Cavitation And The Centrifugal Pump

This practical reference describes the occurrence of cavitation in a centrifugal pump, and how unacceptable cavitation can be avoided. It explains cavitation problems such as hydraulic performance loss, hydrodynamically or thermodynamically induced surging, and cavitation erosion. General guidelines for acceptable operation conditions, such as, net positive suction head (NPSH) margins and minimum flowrates, are presented along with evidence and logic for these proposed guidelines.

Centrifugal pump technology involves a broad spectrum of flow phenomena, which have a profound impact on design and operation through the achieved efficiency, the stability of the head-capacity characteristic, component failure due to fatigue, as well as material damage caused by cavitation, hydro-abrasive wear or erosion corrosion. Operation and life cycle costs of pumping equipment depend to a large extent on how well these phenomena and the interaction of the pump with the system are understood. The book comprises thirteen chapters covering: theory of centrifugal pump impeller, design of mixed flow impellers, pump casing, hydraulic performance, leakage-disk friction and mechanical losses, water hammer, special operating conditions, and its applications. The book also describes cavitation in pumps, and how unacceptable cavitation can be avoided with the aid of an inducer or using a bleeding system. It explains cavitation problems such as hydraulic performance loss, hydro-dynamically or thermodynamically induced surging, and cavitation erosion/corrosion. The book aims to be simple as is compatible with reasonably complete treatment of the subject. The mathematics has been kept as elementary as possible and many of the standard proofs have been simplified. This book is intended for professional engineers, researchers, specialist students, plant operators and maintenance personnel, plant engineers, and consulting engineers.

Pumps are commonly encountered in industry and are essential to the smooth running of many industrial complexes. Mechanical engineers entering industry often have little practical experience of pumps and their problems, and need to build up an understanding of the design, operation and appropriate use of pumps, plus how to diagnose faults and put them right. This book tackles all these aspects in a readable manner, drawing on the authors' long experience of lecturing and writing on centrifugal pumps for industrial audiences.

Centrifugal Pumps describes the whole range of the centrifugal pump (mixed flow and axial flow pumps are dealt with more briefly), with emphasis on the development of the boiler feed pump. Organized into 46 chapters, this book discusses the general hydrodynamic principles, performance, dimensions, type number, flow, and efficiency of centrifugal pumps. This text also explains the pumps performance; entry conditions and cavitation; speed and dimensions for a given duty; and losses. Some chapters further describe centrifugal pump mechanical design, installation, monitoring, and maintenance. The various types and applications of pumps in the light of the particular design features involved are addressed in other chapters. This book is authoritative, informative, and thought-provoking to an exceptional extent. It establishes a notable advance in the progress of the art of the designer and manufacturer of centrifugal pumps, to the material advantage of the user.

The structure of a hydraulic machine, as a centrifugal pump, is evolved principally to satisfy the requirements of the fluid flow. However taking into account the strong interaction between the pump and the pumping installation, the need to control the operation, the requirement to operate at best efficiency in order to save energy, the provision to improve the operation against cavitation and other more specific but very interesting and important topics, the object of a book on centrifugal pumps must cover a large field. The present book examines a number of these more specific topics, beyond the contents of a textbook, treating not only the pump's design and operation but also strategies to increase energy efficiency, the fluid flow control, the fault diagnosis.

The book focuses on the fluid dynamics of cavitation with special reference to high power density turbopumps, where it represents the major source of performance and life degradation. While covering the more fundamental aspects of cavitation and the main kinds of cavitating flows, there is focus on the hydrodynamics and instabilities of cavitating turbopumps. The book also illustrates the alternative approaches for modeling and engineering simulation of cavitating flows.

Specifically for the pump user, this book concentrates on the identification and solution of problems associated with existing centrifugal pumps. It gives specific examples on how to modify pump performance for increased efficiency and better quality control, which turn into long-term cost savings. Some basic theory is included to give the reader greater understanding of the problems being encountered and attacked.

This last, the education of pump users, is precisely what this book was intended to do. To what extent we must have achieved our purpose, our readers must decide. My good friend and associate, J. T. (Terry) McGuire, and I have been working very closely together for a long time. Our view of engineering problems and of their solutions coincide to an astonishing degree. When I was asked to prepare a second edition of my book Centrifugal Pumps, it was logical that I turned to Terry and suggested that he be my coauthor on this project. He agreed to do so, and his cooperation has been most valuable, both in improving the resultant work and in easing my burden. It would be presumptuous on my part to pretend that nothing has changed in the technology of centrifugal pumps during the 30 years since I prepared the manuscript for the first edition of this book. Let me, then, speak of some of these changes.