tailieunhanh - ACOUSTIC WAVES – FROM MICRODEVICES TO HELIOSEISMOLOGY_2

Tham khảo sách 'acoustic waves – from microdevices to helioseismology_2', kỹ thuật - công nghệ, kĩ thuật viễn thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Part 3 Acoustic Waves as Manipulative Tools 15 Use of Acoustic Waves for Pulsating Water Jet Generation Josef Foldyna Institute of Geonics of the ASCR v. v. i. Ostrava Czech Republic 1. Introduction The technology of a high-speed water jet cutting and disintegration of various materials attained considerable growth during the last decades. Continuous high-speed water jets are currently used in many industrial applications such as cutting of various materials cleaning and removal of surface layers. However despite the impressive advances made recently in the field of water jetting substantial attention of number of research teams throughout the world is still paid to the improvement of the performance of the technology its adaptation to environmental requirements and making it more beneficial from the economic point of view. An obvious method of the water jetting performance improvement is to generate jets at ultra-high pressures. The feasibility of cutting metals with pure water jets at pressures close to 690 MPa was investigated already in early nineties of the last century Raghavan Ting 1991 . Such a high pressure however induces extreme overtension of high-pressure parts of the cutting system which has adverse effect on their lifetime. An alternate approach as shown in this chapter is to eliminate the need for such high pressures by pulsing the jet. It is well known that the collision of a high-velocity liquid mass with a solid generates short high-pressure transients which can cause serious damage to the surface and interior of the target material. The liquid impact on a solid surface consists of two main stages see Fig. 1 . During the first stage the liquid behaves in a compressible manner generating the so-called water-hammer pressures. These high pressures are responsible for most of the damage resulting from liquid impact on the solid surface. The situation shortly after the initial impact of the liquid on the solid surface is illustrated in Fig. 2. After .

• Kĩ thuật Viễn thông
• Numerical Investigations
• Topological Singularities
• Acoustic Wave
• Important Equations
• Anisotropic Drilling
• Investigative Tools
• Ultrasound Attenuation
• Experimental on heat transfer
• Numerical investigations on heat transfer and friction loss
• Functionalized GNP nanofluids
• The GNP water
• The thermal fluid systems
• Characterization
• Continuum Mecha
• Problem Domain
• Finite Volume Methods
• Finite Element Methods
• Mathematics as science
• Mathematics and art
• Recreational mathematics
• Millennium Prize Problems
• Numerical analysis
• Lead free solder
• Digital image correlation
• Plastic zone
• Full field strain measurement
• Fracture parameter
• Advanced materials and devices
• Electric field analysis
• Dielectrophoresis based microfluidic channel
• Circulating tumor cells
• Continuous cell separation