ABSTRACT
In this chapter, axial gas turbines, which play an important role in aircraft engines, are discussed. Since such turbines produce comparatively less power than radial turbines, they are often placed in stages in order to produce a meaningful amount of power. Using the concept of repeating stages or normal stages, degree of reaction is defined as the ratio of static enthalpy drop in the rotor to static enthalpy drop across both stator and rotor. Blade loading coefficient and flow coefficient are defined in the context of axial flow using the blade velocity and axial velocity. The concept of small stage efficiency is distinguished from overall adiabatic or isentropic efficiency of the turbine. It is shown that the turbine efficiency is greater than the stage efficiency. The two most common types of axial turbine stages, impulse and 50% reaction, along with the method of estimating the number of stages for the turbine, are discussed in detail. The chapter ends with the rudiments of axial turbine design.
