Helical Wire Research Articles

Thermal-hydrodynamic and exergetic study of two-phase flow in helically coiled pipe with helical wire insert

This paper presents a multi-objective experimental study, to enhance the thermal performance of the helically coiled pipe. The main objective of this study is the hydrothermal evaluation of single-phase (water) flow and two-phase flow (air-water) transition through a helically coiled tube at the presence and absence of helically coiled wire. Water flow rate was varied from 2 l/min to 8 l/min and air flow rate was varied from 1 l/min to 5 l/min which makes the volume fraction (VF) range of 0.110–0.714. Thermal-frictional and exergetic behavior of two-phase flow for a helically coiled tube with a helical wire insert have been studied. Results show that in exergy efficiency inside helical tube without turbulator for single-phase flow is 87% higher than when the turbulator is inserted. The second law analysis demonstrated that the exergetic efficiency decreases by the increment of VF and water flow rate. Generally, when pressure drop increment is less important than heat transfer augmentation, simultaneous use of two-phase flow and turbulator is recommended. Conversely, single-phase flow with turbulator is recommended when the desired pressure drop is low.

Double-periodic Josephson junctions in a quantum dissipative environment

Embedded in an ohmic environment, the Josephson current peak can transfer part of its weight to finite voltage and the junction becomes resistive. The dissipative environment can even suppress the superconducting effect of the junction via a quantum phase transition occurring when the ohmic resistance ${R}_{s}$ exceeds the quantum resistance $R{}_{\text{q}}=h/{(2e)}^{2}$. For a topological junction hosting Majorana bound states with a $4\ensuremath{\pi}$ periodicity of the superconducting phase, the superconductor-insulator phase transition is shifted to $4R{}_{\text{q}}$. We consider a Josephson junction mixing the $2\ensuremath{\pi}$ and $4\ensuremath{\pi}$ periodicities shunted by a resistor, with a resistance between ${R}_{q}$ and $4{R}_{q}$ such that the two periodicities promote competing phases. Starting with a quantum circuit model, we derive the nonmonotonic temperature dependence of its differential resistance resulting from the competition between the two periodicities, the $4\ensuremath{\pi}$ periodicity dominating at the lowest temperatures. The nonmonotonic behavior is first revealed by straightforward perturbation theory and then substantiated by a fermionization to exactly solvable models when ${R}_{s}=2R{}_{\text{q}}$: the model is mapped onto a helical wire coupled to a topological superconductor when the Josephson energy is small and to the Emery-Kivelson line of the two-channel Kondo model in the opposite case. We also settle the compact vs extended phase controversy: introducing a compact phase variable across the junction, associated with a discrete charge, we rigorously prove that it is effectively replaced by an extended phase variable in presence of the environment.

VIV response of risers with large aspect ratio and low rigidity using a numerical scheme based on wake oscillator model

The crossflow (CF) response of a flexible riser subjected to vortex-induced vibration (VIV) has been carried out using numerical simulation based on wake oscillator model for different aspect ratio (L/D), flexural rigidity (EI), mass ratio (μ), and the axial tension (Θ). Experiments were conducted on a scale model with a shear flow profile. The numerical model has been validated by comparing it with VIV responses obtained from experiments for shear flow profile. Parametric studies have been performed using the numerical model to obtain the crossflow root-mean-square (RMS) displacement along the length for L/D range of 100 to 3000, the flexural rigidity of 50 to 2870 MPa, mass ratio of 1.955 to 10, and axial tension of 0 to 3000 N for uniform flow profile. The results of the shear flow profile were presented with those obtained from equivalent uniform flow (equivalent mean velocity). The VIV response indicates that the standing wave pattern occurs for L/D < 1500. In contrast, the travelling wave pattern was observed for L/D = 3000 and indicated the wave pattern is mixed for a transition range of L/D = 1500. It was also observed that the response mode is highly dependent on L/D, EI, and shear flow profile during independent on mass ratio. The VIV displacement response of flexible risers with helical wires reduces by 90% compared with riser without helical wire for a riser diameter to wire diameter ratio of 10 and pitch to riser diameter ratio of 8 in uniform flow.

