A momentum integral analysis is presented for the incompressible, steady, axisymmetric flow in a short vortex chamber of the type commonly used in vortex valves. The analysis is developed with the aid of flow visualization photographs and considers the interaction which occurs between the main vortex core flow and the viscous chamber end wall boundary layers. The radial pressure distributions predicted by the analysis compare favorably with measured end wall static pressure distributions.
The design and performance of an active controller for a pantograph which collects current for a high-speed train are considered. A dynamic model of the pantograph/catenary system is described and control objectives are established. A design which incorporates a frame-actuated controller and requires only a single measurement is described. Over an array of train speeds, the contact force variation with the actively controlled pantograph is 50 percent less than for the equivalent passive pantograph system.
The importance of elevated guideway/vehicle dynamics to the design of advanced ground transportation systems is discussed and the general vehicle-suspension-guideway interaction problem is outlined. Simplifying assumptions valid for many practical beam-type elevated guideway systems are described including the Bernoulli-Euler beam assumptions, support conditions, and simplified vehicle models. The theoretical and experimental literature on beam-guideway/vehicle dynamics is reviewed and recent computer-based analytical techniques (lumped mass, finite difference and modal analysis) are discussed. Available simulation programs are described and published results for wheeled, air cushion and magnetically levitated vehicles operating over beam-elevated guideways are reviewed. The influences of critical system parameters on guideway deflection and vehicle vibrational acceleratior (ride comfort) are illustrated through simple limiting case analyses. Low ratios of vehicle-suspension to guideway natural frequency and distribution of vehicle weight over finite pressure pads as in air or magnetic suspensions reduce guideway structural requirements for specified ride comfort. Continuous guideway beams on simple supports provide lower static deflection and greater dynamic range than simply supported single or multiple span beams. Severe resonance problems which may occur in synchronous vehicle systems are illustrated using a point-force vehicle model.
High-performance pantograph design requires control of pantograph dynamic performance. Many pantograph dynamic models developed to aid in the design process have employed two degrees of freedom, one for the head mass and one for the frame. In this paper, the applicability of these models to symmetric and asymmetric pantograph designs is reviewed. Two degree-of-freedom models have been shown to be appropriate to represent a number of symmetric pantograph designs. To represent the asymmetric designs considered in this paper, an additional degree of freedom representing frame dynamics has been introduced to yield a three degree-of-freedom nonlinear dynamic performance model. The model has been evaluated with experimental data obtained from laboratory dynamic testing of an asymmetric pantograph.
Analyses are developed to determine the dynamic performance of vehicles interacting with single, multiple, and continuous span elevated structures. Operating conditions in which multispan resonant conditions occur are identified, and the resulting resonant amplitudes computed. Guideway design examples considering tracked, levitated vehicles are described to illustrate the influence of span configuration and vehicle speed and suspension properties upon guideway span design for vehicle-guideway systems required to provide specified passenger comfort levels. For the 150 and 300 mph (242 and 483 km/h) vehicle systems considered, continuous and multispan guideway configurations were found to have reduced span material requirements in comparison to single span systems which provide the same level of passenger comfort.
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