Insulator Cylinder Research Articles

Analysis of Vibration Characteristics of Cryogenic Insulated Cylinders Based on ANSYS

Abstract To ensure the safety of vehicle mounted cryogenic insulated cylinders during transportation, a finite element model for analyzing the vibration characteristics of vertical cryogenic insulated cylinders considering the frame was established based on ANSYS. The vibration characteristics of vertical cryogenic insulated cylinders under no-load conditions were studied, and the natural frequency patterns of cylinders under different filling rates were compared. The results showed that the connection between the bottom head of the inner liner and the cylinder, the operating frame, and the root of the bottom support were the locations where resonance occurs with larger amplitude. As the filling rate increased, the natural frequencies of each order of the cylinder decreased, and the maximum vibration amplitude of the inner cylinder decreased.

Scattering of Laguerre–Gaussian Beam by a Topological Insulator Cylinder Coated with Metamaterials

A theoretical investigation is presented to study the orbital angular momentum (OAM) beam scattering from a topological insulator (TI) cylinder coated with metamaterials. To calculate the electromagnetic (EM) response of the scattered field, the field equations are modified using Laguerre–Gaussian (LG) potential and plane wave scattering. The response of the metamaterial coated geometry has been reported for Double positive (DPS), Double negative (DNG), Epsilon negative (ENG), and Mu negative (MNG) coating layers, respectively. The normalized bistatic echo widths for the TI cylinder also change by changing the topological charge ( $$l$$ ), the radius of the metamaterial coated layer $$(b)$$ , source frequency $$(f)$$ , and beam waist radius $$({w}_{0})$$ . Our result for $${LG}_{00}$$ beam exactly tones with plane wave scattering as a reference. Numerical results in the form of bistatic echo widths have been calculated. Besides, the prementioned parameters, the influence of OAM mode index on the bistatic echo width is also analyzed. It can be seen that OAM mode number plays major role in controlling the scattering amplitude and intensity.

Sensible Heat Bean Cooker

Alternative cooking energy to replace wood fuels is needed in the African context. Liquified Natural Gas (LNG) is a solution but is still based on burning fossil fuel. Electrical cookers can be an alternative as well. However, for off-grid systems this means electrical batteries are required, as the solar electricity from Photovoltaic (PV) panels is intermittent, and as cooking is also to be made after sunset. Heat storage technologies can provide solutions where available energy is stored in the form of heat for cooking when needed. The challenge is then to develop systems which are robust, safe, and technically simple. A very simple small-scale solution is demonstrated here, for the particular case of cooking beans. An insulated iron cylinder is heated, either in a solar concentrator or by PV-powered heating elements. The stored heat can then be calibrated to the cooking of a given volume of beans. After the cylinder has reached the calibrated temperature during the charging, the pot can be placed and left on the top of the cylinder. When the energy is depleted, the beans should be ready cooked.

Experimental Study of Mixed Convection in a Cavity with a Rotating Cylinder

Mixed convection in a semi-circle enclosure of radius 0.15 m and length 0.75 m is studied experimentally. An insulated rotation cylinder is fixed at the center of the cavity to improve the heat transfer coefficient, the bottom wall of the enclosure is subjected to constant heat flux while the external curved wall is exposed to the ambient temperature. Cavity is placed horizontally and vertically and the angular velocities (62.8,83.73,125.6) rad/s. Results show an improvement of heat transfer coefficient with increasing angular velocity and with the horizontal and vertical cavity positioning.

Fatigue analysis of thermal shrink-fit autofrettage in pressure cylinder using finite element analysis

