the beam surface. Five forms of sensing structures with different taper ratios are designed and manufactured to investigate their effects on the performance of 2-D mechanical wind sensors. A series of experiments are conducted and the results reveal that the taper ratio of the sensing structure can affect the measurement range and the sensitivity of the 2-D mechanical wind sensor. A lower taper ratio results in a higher critical wind speed, which makes the mechanical wind sensor a wider measurement range. Moreover, the results also show that a wider measurement range usually means a lower sensitivity for a single device, and hence the measurement range and the sensitivity of the mechanical wind sensor are a contradiction. The effect rule of the taper ratio presented in this paper can provide a valuable reference for the design and manufacture of 2-D mechanical wind sensors.

Nanoparticle Incorporation to Enhance Titanium Alloy Electric Discharge Machining Capabilities

The primary objective of this study was to examine the effects of the Powder-blended Micro Electric Discharge Machining (PMEDM) technique on micromachining applications, specifically when sea water is employed as the dielectric medium. Tiny apertures with a width of 200µm were punctured over Ti-6Al-4V plates. In the initial round of experimentation, the machining performance was evaluated by subjecting sea water to various process variables without the inclusion of any other ingredients. The effects of input variables, including electrode material, hole voltage, current, Pulse-on-time, and Duty factor, on the Material Removal Rate (MRR), Tool Wear Rate (TWR), Overcut (OC), Circularity Error (CE), and Taper Ratio (TR) were analysed by conducting tests in accordance with Taguchi's L18 plan design. The method employed to ascertain the optimal parametric configuration for multi-objective enhancement involved utilising the strategy of soliciting inclination based on similarity to an ideal arrangement. The present study aimed to investigate the effects of foreign materials on the dielectric-based miniature electrical discharge machining (EDM) process in sea water. This was achieved by utilising powders with varying weight concentrations and molecule sizes, including non-conductive (Al2O3), semi-conductive (SiC), and conductive (Al) powders. The experimental setup ensured that the variable boundaries were maintained at their ideal settings. The results indicate that the choice of tool has a notable influence on the functioning of micro EDM when sea water is employed as the dielectric, without the inclusion of extraneous particles. The performance metric of multi-objective execution in PMEDM is influenced by the conductivity of supplementary compounds. An 83.18 percent increase in Material Removal Rate (MRR) was observed when SiC added compounds were utilised in Powder Mixed Electrical Discharge Machining (PMEDM). Conversely, there was a drop in Tool Wear Rate (TWR) by 36.42 percent, Open Circuit voltage (OC) by 21.48 percent, Current Efficiency (CE) by 45.15 percent, and Tool Roughness (TR) by 22.87 percent.

Dynamics of Spinning Viscoelastic Tapered Shafts with Axial Motion

In this paper, the vibration and stability of spinning viscoelastic tapered shafts with axial motion are investigated. The model of the shaft system is developed by incorporating the spinning motion, axial motion, axial load, viscoelasticity, and geometric properties. The coupled governing equations of motion of the spinning shaft system are obtained by applying Hamilton’s principle. By employing the Laplace transform and Galerkin discretization method, the natural frequency and modal damping are computed. Also, the critical divergence axial and spinning velocities, as well as the flutter axial velocity, are determined. As a result, the divergence and flutter instability conditions of the system are examined. The effects of the main parameters, such as taper ratio, axial load, and viscoelasticity of material, on the vibration behavior of the shaft system are evaluated. The results show that compared to the homogeneous spinning shaft system with uniform cross-section, the vibration and stability of the viscoelastic tapered shaft system undergo an essential evolution. It is further demonstrated that the axial load and viscoelasticity are also the key parameters governing the stability of the system.

Buckling Resistance of Tapered Steel Columns

Tapered steel members are widely used in structural and architectural engineering for their efficiency and adaptability, allowing for optimal material usage tailored to specific load levels. However, their complex stability characteristics have hindered their representation in modern design standards like EN 1993 and AISC 360. Existing buckling solutions are limited, and practical research is lacking. This paper comprehensively examines the buckling resistance calculation methodologies for members with variable cross-sections, addressing discrepancies across the methodologies, particularly regarding the tapering ratio. A parametric analysis and numerical simulations were conducted to evaluate each methodology’s applicability, emphasizing the need to balance computational simplicity and accuracy. The study primarily focused on tapered steel beams, considering the different tapering ratios and loading conditions. The findings provide valuable insights into the buckling behavior in tapered members and the practical implications for real-world structural designs. By examining the available analytical methods for calculating the buckling resistance of tapered elements, a better understanding of how to accommodate the non-uniformity of a member was gained, enabling an overview of the variance in the determined resistances and an assessment of the method’s applicability. Moreover, specific calculation methodologies were found to have shortcomings that require modifications for a more accurate parametric analysis. This research contributes to the field by bridging the gaps in modern design standards and enhancing the understanding of buckling in tapered steel members.

