source_fuel
Specifies the parameters of a fuel source that emits properties into the simulation grid.
This should be connected to the additional_properties input on a source_air node.
Several source_fuel nodes can be connected to the additional_properties fan port to form more advanced mixtures of fuel and oxidizer. For example, a MAPP gas typically used for practical VFX consists of propyne, propadiene, propane, and in some cases also propylene and butane.
Inputs
General
enable_fuel_source
Enables this fuel source.
start_frame
The frame at which emission from the fuel source starts.
use_end_frame
Stops the emission at a certain frame. Otherwise emission will continue for the duration of the simulation.
end_frame
The frame at which emission from the source stops.
Fuel Properties
fuel_type
The type of fuel which can be selected from a drop-down menu. Only a single type of fuel can be specified with a specific source_fuel node, but several source_fuel nodes can be daisy-chained. This allows you to match real world footage if you know the type of fuel. Otherwise, leave this at the default and adjust other parameters to obtain the desired artistic results.
ignition_temperature
The temperature at which the fuel ignites in degrees Celsius. Below the ignition temperature, no combustion takes place. Note that each type of fuel has a real world ignition temperature, but it can be re-defined here for artistic purposes.
For a larger explosion blast, use a lower ignition temperature.
oxygen_percentage
The percentage of oxygen in the oxidizer. For example, if oxygen_percentage is set to 0.4, the oxidizer will consist of 40 percent oxygen and 60 percent nitrogen. Typically, if there's sufficient fuel, increasing oxygen_percentage will lead to more violent explosions, increased flame propagation speeds, and higher temperatures.
By default, the ambient surroundings contain air (predominantly nitrogen and oxygen), so fuel can burn even with an oxygen_percentage of 0 if there's sufficient oxygen diffusion into the fuel.
burn_rate
A value between 0 and 2 that defines the stoichiometry of the mixture of fuel and oxidizer. A value of 0 leads to a smoky flame and more specifically means that only fuel will be emitted. Values below 1 correspond to fuel-rich conditions where there will be excess fuel after the combustion process. Increasing values from 0 to 1 gradually transition the simulation from a smoky flame towards a cleaner but also more violent combustion. A value of 1 indicates perfect stoichiometric conditions, that is, all available oxygen and fuel will react to form by-products with no excess oxygen nor fuel. Values above 1 correspond to fuel-lean conditions where there will be excess oxygen after combustion.
Outputs
fuel_source
The output is an object that contains an aggregation of fuel source related inputs to the aero solver and should be connected to the sources port on a simulate_aero node or to the air_source port on a source_fuel node.