Search results
1 – 10 of 10Zenghui Wang, Xu Meng and Xingang Yu
The liquid lithium-lead breeding blanket in the international thermonuclear experimental reactor is one of the major international concerns and one of the potential conceptual…
Abstract
Purpose
The liquid lithium-lead breeding blanket in the international thermonuclear experimental reactor is one of the major international concerns and one of the potential conceptual designs for the fusion reactor.
Design/methodology/approach
Reduced activation ferritic-martensitic steels are being considered for application in future fusion technology as the relevant structural material, which will be in contact with the lithium-lead breeding material.
Findings
According to the test results, comprehensive evaluations of these findings have been performed to determine the wastage rates and mechanisms for the conceptual design of the fusion reactor.
Originality/value
From micro to macro, systematic cross-scale models are needed for the understanding of corrosion/wastage mechanisms in fusion reactor engineering applications.
Details
Keywords
THE British Standard 4231 : 1967 “Viscosity Classification for Industrial Liquid Lubricants” together with BS 4475 : 1969 “Specification for Straight Mineral Lubricating Oils”…
Abstract
THE British Standard 4231 : 1967 “Viscosity Classification for Industrial Liquid Lubricants” together with BS 4475 : 1969 “Specification for Straight Mineral Lubricating Oils” constitute a real step forward for the lubrication world. Not only do they contribute clarity to their respective subjects, they also enable an overall classification of all lubricants and hydraulic fluids based on a common theme to be composed. BS 4231 enables the viscosities of all fluid lubricants including hydraulic media to be identified within one dimensionally rational scale. Though it is specifically for straight mineral oils, BS 4475 suggests a segregation of quality levels appropriate to other than straight oils.
Most of this concluding article is concerned with surveying the corrosion of lead and its alloys in acids and alkalis of all types. As a considerable proportion of the lead…
Abstract
Most of this concluding article is concerned with surveying the corrosion of lead and its alloys in acids and alkalis of all types. As a considerable proportion of the lead consumed each year by industry is used for making grids for lead‐acid batteries, special attention has also been given to corrosion problems in this field. The newer applications for lead include its use in nuclear energy plant as a shielding material, and as a reactor coolant, and the corrosion problems arising under such conditions are discussed.
Shvidkiy Evgeny, Igor Sokolov, Kirill Bolotin and Valery Zakharov
The purpose of this paper is to determine how the shape of the container affects the efficiency of a traveling magnetic field (TMF) stirring.
Abstract
Purpose
The purpose of this paper is to determine how the shape of the container affects the efficiency of a traveling magnetic field (TMF) stirring.
Design/methodology/approach
The modeling approach is based on finite element software Comsol which includes harmonic electromagnetic (EM), transient CFD and particle tracing modules. For evaluating efficiency of stirring the particle, homogenization parameter is used.
Findings
It has been determined that the use of an elliptical cylinder-shaped vessel allows better heat removal from the side surface and, at the same time, the stirring efficiency does not drop significantly.
Practical implications
The results of the work can be used in the design of EM stirring installations in which exothermic reactions occur.
Originality/value
The transient simulation of particle transport in a TMF-driven melt flow gives the opportunity to estimate the efficiency of stirring process in different vessel shapes.
Details
Keywords
Describes the structure and rheological characteristics of soap based greases and how the thickener retains the oil phase. Illustrates the thixotropic behaviour and effect of time…
Abstract
Describes the structure and rheological characteristics of soap based greases and how the thickener retains the oil phase. Illustrates the thixotropic behaviour and effect of time of shearing on friction, film thickness, noise energy loss in grease lubricated contacts. Shows how friction can be less with grease than with oil.
