Introduction

This chapter introduces the book on fluid mechanics and the thermodynamics of turbomachines. The book examines, through the laws of fluid mechanics and thermodynamics, the means by which the energy transfer is achieved in the chief types of turbomachines, together with the differing behavior of individual types in their operations. The turbomachines are devices in which energy is transferred continuously flowing fluid by the dynamic action of one or more moving blade rows. Two main categories of turbomachines are identified—those that absorb power to increase the fluid pressure or head (ducted and unducted fans, compressors, and pumps) and those that produce power by expanding fluid to a lower pressure or head (wind, hydraulic, steam, and gas turbines). Methods of analyzing the flow processes differ depending upon the geometrical configuration of the machine. The most fundamental and valuable principles in fluid mechanics is Newton's second law of motion. The momentum equation relates the sum of the external forces acting on a fluid element to its acceleration, or to the rate of change of momentum in the direction of the resultant external force. The chapter presents the basic physical laws of fluid mechanics and thermodynamics, developing them into a form suitable for the study of turbomachines such as the continuity of flow equation, the first law of thermodynamics and the steady flow energy equation, the momentum equation, and the second law of thermodynamics. The energy and entropy equations are introduced in the chapter, along with all-important Euler work equation, which applies to all turbomachines. It also presents important efficiencies such as efficiency of turbines, steam and gas turbines, hydraulic turbines, and compressors and pumps.