Comparative study on free vibration analysis of rotating bi-directional functionally graded beams using multiple beam theories with uncertainty considerations

The present study investigates the free vibration behavior of rotating beams made of functionally graded materials (FGMs) with a tapered geometry. The material properties of the beams are characterized by an exponential distribution model. The stiffness and mass matrices of the beams are derived using the principle of virtual energy. These matrices are then evaluated using three different beam theories: Bernoulli–Euler (BE) or Classical Beam Theory (CBT), Timoshenko (T) or First-order Shear Deformation Theory (FSDT), and Reddy (R) or Third-order Shear Deformation Theory (TSDT). Additionally, the study incorporates uncertainties in the model parameters, including rotational velocity, beam material properties, and material distribution. The mean-centered second-order perturbation method is employed to account for the randomness of these properties. To ensure the robustness and accuracy of the probabilistic framework, numerical examples are presented, and the results are compared with those obtained through the Monte Carlo simulation technique. The investigation explores the impact of critical parameters, including material distribution, taper ratios, aspect ratio, hub radius, and rotational speed, on the natural frequencies of the beams is explored within the scope of this investigation. The outcomes are compared not only with previously published research findings but also with the results of 3-Dimensional Finite Element (3D-FE) simulations conducted using ANSYS to validate the model’s effectiveness. The comparisons demonstrate a strong agreement across all evaluations. Specifically, it is observed that for thick beams, the results obtained from FSDT and TSDT exhibit a greater agreement with the 3D-FE simulations compared to CBT. It is shown that the coefficient of variation (C.O.V.) of first mode eigenvalue of TSDT, FSDT and CBT are approximately identical for random rotational velocity and discernible deviations are noted in CBT compared to FSDT and TSDT in the case of random material properties. The findings suggest that TSDT outperforms FSDT by eliminating the need for a shear correction coefficient, thereby establishing its superiority in accurately predicting the natural frequencies of rotating, tapered beams composed of FGMs.

CFD simulation of wind loads of kilometer‐scale super tall buildings with typical configurations in veering wind field

SummaryThe atmospheric boundary layer (ABL), whose total height is about 1–1.5 km, is composed of the atmospheric surface layer (ASL) and the Ekman layer, which typically account for the lower 10% and the upper 90% of the ABL, respectively. The wind veering angle in the Ekman layer can be between 10° and 30°, which may be an important influence factor for the wind‐resistant design of kilometer‐scale super‐tall buildings. Unfortunately, there is very little research on this issue so far due to the difficulty in simulations of veering wind in wind tunnels and computational fluid dynamics (CFD) simulation platforms. In this study, the simulations of non‐veering and veering wind fields are presented, and furthermore, the wind loads of kilometer‐scale super tall buildings with several typical configurations in veering wind fields are numerically investigated. Specifically, the large eddy simulations (LES) of unsteady flow around three buildings, namely, a square building, a tapered building (tapering ratio: 6.6%), and a 4‐layer setback building with the same height and the same aspect ratio of 9:1, are systematically performed for the cases of veering wind and non‐veering wind. The wind pressures and wind forces on these buildings are obtained and comprehensively analyzed. The differences in the wind loads among the building configurations are highlighted, and the mechanisms are discussed based on the time‐averaged and instantaneous flow fields.

Nonlinear dynamic analysis of anisotropic bimorph dielectric elastomer actuator for soft fish robots

