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.
On Cavity Formation in Water
Phenomena involving the tensile strength of water have been studied by a kinetic method—high speed motion photography of the rapid movement of a blunt glass rod (5 mm diameter) in a narrow (16 mm inside diameter) glass tube of water. Special precautions have been taken to remove all hydrophobic patches and small gas masses (gas nuclei) but to retain the dissolved gas (air at one atmosphere) in the water. If the rod surface contained gas nuclei, or was hydrophobic and free of gas nuclei, cavitation occurred at the rear end when the velocity was less than 3 meters/sec., but if completely hydrophilic and free of gas nuclei, the velocity could be 37 meters/sec. or 83 miles/hour without cavitation. Addition of a detergent (diactyl sodium succinate) to the water did not prevent cavitation at a low velocity with the hydrophobic rod free of gas nuclei. Movement of a rod in pure corn syrup (viscosity 20.1 poises), free of gas nuclei, left a large cylindrical cavity that collapsed in a matter of hundredths of a sec...