A Wideband OAM Antenna Based on Chiral Harmonic Diffraction

An orbital angular momentum (OAM) antenna based on chiral harmonic diffraction of spoof surface plasmon polaritons (SSPP) is demonstrated in this letter. Due to the diffraction of the helical wire, SSPP is transformed into the high-purity OAM mode. The operation frequency is determined by SSPP, and the topological charge is manipulated by modulating the harmonic order. Additionally, this system achieves a frequency-controlled beam-scanning characteristic in a wide bandwidth from 7.8 to 12.6 GHz, and the measurement data agrees well with the theoretical analysis and the simulation results. Furthermore, the OAM antenna validated in this letter is compact, easy-fabricated, and robust.The underlying principle opens up a new train of thought for generating OAM mode and paves the versatile applications involving wireless communication.

Numerical Investigation of the Effect of Edge Length of Square Helical Wires on Heat Transfer and Pressure Drop

Heat transfer and applications are among the most important research topics of the industry. The most important factor investigated in this paper is to achieve high heat transfer with less energy. Efforts to improve heat transfer in heat exchangers are an example of this. In this study, the effect of the length of the square helical wires placed in the circular pipe on the heat transfer and pressure drop was investigated numerically. All results were obtained using the k-ℇ turbulence model in the ANSYS FLUENT module. The equations used in the verification were compared with the Dittus-Boelter equation and the Nusselt number friction factor in the turbulent regime with numerical results. It has been observed that the results of the smooth pipe obtained numerically and the results of the empirical relations are quite close to each other. The cross-sectional length of the inserted helical wires is 3, 4, and 5 mm. The pitch ratio of the placed helical wires is 1. The Reynolds number research range is between 5175 and 24,575. According to the obtained results, both the Nusselt number and the friction factor increase with increasing edge length. In addition, higher efficiency is obtained at a low Reynolds number according to the thermo-hydraulic thermal performance criterion (PEC). The highest PEC was seen in the helical wire with a cross-section length of 3 mm, with a value of 1.25. However, it is observed that the PEC of 5 is greater than 4 and 3 with increasing Reynolds number.

Magnetic Driven Double Curved Conical Microhelical Robot

AbstractThe swimming performance of the magnetic driven microhelical robot is mainly determined by its geometric structure. In this research, the existing swimming mathematical model of the microhelical robot is extended by the microelement method, so that it can be used to calculate the swimming speed of the double curved conical microhelical robot (DCCMHR) below the step‐out frequency. Then, the swimming performance of the microhelical robot with different geometric characteristics is explored through simulation experiments, and the structure of DCCMHR is further optimized by analyzing the influence of geometric parameters such as helix angle, helical length, helical wire diameter, cone angle, and the number of thread on the swimming performance of the robot. Compared with the traditional microhelical robot, the swimming speed of the improved microhelical robot can be increased by about 1.2 times, and the stability can be increased by about 25%, which provides a good foundation for the future application of microhelical robot in complex environment, such as minimally invasive surgery, drug delivery, cell transportation, living detection and so on.

Design &amp; Optimization of Large Cylindrical Radomes with Subcell and Non-Orthogonal FDTD Meshes Combined with Genetic Algorithms

The word radome is a contraction of radar and dome. The function of radomes is to protect antennas from atmospheric agents. Radomes are closed structures that protect the antennas from environmental factors such as wind, rain, ice, sand, and ultraviolet rays, among others. The radomes are passive structures that introduce return losses, and whose proper design would relax the requirement of complex front-end elements such as amplifiers. The radome consists mostly in a thin dielectric curved shape cover and sometimes needs to be tuned using metal inserts to cancel the capacitive performance of the dielectric. Radomes are in the near field region of the antennas and a full wave analysis of the antenna with the radome is the best approach to analyze its performance. A major numerical problem is the full wave modeling of a large radome-antenna-array system, as optimization of the radome parameters minimize return losses. In the present work, the finite difference time domain (FDTD) combined with a genetic algorithm is used to find the optimal radome for a large radome-antenna-array system. FDTD uses general curvilinear coordinates and sub-cell features as a thin dielectric slab approach and a thin wire approach. Both approximations are generally required if a problem of practical electrical size is to be solved using a manageable number of cells and time steps in FDTD inside a repetitive optimization loop. These approaches are used in the full wave analysis of a large array of crossed dipoles covered with a thin and cylindrical dielectric radome. The radome dielectric has a thickness of ~λ/10 at its central operating frequency. To reduce return loss a thin helical wire is introduced in the radome, whose diameter is ~0.0017λ and the spacing between each turn is ~0.3λ. The genetic algorithm was implemented to find the best parameters to minimize return losses. The inclusion of a helical wire reduces return losses by ~10 dB, however some minor changes of radiation pattern could distort the performance of the whole radome-array-antenna system. A further analysis shows that desired specifications of the system are preserved.

