Abstract
To assess the impingement capability of water jet, submerged water jet discharged from a centralbody nozzle is investigated. Efforts are devoted to both the wavy jet edge and the cavitation phenomenon involved. Three configurations of the central body are examined and jet pressure is fixed at 15 MPa. Jet edge is visualized using high speed photography. Numerical simulation is performed to extract flow parameter distributions in the jet stream and to predict cavity profiles. Furthermore, an impingement experiment with target sandstone samples is conducted as well. The results indicate that both lateral fluctuation amplitude and frequency of the jet stream vary with axial position of the central body. Cavitation tongues of different stream wise dimensions are manifested in the wake flows downstream of the central body. In case of the downstream end of the central body parallel with nozzle outlet section, the largest stream wise dimension of cavitation zone is obtained. Relative to the round nozzle with the same equivalent outlet diameter, the central-body nozzle yields preferable impinging effect.
Highlights
The concept of the central-body nozzle was introduced in 1980s, and this kind of nozzle was used firstly in mining industry [1]
It is expected to provide an in-depth demonstration of features of the centralbody nozzle and cast light upon cavitation phenomenon in submerged water jet
According to statistical results based upon water jets at jet pressures larger than 10 MPa, unsteady characteristics are evident represented by transient variation of flow parameters and the interaction between jet and ambient medium [7] [8]
Summary
The concept of the central-body nozzle was introduced in 1980s, and this kind of nozzle was used firstly in mining industry [1]. As high-pressure liquid moves around a blunt-ended central body fixed inside the flow passage of the nozzle, low-pressure zone might appear immediately downstream of the blunt end, which might. (2014) Flow Characteristics and Cavitation Effect of the Submerged Water Jet Discharged from a Central-Body Nozzle. Flow patterns near the nozzle depend on both nozzle outlet shape and jet pressure [3]. For submerged water jet, measurement of flow parameter distributions is difficult, at high jet pressure [5]. With a thin cylinder intruding into the flow passage of a round nozzle, submerged water jet discharged from a central-body nozzle at jet pressure of 15 MPa is investigated. High speed photography is employed to capture instantaneous fluctuations of jet edge near nozzle outlet. It is expected to provide an in-depth demonstration of features of the centralbody nozzle and cast light upon cavitation phenomenon in submerged water jet
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