Details
Keywords
Any consensus about the effects of dihedral angle on hover rigidity of rotary-wing unmanned aerial vehicles (RW-UAVs) does not exist in the literature. There are researchers who…
Abstract
Purpose
Any consensus about the effects of dihedral angle on hover rigidity of rotary-wing unmanned aerial vehicles (RW-UAVs) does not exist in the literature. There are researchers who state that the dihedral angle has an effect on flight stability and researchers who claim the opposite. The discord stems from the different approaches of these groups to the concept of “stability,” the fact that they conduct experiments whose measurements are largely influenced by environmental conditions, and the physical assumptions are not similar. On the other hand, there is no study examining the effect of dihedral angle on the maneuverability of drones either. This study aims to analytically reveal the consequences of dihedral angles in RW-UAVs in terms of flight agility and maneuverability.
Design/methodology/approach
Dihedral angle examinations on both hover rigidity and maneuverability are carried out analytically. Equations of motions for a multicopter’s rigid body with a dihedral angle under two different conditions (zero and nonzero dihedral angles) are derived. Numerical simulations are conducted by defining the simulation parameters, and then displacement graphics for the center of mass are interpreted.
Findings
The presence of a dihedral angle makes the multicopter platforms behave like a pendulum, and this pendulum motion affects the disturbance rejection and the planar maneuver capabilities of multicopters. Since deflections can be spread to the orthonormal axes thanks to rotation about a pivot, net deflections of the geometric center may be diminished. Besides, pendulum motion eases the maneuvers with yaw rotations since the required rotation might occur without rotors’ revolution per minute changes.
Practical implications
Proposed dihedral angle implementation may enhance the hover stiffness and maneuverability capabilities of multicopters which, in turn, raise the performance of the drones.
Originality/value
This paper presents the analytical basis for the dihedral angle's effects on flight stability and agility.
Details
Keywords
Michele Ciofalo and Fabrizio Cricchio
The buoyancy‐driven magnetohydrodynamic flow in a cubic enclosure was investigated by three‐dimensional numerical simulation. The enclosure was volumetrically heated by a uniform…
Abstract
The buoyancy‐driven magnetohydrodynamic flow in a cubic enclosure was investigated by three‐dimensional numerical simulation. The enclosure was volumetrically heated by a uniform power density and cooled along two opposite vertical walls, all remaining walls being adiabatic. A uniform magnetic field was applied orthogonally to the gravity vector and to the temperature gradient. The Prandtl number was 0.0321 (characteristic of Pb–17Li at 300°C), the Rayleigh number was 104, and the Hartmann number was made to vary between 0 and 2×103. The steady‐state Navier–Stokes equations, in conjunction with a scalar transport equation for the fluid's enthalpy and with the Poisson equation for the electrical potential, were solved by a finite volume method using a purposely modified CFD code and a computational grid with 643 nodes in the fluid. Emphasis was laid on the effects of increasing the Hartmann number on the complex three‐dimensional flow and current pattern.
Details
Keywords
The purpose of this paper is to develop new semi-empirical heat transfer correlations for turbulent flow of liquid metals in the tubes, and then to compare these correlations with…
Abstract
Purpose
The purpose of this paper is to develop new semi-empirical heat transfer correlations for turbulent flow of liquid metals in the tubes, and then to compare these correlations with the experimental data. The Prandtl and Reynolds numbers can vary in the ranges: 0.0001 ≤ Pr ≤ 0.1 and 3000 ≤ Re ≤ 106.
Design/methodology/approach
The energy conservation equation averaged by Reynolds was integrated using the universal velocity profile determined experimentally by Reichardt for the turbulent tube flow and four different models for the turbulent Prandtl number. Turbulent heat transfer in the circular tube was analyzed for a constant heat flux at the inner surface. Some constants in different models for the turbulent Prandtl number were adjusted to obtain good agreement between calculated and experimentally obtained Nusselt numbers. Subsequently, new correlations for the Nusselt number as a function of a Peclet number was proposed for different models of the turbulent Prandtl number.
Findings
The inclusion of turbulent Prandtl number greater than one and the experimentally determined velocity profile of the fluid in the tube while solving the energy conservation equation improved the compatibility of calculated Nusselt numbers, with Nusselt numbers determined experimentally. The correlations proposed in the paper have a sound theoretical basis and give Nusselt number values that are in good agreement with the experimental data.