Local & Average Heat Transfer and Friction Factor Characteristics of a Flow through a Helical Wire Coil for Turbulent Flow Conditions

Heat transfer augmentation is essential for numerous industrial applications. The flow through a helical coil is one of the most efficient and effective techniques of heat transfer enhancement due to the provision of a large surface area. The present study is focused on the thermo-hydraulic performance of turbulent flow through a helical coil, made up of copper with a curvature ratio of 0.0519 (d/D) and pitch equal to 50 mm using water as a test fluid. The objective of the present study is to reveal the influence of secondary flow, centrifugal force, and Reynolds number (Re) on local velocity, local heat transfer coefficient in a helical coil. The values of average heat transfer and friction factor at different Re for a flow through a helical coil are compared with corresponding values for a flow through a smooth tube. The numerical results are presented for the Re number range at inlet conditions of the helical coil from 5000 to 20000 in the increment of 2500 under constant heat flux conditions. Numerical results indicate that there is a circumferential variation of local velocity and local Nusselt number (Nu) values concerningthe inner and outer sides of the helical coil. The values of average heat transfer are observed to be 150 to 200% more than the smooth tube values with increased pressure drop.

A multi-director continuum beam finite element for efficient analysis of multi-layer strand cables

This study presents a multi-director continuum beam finite element developed for efficient analysis of multi-layer strand cables. The beam element is derived from the continuum mechanics based beam formulation incorporating multi-directors and cross-sectional elements to describe the helical geometries of wires that constitute the strand cables. The main advantage of the present continuum beam formulation is that complex geometries of strand cable and inter-wire motions can be addressed in the framework of the beam kinematics regardless of the numbers of layers and subordinate helical wires. This approach enables simple modeling together with efficient analysis, and allows both geometric and material nonlinearities to be considered. In addition to its excellent accuracy, the proposed beam element model requires a significantly reduced number of degrees of freedom compared to conventional three-dimensional solid finite element models for cable analysis. Through several numerical examples, the predictive ability of the proposed beam model is demonstrated.

Scaling Metal‐Elastomer Composites toward Stretchable Multi‐Helical Conductive Paths for Robust Responsive Wearable Health Devices

Stretchable electronics have advanced rapidly and many applications require high repeatability and robustness under various mechanical deformations. It has been described here that how a highly stretchable and reliable conductor composite made from helical copper wires and a soft elastomer, named eHelix, can provide mechanically robust and strain-insensitive electronic conductivity for wearable devices. The reversibility of the mechanical behavior of the metal-elastomer system has been studied using finite element modeling methods. Optimal design parameters of such helical metal-elastomer structures are found. The scaling of multiple copper wires into such helical shapes to form a Multi-eHelix system is further shown. With the same elastomer volume, Multi-eHelix has more conductive paths and a higher current density than the single-eHelix. Integrations of these eHelix stretchable conductors with fabrics showed wearable displays that can survive machine-washes and hundreds of mechanical loading cycles. The integration of the eHelix developed by us with a wearable optical heart rate sensor enabled a wearable health monitoring system that can display measured heart rates on clothing. Furthermore, Multi-eHelix conductors are used to connect flexible printed circuit boards and piezoresistive sensors on a tactile sensing glove for the emerging sensorized prosthetics.

Application of analytical model in the prediction of dynamic responses and fatigue damage of flexible risers: Part II – Dynamic analysis of flexible risers in large-scale domain using a direct moment correction method

In recent years, the dynamic responses of flexible risers have been the focus of many researchers. Most flexible risers undergo a substantial level of irregular motion from environmental loadings, which involves a continuous slip of helical wires. The slip of helical wires especially leads to a hysteretic effect by reducing the bending stiffness, making it hard to predict the dynamic responses of flexible risers. The current study, as an extension to Part I, presents a new large-scale dynamic analysis method for flexible risers. The suggested method creates a large-scale model for the dynamic analysis that considers a geometric and bending nonlinearity of flexible risers. The kinematics of each beam element is formulated based on a Green-Lagrangian strain and the interaction with the seabed, providing a realistic analysis of flexible risers. In particular, the current study introduces a direct moment correction method that modifies the internal force vector using an improved analytical model. The improved analytical model is assigned at each node of the large-scale model and estimates an accurate bending hysteresis curve considering the effect of shear deformation and varying tension. The suggested method corrects the bending moment and shear force of all beam elements based on the bending hysteresis curves obtained from the improved analytical model, by which a complex bending behavior of flexible risers is reflected in a large-scale domain. As a result, this study achieves a more accurate prediction of the dynamic responses and fatigue damage of flexible risers. A new dynamic analysis program, called OPFLEX, is developed herein based on the suggested analysis method. Using the developed program, the current study conducts several numerical investigations to identify the effect of the shear deformation and varying tension. Consequently, it is confirmed that the shear deformation of internal layers reduces the fatigue damage of helical wires by delaying the increase of internal stress. It is also identified that the effect of varying tension deteriorates the fatigue life of flexible risers through a continuous change of contact pressure during bending.