Electric fields when applied to smart materials like dielectric elastomers (useful for biomimetic creatures), provide a greater amount of mechanical actuation, but concerns with various drawbacks of isotropic dielectric elastomers whereas by imparting anisotropy through reinforcing soft fibers in such materials is used to overcome the drawbacks associated with it. Thus, in this study, nonlinear dynamic analysis of anisotropic visco-hyperelastic convex tapered bimorph dielectric elastomer actuator is reported to mimic actual fish tail by providing flaps through actuation. Experimental stress relaxations of the elastomer at different temperatures are performed using dynamic mechanical analysis (DMA 8000) to determine shear moduli (relaxed and unrelaxed) and relaxation time. The thermo-electro-visco-hyperelastic behavior of such actuators is represented by the Gent model of hyperelasticity in conjunction with the new relaxation model of viscoelasticity based on the obtained experimental data. Thereby, the governing equation of motion is derived based on Euler Lagrangian principle and solved through MATLAB and Simulink to analyze the nonlinear dynamics of active layer for such anisotropic actuators. For this present analysis, the fiber angles of the reinforcement, the taper ratio, and the temperatures are altered to study the effects of these parameters on the time series and frequency responses. The frequency spectrum shows generation of different frequencies which are linear combination of natural and excitation frequencies. The stretch histories, deflections, phase planes, Poincaré maps along with hysteresis loops and bifurcation diagram are attained to represent the physical behavior of nonlinear dynamics. Then from the responses it is inferred that with an increase in temperature and taper ratio, the stretch and deflection also increases, since the natural frequency and stiffness decreases for particular fiber angle. From the phase portraits, the quasi-periodic nature of the system is evident at dominant spike and the hysteresis loop indicates energy dissipation. From the bifurcation diagram analysis, sub or super of the dominant amplitude of frequency exists. At low frequency it is found that the stretch histories are chaotic.

Thermoelastic free vibration analysis of functionally graded conical shell based on trigonometric higher-order shear deformation theory

The fundamental frequency of a rotating cantilevered porous functionally graded (FG) twisted conical shell with varying thickness along the longitudinal direction is calculated using a trigonometric higher-order shear deformation theory under thermal loading. Finite element method is employed for this purpose. The shell is discretized using eight-noded isoparametric shell elements with seven degrees of freedom per node. Using a simple power law across the transverse direction, the temperature-dependent material properties of the FG shell are determined. The nonlinear temperature distribution across the thickness direction is calculated using the one-dimensional Fourier heat conduction equation. The dynamic equation of motion is derived using Lagrange's equation. Finally, a parametric investigation of the effects of taper ratio, porosity, pretwist angle, temperature, and rotational speed on the fundamental frequency of the porous FG rotating conical shell is performed. It is also discussed how such characteristics affect mode shapes.

Structural parameters optimization of tapered fiber SPR sensor based on BES algorithm

Aimed at the numerous parameters that affect the performance of fiber Surface Plasmon Resonance (SPR) sensor, which make it difficult to determine the optimal parameters by traditional mathematical modeling, on the one hand, a tapered fiber SPR sensor model is proposed to improve the detection sensitivity of sensor. On the other hand, a new intelligence algorithm with fast search speed and high search accuracy, Bald Eagle Search Algorithm (BES), is adopted to optimize the structural parameters of tapered fiber SPR sensor, including the metal film thickness (d2), sensing area length (L), taper ratio (TR), and measured refractive index (n3). At the same time, a comprehensive fitness function is defined to improve the optimization effect, which take the sensitivity, resolution and linearity of the proposed sensor model into account. In the verification process, establish three different optimization experiments, including one partition optimization, two partition optimizations and three partition optimizations. The experimental results indicate that the optimization effect of the three partition optimizations is the best, for three different optimization intervals, the obtained fitness function values are 80%, 81% and 78%, respectively. In addition, the performance of BES is compared with other five optimization algorithms, the results indicate that the best shape of SPR reflection spectrum can be obtained by BES, its average sensitivities is 2218.85 nm/RIU, which ranks first. Therefore, by three partition optimizations and BES algorithm, the optimized parameters are more representative, which make the obtained reflection spectrum based on the optimized parameters has smallest degradation. The proposed method can provide an efficient and intelligent design idea for SPR sensor, it can greatly increase the flexibility of SPR sensor design.

Effects of taper ratio on the aerodynamic forces and flow field of two tandem square cylinders

