Rockets#

This section introduces the CT-ROCKET module for computing the performance of chemical rocket propulsion systems using a one-dimensional flow approximation. The schematic in Fig. 17 depicts the physical components considered in this analysis:

  • Injector (inj), where propellants are introduced at negligible velocity.

  • Combustion chamber (c), a region of constant cross-sectional area \(A_c\), bounded by an adiabatic wall.

  • Converging nozzle section (c-t), with decreasing area \(A(x)\), which accelerates the subsonic flow toward the throat.

  • Throat (t), the location of minimum area \(A_t\) where the flow becomes sonic.

  • Diverging nozzle section (t-e), with increasing area \(A(x)\), which enables supersonic expansion and thrust generation.

../_images/sketch_rocket.svg

Fig. 17 Schematic of a chemically reacting rocket flow including chamber, throat, and expanding nozzle.#

The solver is implemented in the RocketSolver class and provides tools to evaluate the idealized performance of a propellant system under a set of simplifying assumptions:

  • One-dimensional flow.

  • Uniform cross-sectional area in the chamber.

  • Negligible inlet velocity at the injector.

  • Infinitely fast chemistry at injection.

  • Adiabatic combustion.

  • Isentropic expansion through the nozzle.

  • Homogeneous mixture (no slip or temperature difference between phases).

  • Ideal gas equation of state.

  • Continuity of temperature and velocity between gaseous and condensed species.

Thermochemical states are handled through the CT-EQUIL module. The formulation follows the methodology originally developed in NASA’s CEA code [Gordon and McBride, 1994].

Two limiting cases are supported through RocketSolver:

  • ROCKET_IAC - Infinite-area-chamber approximation (IAC): Isentropic combustion process.

  • ROCKET_FAC - Finite-area-chamber approximation (FAC): Entropic combustion process.

These models allow for rapid estimation of propulsion performance, including the characteristic velocity (\(c^*\)), thrust coefficient (\(C_F\)), and specific impulse (\(I_{\text{sp}}\)), while accounting for chemical equilibrium, composition-dependent thermodynamics, and finite expansion effects.

Congratulations!#

Congratulations you have finished the Combustion Toolbox MATLAB tutorial! You should now be ready to begin using the Combustion Toolbox on your own (see the examples folder).