Application of analytical model in the prediction of dynamic responses and fatigue damage of flexible risers: Part I – Improvement of analytical model considering shear deformation and varying tension effects

Flexible risers have been widely utilized for the transfer of oil and gas products from a well to production units. The components of flexible risers, unlike steel risers, experience complex contact phenomena during bending. The contact between helical wires and adjacent layers especially causes a significant level of bending nonlinearity, making it hard to estimate the structural responses. Accordingly, a large-scale dynamic analysis of flexible risers usually involves an analytical model that predicts the bending moment and axial stress of helical wires based on theoretical approaches. The analytical model consists of an axis-symmetrical model and a bending model. Among them, the bending model plays a critical role in the prediction of the bending responses of flexible risers. The conventional bending models usually neglect the shear deformation of internal layers and continuity of sliding force, which leads to a significant error of analysis. Furthermore, the previous bending models assume that the contact pressure on helical wires is constant during bending. In real operating conditions, however, most flexible risers experience a considerable change of tension that governs the slip of helical wires. Hence, the current study presents a new dynamic analysis method for flexible risers. The suggested analytical model improves the bending model based on an accurate estimation of the internal strain field considering the shear deformation and continuous sliding force. Also, this study proposes a stiffness update method to reflect the effect of varying tension in the dynamic analysis. The presented method updates the bending property of flexible risers considering the continuous change of the contact pressure from varying tension. For the validation of suggested method, the current study carries out numerical simulations with a pure bending and varying tension for the internal diameter 7 inches flexible risers. It is identified that the suggested analytical model provides accurate analysis results. Moreover, it is found that the effect of varying tension gives a significant impact on the bending behavior of flexible risers by changing the slip condition of helical wires. Part I of this series of papers describes the detailed formulation method for the analytical model and with some verification examples. The suggested analytical model is expanded to the large-scale dynamic analysis in Part II for the investigation of the effect of shear deformation and varying tension.

In situ growth of copper-based metal-organic framework on a helical shape copper wire as a sorbent in stir-bar sorptive extraction of fenthion followed by corona discharge ion mobility spectrometry

In this paper, a helical copper wire, coated with copper-benzene-1,4-dicarboxylic acid metal-organic framework (Cu-BDC) was used as a sorbent for stir-bar sorptive extraction of fenthion from water and fruit samples. The homogenous coating was fabricated through two simple and fast steps. The chemical conversion of copper substrate to copper hydroxide nanotubes (Cu(OH)2 NTs) was performed in an alkaline solution and then Cu-BDC was formed through a neutralization reaction. Corona discharge ion mobility spectrometry in positive mode was applied for the detection of fenthion. To improve the sensitivity of the method, some synthesis and extraction parameters affecting the extraction efficiency such as benzene-1,4-dicarboxylic acid concentration, ionic strength, sample pH, stirring rate, extraction temperature, and extraction time were investigated. The linear dynamic range between 0.5 and 80 μg L−1 and detection limit of 0.1 μg L−1 were obtained under optimal conditions. The intra- and inter-day relative standard deviations were less than 6.4 and 8.6%, respectively. The applicability of the method was examined for the analysis of different samples (i.e., well water, agricultural wastewater, and orange). The recovery for the determination of fenthion in spiked samples varied from 88 to 111%.

