A modular MATLAB-based framework for solving combustion and high-speed flow problems, with integrated support for caloric models, turbulence diagnostics, and spectral analysis.

Robust modular kernel

Robust, object-oriented, and fast chemical equilibrium computations.

Interactive App

The code is encapsulated in a user-friendly GUI with tons of capabilities.

Open source

Completely open source, GUI included!
GitHub GPLv3

Combustion Toolbox in action

 

The Combustion Toolbox [Cuadra et al., 2024] is a MATLAB-based thermochemical framework designed to solve problems involving chemical equilibrium for both gas- and condensed-phase species. The toolbox is composed of several modules, each of which is designed to solve a specific class of problems:

• CT-EQUIL computes the equilibrium composition of multi-component gas mixtures undergoing thermochemical transformations. The final equilibrium state is determined by a predefined set of chemical species (gaseous—including ions—or condensed phases) and two thermodynamic state functions, such as enthalpy and pressure, e.g., for isobaric combustion processes.

• CT-SD solves steady-state shock and detonation wave problems for both normal and oblique incidence.

• CT-ROCKET estimates the theoretical performance of rocket engines under highly idealized conditions.

• CT-TURBULENCE performs detailed analyses of turbulent flows, including turbulent statistics computations, Helmholtz decomposition, and spectral analyses.

The framework also includes an intuitive graphical user interface (GUI), with a royalty-free standalone version available for Windows, macOS, and Linux.

There is a fifth closed-source (i.e., proprietary) module, CT-EXPLO, that estimates the theoretical properties of high explosive mixtures and multi-component propellants with non-ideal EoS. Although still under development, CT-EXPLO is distributed in its current form as the thermochemical module of SimEx [Sánchez-Monreal et al., 2022] subject to a proprietary license. Further details on this module will be provided elsewhere.

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Tutorials

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Examples

See how the toolbox can be used in practical scenarios.

API Documentation

Let’s check the documentation of almost (every) functions.

Gallery

Here we show some results obtained using the Combustion Toolbox.

Figure 1: Variation of the molar fractions \(X_j\) for a TP transformation of a Silica-Phenolic mixture at atmospheric pressure \((p = 1\) atm\()\) with \(T \in [200, 5000]\); line: numerical results obtained with CT; symbols: numerical results obtained with NASA’s CEA [Gordon and McBride, 1994].

Figure 2: Hugoniot curves for different molecular gases at pre-shock temperature \(T_1 = 300\) K and pressure \(p_{1} = 1\) atm [numerical results obtained with Combustion Toolbox (lines) and contrasted with NASA’s Chemical Equilibrium with Applications (CEA) code [Gordon and McBride, 1994] excluding ionization (symbols)].

Figure 3: Variation of molar fraction for a CJ detonation for lean to rich CH4-air mixtures at standard conditions \((T_1 = 300\) K and pressure \(p_1 = 1\) atm\()\); line: numerical results obtained with Combustion Toolbox; circles: NASA’s Chemical Equilibrium with Applications code [Gordon and McBride, 1994]. The computational time was of 6.68 seconds using a Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz for a set of 26 species considered and a total of 351 case studies.

Figure 4: Pressure-deflection (a) and wave angle-deflection (b) shock polar diagrams for air (79% N2, 21% O2) at pre-shock temperature \(T_1 = 300\) K and pressure \(p_1 = 1\) atm, and a range of pre-shock Mach numbers M1 between 2 and 14; line: calorically imperfect gas with ionization/dissociation; dashed: calorically imperfect gas with frozen chemistry; circles: results obtained with Cantera [Goodwin et al., 2021] within Caltech’s SD-Toolbox [Browne et al., 2008, Browne et al., 2008]; diamonds: maximum deflection angle \(\theta_{\rm max}\).