text: :q = Heat per unit mass added into the system
  Strictly speaking, enthalpy is a function of both temperature and density. However, invoking the common assumption of a calorically perfect gas, enthalpy can
  be converted directly into temperature as given above, which enables one to define a stagnation temperature in terms of the more fundamental property,
  stagnation enthalpy.
  Stagnation properties (e.g. stagnation temperature, stagnation pressure) are useful in jet engine performance calculations.  In engine operations, stagnation temperature is often called total air temperature.  A bimetallic thermocouple is often used to measure stagnation temperature, but allowances for thermal radiation must be made.