Research limitations/implications
Heat transfer correlations proposed in this paper were derived assuming a constant heat flux at the inner surface of the tube. However, they can also be used for a constant wall temperature, as for the turbulent flow (Re > 3,000), the relative difference between the Nusselt number for uniform wall heat flux and uniform wall temperature is very low.
Originality/value
Unified, systematic approach to derive correlations for the Nusselt number for liquid metals was proposed in the paper. The Nusselt number was obtained from the solution of the energy conservation equation using the universal velocity profile and eddy diffusivity determined experimentally, and various models for the turbulent Prandtl number. Four different relationships for the Nusselt number proposed in the paper were compared with the experimental data.
Details
Keywords
The case deals with the issue of gaining a sustainable competitive advantage (SCA) in the solar energy market. After completing the case, the student will be able to– develop and…
Abstract
Learning outcomes
The case deals with the issue of gaining a sustainable competitive advantage (SCA) in the solar energy market. After completing the case, the student will be able to– develop and apply conventional models of competitive advantage and core competency;– comprehend each step of the business process from a core competency viewpoint;– consider the value of sustainability solutions from a strategic standpoint; and– offer practical templates for creating and implementing a strategy.
Case overview/synopsis
This case depicts the challenges faced by Exalta in gaining a SCA because of the imitation of its products by competitors. Exalta, formed in 2008, was among the well-known innovative companies in the solar energy industry in India. In the first 12 years, the company focused primarily on unmet customer demand and developed innovative solar products to address those demands. Overall, over 300 products were launched in the initial years to address the new emerging customer demands. Solar AC, bikes and ventilators were among the popular ones. However, all of its product technology was copied by competitors. In 2021, troubled Exalta was incubated at IIT-Kanpur primarily for a single product, “Magic Inverter,” with substantial funding and IP protection. Despite attempts, Exalta could not capture a recognized market share. In this case, the company’s founder and CEO, Ashutosh Verma, is contemplating two options to gain an SCA: hold the existing and new products or fold the old ones and continue with one or two flagship products, i.e. Magic Inverter and Solar AC.
Complexity academic level
Graduate, postgraduate level and executive-level courses.
Supplementary materials
Teaching notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes.
Subject code
CSS 11: Strategy.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/EEMCS-12-2022-0526/
Details
Keywords
Kaiqiang Wang, Shejuan Xie, Hongwei Yuan, Cuixiang Pei, Zhenmao Chen and Weixin Li
In this paper, numerical modelling and dynamical response analysis were performed for the HL-2M vacuum vessel (VV) and shielding plates (SPs) during a plasma disruption by using…
Abstract
Purpose
In this paper, numerical modelling and dynamical response analysis were performed for the HL-2M vacuum vessel (VV) and shielding plates (SPs) during a plasma disruption by using an updated ANSYS parametric design language (APDL) code developed by the authors. The purpose of this paper is to investigate the influence of the SPs on the dynamical response of VV owing to a transient electromagnetic (EM) force and to optimize the design of SPs in view of the minimization of the structural dynamic response.
Design/methodology/approach
The Lagrangian approach, i.e. the moving coordinate scheme developed by the authors, was updated to tackle the EM-mechanical coupling effect in the dynamic response analysis of the VV-SPs system due to the transient EM force during plasma disruptions. To optimize the structural design of HL-2M SPs, the influence of the key parameters of SPs, i.e., the side length, thickness and material properties, was clarified on the basis of the numerical results and an optimized design of SPs was obtained.
Findings
The updated APDL code of the Lagrangian approach is efficient for the transient dynamical response analysis of the VV-SPs system owing to the EM force. The SP of a smaller side length, larger thickness tungsten material better mitigates the dynamical response of the VV-SPs system.
Originality/value
The Lagrangian approach was updated for the EM–mechanical coupling dynamical response analysis of the VV-SPs system, and the influence of the SP parameters on the dynamical response of the VV-SPs system of HL-2M Tokamak was clarified.
Details