To explore the influence of taper ratio on aerodynamic characteristics of tandem square cylinders, three-dimensional (3D) large eddy simulations of flow around two tandem square cylinders at the Reynolds number (Re) = 2 × 103 are carried out with a spacing ratio G/D = 4, where G is the cylinder center-to-center distance and D is the cylinder width. Different taper ratios of ξ = 0%, 5%, 10%, and 15% are considered. The influence of taper ratio on aerodynamic coefficient, wind pressure coefficient, mean, and instantaneous flow fields are comprehensively studied. The mechanism of variation in flow fields is revealed, and the mathematical relationship between the taper ratio and aerodynamic characteristics is established, which can provide theoretical reference for design and construction of tandem structures. The results indicate that the taper ratio has significant influence on the mean force coefficient, fluctuating force coefficient, surface mean and fluctuating pressure coefficients, and vortex shedding frequency (fvs). As increase in the taper ratio, the mean force in the along-wind direction, fluctuating force in the across-wind direction, and surface pressure of the two cylinders will be decreased, but the vortex shedding frequency will be increased. The taper ratio has negligible influence on the flow separation location of the upstream cylinder. However, reattachment location of the shear layer moves backward along the leeward surface of the downstream cylinder, and width of the shear layer gradually becomes narrower and closer to surface of the two cylinders. The vortex shedding strength and vortex energy distribution of the two cylinders will be reduced as a result of the narrower shear layer. Meanwhile, coherence and periodicity of the vortex shedding will also be weakened, which results in reduction in the aerodynamic forces and increase in the vortex shedding frequency.

Free Vibration Analysis of Elastically Restrained Tapered Beams with Concentrated Mass and Axial Force

This study proposes a new numerical method for the free vibration analysis of elastically restrained tapered Rayleigh beams with concentrated mass and axial force. The beam model had elastic support, concentrated mass at both ends, and axial force at the right end. The elastic supports were modeled as translational and rotational springs. The shear force and bending moment were determined under the assumption that the sum of the forces at arbitrary positions and the joint between the beam and elastic supports always becomes zero. Therefore, a frequency determinant is established considering the free-free end condition at both ends, but various boundary conditions were constructed by adjusting the values of the elastic springs in the frequency equation. This assumption simplified the deduction procedure, and the method’s efficiency was demonstrated through various comparisons. In particular, the value of compressive loading at which the first natural frequency vanished was investigated by considering the taper ratio based on the relationship between the elastic support and compressive loading. The analyzed results can be adopted as benchmark solutions for other approaches. The frequency determinant employs the transfer matrix method; however, numerical methods can easily be utilized in other approaches.

Experimental investigations on the vortex-shedding from a highly tapered circular cylinder in smooth flow

This paper presents the results of a wind tunnel test campaign conducted to investigate the aeroelastic and aerodynamic behaviour of a tapered circular cylinder in smooth flow conditions. The model under investigation is a single-mode aeroelastic one, whose taper ratio (in terms of diameter) is 8 %. Its global dynamic response was measured through the use of an internally-mounted piezo-electric accelerometer. The sensitivity of the vortex-induced response to different levels of structural damping was explored. The harmonic content of the wake was also measured through a hot-wire anemometer positioned downstream of the wind tunnel model at different heights: this allowed the detection of the portion of the model whose local resonance was accountable for the highest vortex-induced structural response. To further expand the findings of the wake measurements, four ‘rings’ of surface-mounted pressure sensors were installed on the wind tunnel model. The Reynolds number that was covered during the experiments ranged between 9.3×103 and 3.2×104.The experimental investigations revealed that the tapering has a beneficial effect with respect to vortex-induced oscillations, reducing their magnitudes when compared against the ones of a parallel-sided circular cylinder. On the other hand, the lock-in region was found to be wider, exhibiting three distinct peak regions for the lowest level of structural damping. The combined results from the accelerometer, the hot-wire anemometer and the pressure measurements, and the application of tailored time–frequency analyses based on the continuous wavelet transform, revealed that the maximum dynamic response is linked to the local resonance between the fundamental frequency and the bottom portion of the structure. Furthermore, the magnitudes of the local mean aerodynamic drag coefficient and the local standard deviation of the (vortex-induced) lift coefficient were found to be considerably lower than those of a parallel-sided circular cylinder.

A Geometrically Exact Beam Finite Element for Non-Prismatic Strip Beams: The Spatial Case

A new beam finite element for non-prismatic (tapered and curved) beams with thin rectangular cross-section (“strip” beams) is proposed in this paper. The element is geometrically exact and constitutes the extension, to the large 3D displacement and rotation setting, of those proposed by the author for the 2D [R. Gonçalves, Int. J. Struct. Stab. Dyn. 23 (2022) 2350037] and linearized lateral-torsional buckling [R. Gonçalves, Int. J. Struct. Stab. Dyn. 23(12) (2023) 2350139] cases. The element incorporates torsion-related warping, as well as arbitrary mid-line warping, and allows nonlinear tapered geometries, arbitrary initially curved configurations (including pre-twist) and eccentric loads (loads offset from the centroid). All expressions required to implement the proposed element are given in a straightforward vector/matrix format. Several numerical tests are presented to show that the element has a very good predictive capability and a low computational cost, when compared with solutions obtained with refined shell finite element meshes, even for members with a high taper ratio and initial curvature.

