rubberized_turbofan.py

class openconcept.propulsion.rubberized_turbofan.RubberizedTurbofan(**kwargs)

Bases: Group

Optimized N+3 GTF engine deck (can optionally be switched to CFM56) generated as a surrogate of pyCycle data. This version adds the rated thrust input which adds a multiplier on thrust and fuel flow to enable continuous scaling of the engine power.

This version of the engine can also be converted to hydrogen with the hydrogen option. It will scale the fuel flow by the ratio of LHV between jet fuel and hydrogen to deliver the same energy to the engine. This maintains the same thrust-specific energy consumption.

NOTE: The CFM56 and N3 engine models only include data Mach 0.2 to 0.8

and up to 35,000 ft. Outside that range, the model is unreliable.

Inputs:

  • throttle (float) – Engine throttle. Controls power and fuel flow. Produces 100% of rated power at throttle = 1. Should be in range 0 to 1 or slightly above 1. (vector, dimensionless)

  • fltcond|h (float) – Altitude (vector, dimensionless)

  • fltcond|M (float) – Mach number (vector, dimensionless)

  • ac|propulsion|engine|rating (float) – Desired thrust rating (sea level static) of each engine; the CFM56 thrust and fuel flow are scaled by this value divided by 27,300, while the N+3 thrust and fuel flow are scaled by this value divided by 28,620 (scalar, lbf)

Outputs:

  • thrust (float) – Thrust developed by the engine (vector, lbf)

  • fuel_flow (float) – Fuel flow consumed (vector, lbm/s)

  • surge_margin or T4 (float) – Surge margin if engine is “N3” or T4 if engine is “CFM56” (vector, percent)

Options:

  • num_nodes (int) – Number of analysis points to run (sets vec length; default 1)

  • hydrogen (bool) – True to convert fuel_flow to an equivalent fuel flow of hydrogen by multiplying by the ratio of lower heating value between jet fuel and hydrogen. Otherwise it will keep the fuel flow from the jet fuel-powered version of the engine deck, by default False

  • engine (str) – Engine deck to use, valid options are “N3” and “CFM56”, by default “N3”