As a kind of promising noncontact bearings, ultrasonic bearings actuated by smart materials such as lead zirconate titanate ceramics show a good application prospect in high-speed machines and precision-measuring devices. The suspending force is one of the most important parameters that play a dominated role on the bearing’s static and dynamic performance. A suspending force model based on acoustic radiation theory for cylindrical object near sound source is built to predict the radial carrying capacity of an ultrasonic bearing actuated by three piezoelectric transducers. To validate the model, an ultrasonic bearing prototype is developed and a testing system is established. For observing the bearing’s dynamic running performance at high speeds, the bearing’s running experiment is carried out and the rotor center’s trajectory data and frequency spectrum are acquired to analyze the bearing’s dynamic characteristics at high speeds. The suspending force model and running performance experiments will contribute to the design, detection, and test of this type of bearings.
Calcium carbide sludge is a kind of dense paste; when transported by pipeline, the pressure loss is enormous. However, how to calculate the pressure loss accurately has not been solved until now. This article aims to present a new method to build a pressure loss calculation model based on the experimental data of pipeline transportation. To determine the relationship between the pressure loss and the properties of calcium carbide sludge, a new circulating pipeline testing apparatus was designed. The test studied pressure losses arising from changes in the mass concentration of the paste, flow velocity, pipe diameter, and pipe length. Analyzing the obtained data by means of nonlinear curve fitting, the adsorption coefficient and viscosity coefficient were defined and then the calculation formula was deduced. Finally, the calculation formula was verified for a project pipeline with a relatively large diameter equal to φ200 mm and the same parameters as those of industrial applications. The results show that under the appropriate conditions of applying the model, the relative error is less than 20%, so the model can be applied to engineering pressure loss estimation. This method provides a suitable pipe transportation calculation method for dense paste, combining experimental data and theoretical derivation.
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