Autofrettage is the process to find the residual stress properties of the thick cylinder under the high-pressure scenario. Due to the cost and material demands, the elastoplastic behaviour offers better durability result is increased resistance to cracking. One of the main parameters for the cause of cracking is the enormous level of pressure and with the autofrettage process, the durability of the material is boosted up and improves the corrosion cracking resistance. Another factor of autofrettage is the fatigue life of a thick cylinder under stress. The fatigue life of the material can be evaluated by a computerized method analysis to minimize the level of Von-Mises stress under the operating pressure condition. Conducting the computerized analysis by modelling the geometry of the model with frictionless support and acting pressure on the cylinder model. ANSYS finite element modelling is largely utilized tool in the material testing with an advantage of less computing time and cost. Since the results obtained from the simulation progress are actualized with the real-time condition by applying the real constraints in parametric setting and boundary conditions respectively. In this research work, the autofrettage of a thick cylinder is carried out in the finite element modelling using ANSYS workbench 18.1. The modelling is done for the boundary condition of pressure level of 45, 96, 110 and 134 MPa. A 3D model of cylinders is created with the dimension of the inner cylinder of inner radius 15mm, the outer cylinder of outer radius 35mm with the total cylinder wall thickness and length of 20 mm and 250mm respectively. Though the analysis is run for the different pressure limits and autofrettage on the thermal insulated thick cylinder is investigated for the stress parameters under shrink-fit pressure limits. The result from the analysis indicates that the autofrettage pressure at 159 MPa the cylinder withstand pressure beyond the limit it collapsed. Hence, it is evident from the result, the selected AISI 4630 steel material of thick cylinder can withstand the autofrettage under thermal shrink-fit condition under the maximum autofrettage pressure limit of 159 MPa respectively.

Scattering by a magnetized plasma-coated topological insulator cylinder

In the present paper, the scattering characteristics of a magnetized plasma-coated topological insulator cylinder are formulated and analysed graphically. Field equations at each interface are expanded in terms of cylindrical wave vector functions by imposing extended classical wave-scattering theory. By applying the boundary conditions, scattering matrices are obtained in terms of scattered and transmitted coefficients. The obtained results are also compared with published results to display the accuracy of the present formulation under some special conditions. Changes in the bistatic echo widths of the topological insulator cylinder are also recorded by varying the anisotropic plasma parameters (i.e., the applied magnetic field, plasma density and effective collisional frequency).

Wigner transport simulation of (core gate) silicon-shell nanowire transistors in cylindrical coordinates

Gate-all-around silicon nanowire transistors (SNWTs) are recognized as promising candidates to reduce problems due to quantum effects in conventional nano-transistors. In this study we investigate whether structural modification of SNWTs leads to improved performance. A model calculation for a transistor with a channel length of several nanometers requires a quantum transport simulator, and we use a Wigner transport equation (WTE) discretized by a third-order upwind differential scheme (TDS) suggested by Yamada et al. (2009) for quantum transport simulations of gate-all-around silicon-shell nanowire transistors (SSNWTs), core gate SSNWTs (CG-SSNWTs), and independent CG-SSNWTs (ICG-SSNWTs). A WTE discretized by the TDS is known to produce highly accurate results. The SSNWT has a structure in which an insulator cylinder is inserted into the center axis of the SNWT, and the CG-SSNWT has a structure in which a core gate is inserted into the center axis of the SSNWT. The calculations show that the performances of the SSNWTs are improved by introducing the Si-shell structure and the core gate. The ICG-SSNWTs are identical in structure to the CG-SSNWTs, but the outer and core gates are independently biased. The calculations for the ICG-SSNWTs show that the threshold voltage can be controlled using the difference between the core and outer gate voltages.

Echo width of plasma coated topological insulator cylinder

Echo width of plasma coated topological insulator cylinder

In-Depth Analysis and Reflection on Explosion of Welded Insulated Cylinder for Liquid Oxygen

This article provides a comprehensive analysis on an explosion of welded insulted cylinder for liquid oxygen during unloading occurred in a company in 2014. The possible causes of the accidents are deduced through analysis on the operating principles of welded insulated cylinders, explosion energy estimation and related performance tests. On the basis of the accident analysis, this article presents that great importance should be attached to the safety in filling of welded insulated cylinders, replacement prior to filling and regular inspections, and also indicates the gap in currently existing rules on periodic examinations of welded insulated cylinders in China.

Influence of tailored MLI for complex surface geometries on heat transfer

Complex, non-developable surfaces require a tailored multi-layer insulation (MLI) for lowest heat load. The most experiments showing the heat transfer through MLI are performed under quasi-ideal conditions determining the principle insulation quality. But the surface to be insulated in real cryostats implies feed-throughs and other non-developable surface parts. The thermal performance of MLI is degraded significantly at cutting points. To investigate this degrading effect a LN2-filled cylinder with a diameter of 219 mm and a length of 1820 mm was insulated with MLI and the heat load was measured by means of calorimetry. In addition the heat load to an insulated cylinder with eighteen branches was measured. Both cylinders have the same surface of 1.37 m2 for a comparison of the results. This article describes the experiments with different ways of tailoring the MLI for the cylinder with branches and discusses their results. It was shown that the cutting points at the branches have a significant degrading influence on the thermal performance of MLI.

