Chapter 7 - Pulsed liquid jets for hydrodemolition

Abstract

This chapter explains material loading due to water drop impingement including stresses due to drop impingement, material response to drop impingement, parameter effects and resistance parameters, and multiple drop impingement. It also talks about material loading due to cavitation with reference to fundamentals of cavitation and the material response to cavitation. Cavitation can be observed during the impact of liquids to solid and liquid surfaces. Cavitation is the growth and implosion of gas-filled bubbles in a liquid. Basically, flow cavitation and acoustically induced cavitation can be distinguished; however, the first type is more common in practice. Any impinging water jet exhibits two pressure levels: an impact pressure in the very early stage of jet impact and a stagnation pressure that is established after the impact period. The chapter explains the types of pulsed jets, and their formation. Pulsed jets can be of two forms: low frequency and high frequency. Both of these techniques involve the modulation of continuous high-speed water jets. The chapter also provides information about water cannons, ultrasonically modulated jets, self-resonating jets, pressure and volume modulation, and cavitating jets. The two most important parameters of pulsed liquid jets are loading intensity and loading frequency. The chapter concludes with a discussion on the practical applications of pulsed jets.