Convective heat transfer and friction factor characteristics of helical strip inserted annuli at turbulent flow

Helical baffles, wire coils, and rectangular ribs are used to improve the annular fluid flow turbulence and heat transfer performance. Among the different insert types, loose-fitted helical baffles or strips are of major interest because of their better performance. Tight-fitted helical strips can show better performance in the annular flow because they can act as a fin besides acting as a swirl generator compared to loose-fitted ones. For that reason, a three-dimensional (3D) computational fluid dynamics (CFD) study is performed to investigate the heat transfer and pressure drop characteristics of turbulent flow (4000 ≤ Re ≤ 10000) at annuli with and without tight-fitted helical strip inserts. Annuli with 0.6, 0.7, and 0.8 annuli diameter ratio (ADR) are studied for plain and helical strip inserts with pitch ratios (PRs) of 1, 2, and 3. Result showed that higher heat transfer coefficient (HTC) and friction factor were found for insert-fitted annuli compared to those of plain annuli. HTC increased with increase in Re and ADR and decrease in insert PR. The best performance was for 0.8-ADR insert-fitted annuli: 171%–207% (1 PR), 82%–105% (2 PR), and 56%–75% (3 PR) compared to 0.8-ADR plain annuli. Although HTC increased with increase in ADR, the Nusselt number (Nu) decreased because of the smaller hydraulic diameter. Nu increased with increase in Re but decreased with higher ADR and insert PR. The friction factor increased with decrease in insert PR and ADR and decreased with increase in Re. A figure of merit (FoM) was used to combine the benefit of heat transfer enhancement and the drawback of higher pressure drop. The FoM ranged from 0.9 to 1.3, 0.94 to 1.22, and 0.92 to 1.24 for ADR values of 0.6, 0.7, and 0.8, respectively, for a specific Re range. The heat transfer performance obtained was in the order of 3 PR < 2 PR < 1 PR for insert-fitted annuli, but the FoM followed 1 PR < 2 PR < 3 PR because of a much higher pressure drop for lower PR. This study confirms that inserts improve heat transfer, which is better at lower Re.

Heat transfer characteristics of enhanced cooling tube with a helical wire under oscillatory flow in Stirling engine

Improving the heat transfer of cooler is favourable to reduce the cold end temperature and dead volume of Stirling engine. In this study, the effect of the implementation of a helical wire to a cooling tube of the reciprocating flow in Stirling engine was investigated numerically. The performance of helical wire with different geometric parameters and under different operating conditions were studied. The results show that the streamlines were helical and the fluid temperature homogeneity was improved. With the same size, the temperature drop of enhanced tube was 1.08–1.54 times as much as that of smooth tube. When obtaining the same outlet temperature, the diameter of smooth tube was 52% of that of enhanced tube with same tube length (for p = 12.5 mm, h = 1.2 mm, d0 = 1.6 mm, l = 180 mm, Remax = 13,816, Reω = 207). Thus, the amount of smooth tube needed to increase to 3.7 times as much as that of enhanced tube. In another case (for p = 12.5 mm, h = 1.2 mm, d0 = 1.6 mm, d = 5 mm, Remax = 13,816, Reω = 207), the length of smooth tube should be increased to above 2 times as much as that of enhanced tube with same tube diameter. Therefore, the tube with a helical wire could significantly enhance the heat transfer or decrease the size of cooler. Compared to smooth tube, the extra pressure drop by enhanced tube was accounts for no more than 0.6% of minimum pressure in Stirling engine (for Remax = 13,816, Reω = 207). It only accounted for 9.6–13.1% of the pressure drop of a regenerator. Therefore, the enhanced cooling tube with remarkable heat dissipation capacity and relatively low loss of pressure drop will present great application potential in Stirling engine.

Numerical and computational analysis of radiation characteristics of dielectric loaded helical antenna

In this paper, a full-wave analytical theory has been proposed based on the field theory approach and numerically solved for computing radiation properties of the dielectric-loaded helical antenna (DLHA). First, the dispersion equation is analytically derived from the source-free Maxwell equation subject to necessary boundary conditions. Then radiation characteristics of DLHA are derived using the field theory approach. The effect of polarization current arising due to dielectric on radiation properties is addressed for the first time in the case of DLHA. All the numerical analysis is carried out in MATLAB. To further validate the results, computation analysis is carried out using CST Microwave Studio Software. From the result, it was observed that when the circumference of the antenna (C) is comparable to the wavelength (λ) corresponding to operating frequency then the wave propagates axially through the helical wire in the axial direction and is radiated in the end-fire direction whereas when the circumference is not equal to the wavelength then the wave gets radiated in the normal direction and attenuated in the axial direction. Also, the impedance bandwidth of the antenna is increased from 2.5% to 52.9% and the gain is increased from 8.35 dB to 11.5 dB due to teflon loading. Finally, the antenna prototype is fabricated, measured, and compared with the numerical and computational results. A close agreement between the analytical, computational, and measurement results are found.