Transport in magnetized nanocylindrical topological insulators

In this work we study the surface states of a topological insulator (TI) cylinder with a magnetization in the radial, azimuthal and axial directions. We derive the eigenenergies and eigenstates, and show that a state with a quantum number associated with the orbital angular momentum incident at a junction between a source TI cylinder and a coaxial drain TI cylinder can only be transmitted and reflected into states with the same quantum number. For cylinders magnetized only in the radial direction, this leads to markedly different behavior in the transmission depending on whether the source magnetization is smaller or larger than the drain magnetization. For azimuthal magnetizations, it results in perfect transmission between two cylinders magnetized to different extents in the azimuthal direction. The restriction of transmission and reflection to states with the same quantum number gives rise to a step-like increment in the transmission from an unmagnetized cylinder to one with an axial magnetization as the energy and magnetization are varied.

Electromagnetic scattering from a topological insulator cylinder placed in chiral medium

We study the scattering of time harmonic electromagnetic plane wave from a topological insulator circular cylinder in chiral medium. Variation of scattering behavior for different values of radii and permittivity of the cylinder is noted when time reversal symmetry is protected and we also studied the scattering behavior when time reversal symmetry is broken. Although scattering behavior of co-polarized component of field is not significantly different from chiral cylinder in chiral medium yet it is found that the same, when time reversal symmetry broken, is similar to scattering from a perfect conductors. Scattering behaviour of cross-polarized field component of topological cylinder in chiral medium is remarkably different from chiral cylinder i.e. it has stronger scattering possibly due to the presence of conducting states near the surface. Moreover, it is noted that the scattering in forward direction for cross-polarized and co-polarized components are not correlated with permittivity but for carefully selected values of permittivity, we can control the scattering behavior of topological insulator circular cylinder.

Scattering from a topological insulator cylinder buried below a slightly rough surface

Electromagnetic scattering from a topological insulator (TI) cylinder buried beneath a rough surface is considered. To account for the interactions of the scattered field and the rough surface, spectral plane wave representation of fields is used along with small perturbation method. Both time-reversal symmetry TI cylinder and time-reversal symmetry broken TI cylinder are considered to evaluate the scattered-transmitted field above the rough surface for different values of the periods of the rough surface and the size of the object. It is observed that co- and cross-polarized field components show a maximum before the time-reversal symmetry is broken. The co-polarized component remains almost constant while the cross-polarized component decreases for time-reversal symmetry broken case.

Scattering from topological insulator circular cylinder buried in a semi-infinite medium

The problem of electromagnetic scattering of a plane wave from a topological insulator (TI) cylinder buried beneath a flat interface is undertaken with the method of analysis based on spectral plane wave representation of fields. Saddle point method is employed to evaluate the involved spectral integrals serving as basis functions in the representations of scattered-reflected and scattered-transmitted fields. The distinctions between the scattering pattern for time reversal symmetry TI cylinder and that of time reversal symmetry broken TI cylinder are pronounced. Results are validated through the comparison with the previously available results.

The thermal stress analysis and structure optimum of neck tube with vertical cryogenic insulated cylinders based on ANSYS

As an important support structure between inner and outer vessel in cryogenic insulated cylinders, the root of neck tube becomes the weakest link because of opening in inner upper end for connecting. The main purpose of this paper is to present a study of thermal stress analysis and structure optimum of the neck tube support system of cryogenic cylinders subjected to internal pressure, self weight, lateral inertia load and temperature difference with the aid of ANSYS tools. The cryogenic cylinders with different height-diameter (H/D) ratios are studied in this study, as well as a wide range of geometries of neck tube. A parametric study of the effects of neck tube on the maximum stresses in the vessels under different loading conditions was performed by finite element analysis method. As that the stress concentration mainly occurs at the vicinity area of the opening of the inner upper heads, how reinforcement ring affects the stress distribution is also discussed. The study results will serve as the available data for structure design and optimization of cryogenic cylinders.

