Plain water jet noise emission: effect of stand-off distance variation

The stand-off distance is one of the running parameters which has a considerable influence on the noise emission generated by different mine engineering applications of high pressure water jet technology. As a part of a broader research programme aimed to the definition of the role played by operating parameters in sound power emission of plain water jets, a set of tests was conducted to correlate the measured sound power levels (1/3-octave band spectral levels) with the corresponding stand-off distances, for different combinations of pressure and nozzle diameter. The paper illustrates the procedures adopted and the results obtained, highlighting the influence of stand-off distance on plain water jet sound power level and providing some indications about the noise contribution of different jet portions.