Topic
Critical speed
About: Critical speed is a research topic. Over the lifetime, 2764 publications have been published within this topic receiving 31365 citations.
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TL;DR: In this article, the authors derived the analytical formula of eddy current braking force by a subdomain method considering the skin effect of the induction plate, and, subsequently, the characteristics of peak braking force and critical speed are analyzed.
Abstract: In the eddy current braking system of high-speed maglev, the peak braking force and the critical speed are key factors determining the performance of eddy current braking force. In this paper, the analytical formula of eddy current braking force is derived by a subdomain method considering the skin effect of the induction plate, and, subsequently, the characteristics of peak braking force and critical speed are analyzed. The analytical model is set up in a 2D Cartesian coordinate system. The Poisson equations in each subdomain are listed by treating the vector magnetic potential as a variable. By combining the boundary conditions between two adjacent subdomains, the expressions of eddy current density and magnetic density in the induction plate are obtained. Then, the analytical formula of the eddy current braking force is obtained by the Ampere force formula. The results of finite-element analysis confirm the validity of the analytical calculation. The methods of improving the performance of eddy current braking force under high speed are proposed by parametric analysis of peak braking force and critical speed, which provides guidance for the design of the eddy current braking system in high-speed maglev.
10 citations
01 Jan 2009
TL;DR: In this paper, the effect of dimensionless parameters e (which is 2 g/ω 2 d, where g, ω and d denotes gravitational acceleration, container rotation rate and inner diameter of liquid cylinder) and G (number of times the gravity) was studied as variation of rotation speed, viscosity and aspect ratio of the mould.
Abstract: An attempt has been made to investigate the various parameters affecting the fluid behaviour, partially filled in a rotating cylinder. When the cylinder is rotating at ‘high’ speed, a liquid forms a hollow cylinder. Different patterns are observed in the fluids for the rotatioal speeds below a critical speed. This study should give us some insight into molten metal behaviour during centrifugal casting. An extensive experimental investigation is required to obtain an appropriate functional relationship by knowing and understanding some dimensionless parameters. Here the effect of dimensionless parameters e (which is 2 g/ω 2 d, where g, ω and d denotes gravitational acceleration, container rotation rate and inner diameter of liquid cylinder) and G (number of times the gravity) was studied as variation of rotation speed, viscosity and aspect ratio of the mould.
10 citations
TL;DR: In this paper, a structural impedance approach is extended for the dynamic analysis of pipe structures conveying fluid flow and the critical speed associated with the dynamic stability is calculated and compared with available analytical and experimental results.
10 citations
TL;DR: In this article, the multivariable irrational, hyperbolic and circular function, input-output relationship for the system was derived and the frequency response method was employed in the determination of the critical speed condition.
10 citations
Patent•
17 May 1979
TL;DR: In this paper, a rotor assembly for a gas turbine engine having a critical speed characteristic well above the operating speed is described, and various construction details which enhance axial stiffness of the rotor assembly and which shield a portion of the disk from working medium gases are developed.
Abstract: A lightweight, rotor assembly for a gas turbine engine having a critical speed characteristic well above the operating speed is disclosed. Various construction details which enhance the axial stiffness of the rotor assembly and which shield a portion of the disk from working medium gases are developed. The rotor assembly employs a frustoconical member to connect a shaft to the disk.
9 citations