**5. Conclusions**

340 Acoustic Waves – From Microdevices to Helioseismology

Results of the research of effects of pulsating jets on various materials obtained so far indicate that the pulsating jets can be used advantageously for the removal of surface layers of materials and/or "rough" cutting. However, further research will be necessary to be able

> 20 MPa 30 MPa 50 MPa 70 MPa

20 MPa 30 MPa 50 MPa 70 MPa

Fig. 17. Influence of a standoff distance on arithmetic mean roughness (SRa) of the surface created by the action of pulsating fan water jet generated by the fan jet nozzle with

10 20 30 40 50 60 70 80

**Standoff distance [mm]**

Fig. 18. Influence of a standoff distance on average maximum height roughness (SRz) of the surface created by the action of pulsating fan water jet generated by the fan jet nozzle with

10 20 30 40 50 60 70 80

**Standoff distance [mm]**

to use the pulsating water jets in applications of precise cutting.

equivalent of diameter 1.10 mm and spraying angle of 10°

0

0

200

400

600

**SRz [µm]**

800

1000

20

40

60

**SRa [µm]**

80

100

120

equivalent of diameter 1.10 mm and spraying angle of 10°

Presented results of the analytical solution and numerical simulation of the transmission of acoustic waves in high-pressure system represent the first step in gaining knowledge regarding processes of generation and propagation of high-frequency pressure pulsations in the liquid under high pressures and their influence on forming and morphology of pulsating liquid jets.

Results obtained from the visualization of pulsating water jets are used in studying of the characteristics of the jets and to verify results obtained from numerical simulation of the process of generating and forming of pulsating water jets. Laboratory and pilot tests of effects of pulsating water jets on various materials showed clearly the potential of pulsating jets to improve the performance of water jetting technology significantly.

It can be concluded that the research presented in the paper contributed to better knowledge of processes occurring in areas of generation and propagation of high-frequency pressure pulsations in the liquid under high pressure, their influence on forming and morphology of pulsating water jets and effects of the jets on materials. However, it is still necessary to further study problems of the efficient transfer of the high-frequency pulsation energy to longer distances in the high-pressure system. This will enable creation of the highly effective pulsating liquid jet with required properties.