Omni-Directional Wideband Antenna Array with Solar Cells

Abstract Distributed sensor networks are becoming more and more widespread due to their substantial benefits to our daily lives. These sensors, in most cases, are distributed in nature and even may require mobility. This, in turn, implies omnidirectional collector units to collect the data from various sensors at arbitrary directions. This work summarizes the performance outcomes of various integrated wide-band antenna structures and solar power generation topologies to achieve equal gain in all directions. Purpose of the array in this instance is contrary to enhance the received signal levels in all directions. Low-cost solutions ranging from the planar helical printed circuit board (PCB) designs to vertical wire helical antennas were investigated. An optimum design structure for multiple ISM bands (868 MHz to 915 MHz) was proposed and characterized considering the cost, size, directional coverage and most significantly RF sensitivity and range of the overall design. The final water-resistant solar-powered wideband transceiver front-end has provided range improvement and omnidirectional radiation pattern. The system consists of a 190mm x 190mm low-cost FR4 substrate and a Wilkinson network to combine the power of 8 helical wire antennas sprinkled along with the solar cells. The self-contained, Sun-powered unit resulted in 4.5-dB sensitivity improvement in measurements.

Guided wave‐based cable damage detection using wave energy transmission and reflection

Health monitoring of cables in civil engineering structures is a great challenge, because their integrity directly affects the safety of the whole structure. A magnetostrictive (MS) transducer-based guided wave method for cable damage detection is presented in this study. A wave energy-based method is proposed for damage localization and severity assessment. The wave energy transmission coefficient at the damage location is presented as a measure for the damage condition. Firstly, the wave dispersion properties were analyzed on a steel strand with seven helical wires using a semi-analytical finite element (SAFE) method. Then, the selection of exciting frequency and design of the MS transducer were carried out based on the SAFE analysis results. Numerical and experimental studies were performed on multiple cases of wire breakage and corrosion using the pitch-catch method. Time-of-flight information on the wave packets reflected from the damages was used for damage localizations, while wavelet coefficients were used to accurately analyze wave energy transmission and reflection. It has been found that the damage locations and damage conditions can be determined accurately using the proposed method.

Numerical study on wake galloping of tandem circular cylinders considering the effects of mass and spacing ratios

The mass and spacing ratios of parallel circular cylinder structures change over a wide range in engineering applications. In this study, the effects of mass ratio, spacing ratio and helical wires on the wake galloping of tandem circular cylinders are investigated by LES turbulence model at the subcritical Reynolds number regime. The upstream cylinder is fixed and the downstream one is free to respond in the transverse direction. The characteristics of wake galloping of tandem circular cylinders are systematically studied for the cases of mass ratios m∗ ​= ​1.8, 200 and spacing ratios x0/D ​= ​4, 8 and 12. A critical velocity of wake galloping is derived as a function of mass ratio and lift coefficient slope using a wake-stiffness-based model. The suppression of wake galloping by the 4-start helical wires is examined and the maximum amplitude of vibration is found to decrease by 63% because of the positive added damping generated by helical wires.

Experimental investigation on wake-induced vibrations of the hangers of suspension bridges based on three-dimensional elastic test model

Large amplitude wind-induced vibrations of the hangers have been observed on several suspension bridges, and the underlying mechanism is not clearly clarified until now. In this study, the mechanism of wake-induced vibration of the hanger was studied by using wind tunnel tests based on three-dimensional (3-D) elastic test model. First, a new method was proposed to design 3-D elastic test model to accurately simulate a long cable in wind tunnel with a limited height. Second, taking the No.2 hanger of the Xihoumen Bridge as the background, a 3-D elastic hanger model was designed and manufactured by using the new method, and a series of wind tunnel tests were carried out within the spatial region of 3 ≤ P ≤ 10 and 0°≤α ≤ 20° to obtain the wake-induced responses of the hanger. The results show that obvious vibrations of the downstream cable are observed under all wind velocities tested (3 ~ 14 m/s), and the unstable region of the downstream cable tends to increase with the increase of wind velocity. Third, the effects of the structural damping on the wake-induced vibrations of the hangers were studied in detail. The results show that the wake-induced cable vibration of the hangers is not totally mitigated even if the structural damping ratio is as high as 1.37%. Finally, the effectiveness of two kinds of countermeasures (helical wires and spacers) on the wake-induced vibrations of the hangers of suspension bridges was experimentallystudied. The results show that the helical wire can suppress the wake-induced vibration of the test case of P = 7, α = 5°, but have no effect for the test case of P = 3.5, α = 20°. It seems that the spacer is a reasonable countermeasure to mitigate the wake-induced vibrations of the hangers of suspension bridges.