The persistent charge and spin currents in topological insulator Bi2Se3 nanowires

We investigate theoretically the surface states of three-dimensional topological insulator cylinder nanowires analytically and numerically. In contrast to the conventional semiconductor cylinder nanowires, these surface states exhibit unique massless Dirac dispersion and interesting transport properties. We find that the persistent charge current and persistent spin current, i.e., the Aharonov-Bohm oscillation, can be induced by the driven magnetic flux. The amplitude of persistent charge current shows an oscillating behavior with increasing the electron density.

Simultaneous two-axis vibration measurement of a nonmetallic cylinder by electromagnetic induction and metallic foil loops

This work presents a method based on electromagnetic induction for the simultaneous non-contact measurement of two-axis lateral vibrations of a nonmetallic cylinder. The suggested method employs two pairs of hollow metallic loops, four pairs of permanent magnets and two solenoids. When the cylinder vibrates, eddy currents are generated in the metallic loops due to electromagnetic induction. The current in one pair of loop is induced by the lateral vibration in one direction, while the other by the lateral vibration in the perpendicular direction. The induced currents can be sensed through the remotely installed solenoids. While the proposed technique can be useful for the vibration measurement in hot or insulated cylinders, for which a contact type sensor is hardly applicable, the present study is focused on its underlying measurement mechanism and fundamental experiments. To this end, two-axis vibrations and frequency response functions of a thin nonmetallic cylinder were measured simultaneously by the proposed sensor. They were compared with those extracted by using commercial accelerometers to check the working performance of the proposed measurement technique. The effects of some parameters in the proposed technique, such as the length of the loop, were also investigated.

Numerical simulation and experimental analysis of heat transfer through the neck tube into vertical cryogenic insulated cylinders

The neck tube is an important support structure in cryogenic insulated cylinders. The heat flux from the outside environment through the neck tube into the cryogenic liquid occupies a great proportion of the total heat leak and can be more than half of the total heat loads. In this paper, conjugate convective-conductive heat transfer model between wall and the cold vapor in conditions of natural discharge is numerically investigated. Also a liquid nitrogen boil-off method was adopted in experiments to validate the result of numerical simulation. Experimental results indicate more favorable agreement with conjugate heat transfer (CHT) model compared with simple solid heat conduction (SSHC) model by ANSYS software. And the convection between the wall and vapor is also calculated. The research and results can provide reference in design for neck tube of the cryogenic cylinder.

An Improved Helical Resonator Design for Rubidium Atomic Frequency Standards

The slow-wave structure (SWS) can be used as the resonant cavity for rubidium atomic frequency standards (RAFSs), in which the longitudinal component of the magnetic field can enable the rubidium atoms' participation in the stimulated transitions. In this paper, an improved helix SWS based on good propagation characteristics as a helical resonator for RAFS is designed. The theoretical analysis is performed together with the simulations of the propagation characteristics. Using finite integration technique (FIT), the simulated results, including phase velocity, on-axis interaction impedance, and distribution of the magnetic field, are implemented and compared with the experimented results. The effects of the different helical pitch and dielectric material in the insulator cylinder on the propagation characteristics are analyzed in detail. The analyzed results show that smaller helical pitch and proper usage of dielectric material in the insulator cylinder can make the propagation characteristics of the helix SWS superior. The improved helix SWS for RAFS adapts a smaller helical pitch and is loaded with the dielectric material of Teflon in the insulator cylinder. This structure can reduce the cavity volume to 14.7 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The short-term stability of RAFS is up to 1.28 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> /¿ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> , and the frequency stability is 2.0 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> /°C at the temperature range of -20°C to +55°C.

Flow and Heat Transfer of Natural Convection in Horizontal Annulus With a Heating Element on Inner Cylinder

Experiments have been performed to study natural convection flow and heat transfer in a horizontal annulus when a square heating element is positioned at different locations on the inner insulated cylinder. The annulus is filled with water and has cylinder to cylinder diameter ratio of 3. The square heating element is small and has the width to annulus gap width ratio of 1/6. The range of Rayleigh number studied is approximately from 1.9×106 to 3.3×107. It has been found that the flow pattern, the temperature distribution around the inner cylinder wall, and the local heat transfer rate around the outer cylinder are very sensitive to the location of the heating element. The heating element Nusselt numbers at various locations on the inner cylinder are obtained and well correlated against the Rayleigh number to the 1/3 powers. A maximum in the correlation parameter C is obtained when the heating element is placed 90 deg from the bottom.