Fundamentals of Cavitation

ISBN-13: 9789048166183 / Angielski / Miękka / 2010 / 306 str.

Jean-Pierre Franc; Jean-Marie Michel

Opis

Why are propeller blades of speedboats strongly eroded? Why does a syringe have to be filled slowly in order to avoid the formation of a vapour cavity near the piston? Why does a pump for watering the garden not work efficiently if it is placed too high above the ground water level? These questions, and many others taken from day to day experience, refer to situations which apparently have no connection between them, except for the fact that the motion of a liquid in part of the system plays an essential role.

Cavitation science is that part of liquid physics which addresses the motion of liquids near -or beyond- the limit of vaporization. Generally, vaporization occurs if liquid velocities are large, causing pressure to decrease below a critical value at which the liquid continuum is broken at one or several points. Vapor cavities appear there and various unexpected effects follow for the system such as noise, lower performance, vibrations, wall erosion For a long time, it was believed that cavitation phenomena should be avoided entirely because of the generally negative character of their consequences. However, over the years it appeared that such a constraint could be costly, though not necessarily justified on scientific grounds. A limited development of cavitation - if carefully defined and controlled - can be allowed. This promotes the development of high speed hydrodynamics and hydraulics.

The present book is aimed at providing a comprehensive presentation of cavitation phenomena in liquid flows. It is further backed up by the experience, both experimental and theoretical, of the authors whose expertise has been internationally recognized. A special effort is made to place the various methods of investigation in strong relation with the fundamental physics of cavitation, enabling the reader to treat specific problems independently. Furthermore, it is hoped that a better knowledge of the cavitation phenomenon will allow engineers to create systems using it positively. Examples in the literature show the feasibility of this approach.

Spis treści

-Foreword; Hiroharu Kato. -Preface. Symbols. -1: Introduction - The main features of cavitating flows. 1.1. The physical phenomenon. 1.2. Cavitation in real liquid flows. 1.3. Specific features of cavitating flow. 1.4. Non-dimensional parameters. 1.5. Some historical aspects. -2: Nuclei and cavitation. 2.1. Introduction. 2.2. Equilibrium of a nucleus. 2.3. Heat and mass diffusion. 2.4. Nucleus population. References. -3: The dynamics of spherical bubbles. 3.1. Basic equations. 3.2. The collapse of a vapor bubble. 3.3. The explosion of a nucleus. 3.4. The effect of viscosity. 3.5. Non-linear oscillations of a bubble. 3.6. Scaling considerations. 3.7. Stability of a spherical interface. References. -4: Bubbles in a non-symmetrical environment. 4.1. Introduction. 4.2. Motion of a spherical bubble in a liquid at rest. 4.3. Non-spherical bubble evolution. 4.4. The path of a spherical bubble. References. Appendix to Section 4.3.3. -5: Further insights into bubble physics. 5.1. The effect of compressibility. 5.2. Bubble noise. 5.3. Some thermal aspects. 5.4. A typical numerical solution. References. Appendix to Section 5.1.3. -6: Supercavitation. 6.1. Physical aspects of supercavities. 6.2. Supercavity flow modeling using steady potential flow theory. 6.3. Typical results. 6.4. Axisymmetric cavities. 6.5. Specific problems. References. Appendix: singular behavior at detachment. -7: Partial cavities. 7.1. Partial cavities on two-dimensional foils. 7.2. Partial cavities in internal flows. 7.3. The cloud cavitation instability. 7.4. Wakes of partial cavities. 7.5. Thermal effects in partial cavitation. References. Appendix: sonic velocity in a liquid/vapor mixture with phase change. -8: Bubbles and cavities on two-dimensional foils. 8.1. Attached cavitation. 8.2. Traveling bubble cavitation. 8.3. Interaction between bubbles and cavities. 8.4. Roughness and cavitation inception. References. -9: Ventilated supercavities. 9.1. Two-dimensional ventilated supercavities. 9.2. Axisymmetric ventilated supercavities. 9.3. Analysis of pulsating ventilated supercavities. References. -10: Vortex cavitation. 10.1. Theoretical results. 10.2. The non-cavitating tip vortex. 10.3. Cavitation in a tip vortex. References. -11: Shear cavitation. 11.1. Jet cavitation. 11.2. Wake cavitation. References. -12: Cavitation erosion. 12.1. Empirical methods. 12.2. Some global results. 12.3. Basic hydrodynamic mechanisms of energy concentration. 12.4. Aggressiveness of a cavitating flow. 12.5. Insight into the material response. References. Index.