Across a turbomachine, or any of its components, the following statement of energy conservation applies:

where 1 and 2 refer to the flow inlet and exit stations, respectively. The variables in equation (3.1) are defined as follows:

• q is the heat energy gained per unit mass of the working medium,

• w _s is the shaft work exerted per unit mass,

• h is the specific (per unit mass) enthalpy, and

• V is the local velocity.

Ignored in equation (3.1) is a familiar right-hand-side term representing the change in potential energy (caused by, say, the streamwise change in elevation), as it is immaterial in dealing with gas-turbine-engine applications.