Buckling analysis of multi-span non-uniform beams with functionally graded graphene-reinforced foams

This paper conducts the buckling analysis of multi-span functionally graded (FG) beams reinforced by three-dimensional graphene foams (3D-GFs) restrained by elastic supports. The graphene foams are considered as graded variation in the thickness direction according to four different porosity distributions. The width and height of the non-uniform beams vary in the longitudinal direction in accordance with the power-law principle, and the multi-span beams consist of two types of optional beams. The governing equations of buckling behavior are derived based on the Timoshenko beam theory and the principle of virtual displacements, and solved by the discrete singular convolution (DSC) method. The purpose of this paper is to obtain the critical buckling load of FG 3D-GFs reinforced beams under the consideration of variable cross-section and multi-span beams with 2–4 spans. The effect of porosity coefficients, slenderness ratio, and spring constants on the buckling characteristic also are studied. The results suggest that the taper ratio of beams and the configuration of multi-span beams lead to remarkable changes in the critical buckling load of beams.

Dynamical behavior of viscoelastic functionally graded tapered rotors partially filled with liquid

In this study, the dynamics and stability of a viscoelastic functionally graded tapered rotor partially filled with liquid are investigated. It is assumed that the radius of the rotor varies linearly, while the density and elastic modulus change exponentially along the longitudinal direction of the rotor. The Kelvin–Voigt model is utilized to describe the viscoelastic material. The governing equations of motion of the rotor system are established via Hamilton's principle. By using the Laplace transform and the Galerkin method, the characteristic equation of the system is obtained. Then, the complex frequencies of the system are computed in the first order on the basis of the characteristic equation. The critical divergence and flutter rotating speeds are acquired. The stability of the rotor system with viscoelastic effects is examined. Finally, the effects of the main parameters including the gradient parameter, taper ratio, hollowness ratio, mass ratio, cavity ratio, and the viscoelastic coefficient on the dynamical behavior of the system are discussed, respectively. The results show that the stability of the system is strongly dependent on these parameters. Also, the results indicate that the viscoelasticity of the material mainly affects the stability evolution of the rotor system.

ANN model for predicting the elastic critical buckling coefficients of prismatic tapered steel web plates under stress gradients

Tapered steel plate girders are commonly used in large span industrial structures and composite bridges. The tapered thin steel web plates under stress gradients in such structures may be susceptible to elastic local buckling. An efficient and robust Artificial Neural Network (ANN) model is developed and presented in this paper for predicting the elastic critical buckling coefficients of prismatic tapered steel webs under stress gradients. More than 4000 samples are used in extensive parametric analyses of tapered web plates with simply supported edges. The ANN model recognizes important features associated with tapered plates, including the tapering ratio of the plate, aspect ratio, and stress gradient. A dataset containing 4665 records is developed for the training, validation, and testing of the ANN model developed. Two main ANN models are developed. The first model consists of a single hidden layer with neurons varying from 5 to 11. The second model consists of two hidden layers, with 8 neurons in the first layer and 6 neurons in the second layer. The accuracy of these models is thoroughly evaluated. It is found that the developed ANN model with two-hidden layers has superior performance than other models. The developed ANN can be employed to accurately predict the elastic critical buckling coefficients of prismatic tapered steel webs under stress gradients.

Aerodynamic loads of tapered tall buildings: Insights from wind tunnel test and CFD

Tapered modifications have been widely utilized for tall buildings to reduce their wind effects in practical engineering. However, the flow mechanisms caused by tapering and relevant empirical models for wind loads estimations of tapered tall buildings are still unknown. In this study, both wind tunnel test and CFD were used to study the aerodynamic performance of tapered tall buildings. Taken the CAARC standard tall building model as the benchmark model, another four modified models with taper ratio of 0.05, 0.10, 0.15 and 0.20 were designed and tested by pressure measurements and large eddy simulation (LES). The variations of wind pressure coefficients, local wind force coefficients, base moment coefficients, wind load power spectrum and vertical coherence function of five models with different taper ratios were discussed and compared. Also, the streamline of mean and fluctuating velocity around tapered tall building models are provided for better understanding of the flow mechanisms. The results showed that aerodynamic performance of the tapered tall buildings has been improved effectively, especial for across-wind effects. This study aims to provide reference for aerodynamic optimization design of tapered tall buildings.