Measuring bench for investigation of mixing process in ultrasonic mass-transfer apparatus
In the article the laboratory measuring equipment for investigation of mixing in the ultrasonic mass-transfer apparatus is described. The experimental results of testing the equipment during dissolving of crystalline substance in liquid medium with the help of high-intensity ultrasonic vibrations are considered.
Cavitation produced by Ultrasonics
The problem of cavitation produced by ultrasonic vibration is examined theoretically. Equations are developed which describe the motion of a gas-filled cavitation bubble in a liquid medium subjected to alternating pressure; the case of an empty cavity is also considered Information is obtained concerning the distribution of fluid pressures and velocities in the medium near the bubble surface during the motion It is suggested that these theoretical conclusions may be used to show how the intensity of the various effects of cavitation will depend on ultrasonic frequency and intensity. In particular, it is predicted that all cavitation phenomena will diminish and finally disappear as the frequency is raised The important part played by the nucler from which the cavitation bubbles grow is emphasized.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.