Rocket Propulsion Elements, 9th Edition

CHAPTER 3NOZZLE THEORY AND THERMODYNAMIC RELATIONS

In rocket propulsion systems the mathematical tools needed to calculate performance and to determine several key design parameters involve the principles from gas dynamics and thermodynamics that describe processes inside a rocket nozzle and its chamber. These relations are also used for evaluating and comparing the performance between different rocket systems since with them we can predict operating parameters for any system that uses the thermodynamic gas expansion in a supersonic nozzle; they allow the determination of nozzle size and generic shape for any given performance requirement. This theory applies to chemical rocket propulsion systems (liquid and solid and hybrid propellant types), nuclear rockets, solar‐heated and resistance or arc‐heated electrical rocket systems, and all propulsion systems that use gas expansion as the mechanism for ejecting matter at high velocities.

Fundamental thermodynamic relations are introduced and explained in this chapter. By using these equations, the reader can gain a basic understanding of the thermodynamic processes involved in high‐temperature and/or pressure gas expansions. Some knowledge of both elementary thermodynamics and fluid mechanics on the part of the reader is assumed (see Refs. 3–1 to 3–3). This chapter also addresses different nozzle configurations, nonoptimum performance, energy losses, nozzle alignment, variable thrust, and four different alternate nozzle performance ...