This study investigates the influences of constant compensations which are produced by capillary or constant flow pump on the dynamic characteristics of a circular worktable supported by a closed-type hydrostatic thrust bearing. The dynamic behaviors of this worktable are analyzed by using Runge-Kutta method to solve the coupled motion equation of worktable and pressure equations of hydrostatic film flow. For various supply pressure parameters, external loads, and varieties of design parameters, the dynamic responses of worktable subjected to both external excitations of harmonic force and step force are simulated, respectively. The results reveal the influences of both constant compensations on the dynamic characteristics of hydrostatic bearing by the different responses of worktable and make the appropriate parameters of design can be found for the worktable-bearing system. The accomplishments of this study will help the designers who deal with the hydrostatic- bearing compensated by constant restrictions to select the design parameters to approach the optimum condition.
Constant flow valves have been presented in industrial applications or academic studies, which compensate recess pressures of a hydrostatic bearing to resist load fluctuating. The flow rate of constant-flow valves can be constant in spite of the pressure changes in recesses, however the design parameters must be specified. This paper analyzes the dynamic responses of DSI-type constant-flow valves that is designed as double pistons on both ends of a spool with single feedback of working pressure and regulating restriction at inlet. In this study the static analysis presents the specific relationships among design parameters for constant flow rate and the dynamic analyses give the variations around the constant flow rate as the working pressure fluctuates.
In this study, the complex phenomena of propagation and interaction of the blast waves impacting on obstacles were visualized and investigated using a numerical method. Three different distances between an immovable wall and a bomb shelter with a square block inside were considered while a blast source is located in front of wall at the same distance from shelter. The transitional shock phenomena were simulated by means of a multi-block mesh system and a flux computational model. Spatial discretization was performed using the Roe's upwind schemes; time integration was achieved via the second-order explicit Hancock method. Proof of the numerical results indicated that those results were in close agreement with the experimental data obtained for the wedge flow. For the cases proved, the geometries of the reflected wave patterns followed by the incident blast waves crossing the immovable wall and impacting inside of bomb shelters were similar. However the height of wall has a dominating impact on the effect associated with different incident blast waves from the same blast source. Meanwhile, different reflected overpressure-time histories and streamlines were observed and analyzed for the results obtained.
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