ABSTRACT
The concepts of velocity triangles, blade angles, and nozzle angles are introduced in this chapter. Along with these, the velocity components, including the absolute velocity of the fluid, are described in terms of the blade velocity and relative velocity. Using the momentum equation, the most fundamental equation that governs turbomachinery, namely, Euler’s equation, is derived. Then, by applying the energy equation across the rotor, the energy transfer is written in terms of the kinetic energies. This leads to the definition of degree of reaction, which is the ratio of the static enthalpy change to the stagnation enthalpy change across the rotor. Next to be introduced is the utilization factor, which is a measure of the efficiency of the machine from a theoretical perspective. Then, using the concept of maximum utilization, the differences between impulse machines (those with degree of reaction) and 50% reaction machines are discussed with particular reference to the energy produced in each case.
