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Turbofan Engine System

Implement first-order representation of turbofan engine with controller

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  • Turbofan Engine System block

Libraries:
Aerospace Blockset / Propulsion

Description

The Turbofan Engine System block computes the thrust and the fuel mass flow rate of a turbofan engine and controller at a specific throttle position, Mach number, and altitude. For more information on this system, see Algorithms.

The Turbofan Engine System block icon displays the input and output units selected from the Units parameter.

Limitations

  • The atmosphere is at standard day conditions and an ideal gas.

  • The Mach number is limited to less than 1.0.

  • This engine system is for approximation only and is not meant to be used as an engine-specific high-fidelity model. The engine system might not be scalable to large engine sizes.

  • This engine system is assumed to have a high bypass ratio.

Ports

Input

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Throttle position, specified as a scalar or vector. This value can vary from zero to one, corresponding to no and full throttle.

Data Types: double

Mach number, specified as a scalar.

Data Types: double

Altitude, specified as scalar or vector, in the units specified in the Units parameter.

Data Types: double

Initial thrust, specified as a scalar or vector, in the units specified in the Units parameter.

Dependencies

To enable this port, set Initial thrust source to External.

Data Types: double

Output

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Thrust, returned as a scalar or vector, in the units specified in the Units parameter.

Data Types: double

Fuel flow, returned as scalar or vector, in the units specified in the Units parameter units per second.

Data Types: double

Parameters

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Input and output units, specified as:

UnitsAltitudeThrustFuel Flow
Metric (MKS) MetersNewtonsKilograms per second
English FeetPound forcePound mass per second

Programmatic Use

Block Parameter: units
Type: character vector
Values: 'Metric (MKS)' | 'English'
Default: 'Metric (MKS)'

Initial thrust, specified as:

Internal

Use the value of the Initial thrust parameter.

External

Use external input for initial thrust value.

Programmatic Use

Block Parameter: ic_source
Type: character vector
Values: 'Internal' | 'External'
Default: 'Internal'

Initial thrust value, specified as a double scalar.

Programmatic Use

Block Parameter: IC
Type: character vector
Values: double scalar
Default: '0'

Maximum thrust at sea-level, specified as a double scalar, at a Mach value of 0.

Programmatic Use

Block Parameter: Fmax
Type: character vector
Values: double scalar
Default: '45000'

Fastest engine time at sea level, specified as a double scalar.

Programmatic Use

Block Parameter: tau
Type: character vector
Values: double scalar
Default: '1'

Thrust-specific fuel consumption at sea level, specified as a double scalar, in specified mass units per hour per specified thrust units, at:

  • Mach value of 0

  • Maximum thrust

Programmatic Use

Block Parameter: SFC
Type: character vector
Values: double scalar
Default: '0.35'

Coefficient representing the loss in thrust due to engine installation, specified as a double value.

Programmatic Use

Block Parameter: Nt
Type: character vector
Values: double scalar
Default: '0.9'

Algorithms

This system is represented by a first-order system with unitless heuristic lookup tables for thrust, thrust specific fuel consumption (TSFC), and the engine time constant. For the lookup table data, thrust is a function of throttle position and the Mach number, TSFC is a function of thrust and the Mach number, and engine time constant is a function of thrust. The unitless lookup table outputs are corrected for altitude using the relative pressure ratio δ and relative temperature ratio θ, and scaled by maximum sea level static thrust, the fastest engine time constant at the sea level static, sea level static thrust specific fuel consumption, and the ratio of installed thrust to uninstalled thrust.

References

[1] Aeronautical Vestpocket Handbook, United Technologies Pratt & Whitney, August, 1986.

[2] Raymer, D. P., Aircraft Design: A Conceptual Approach, AIAA Education Series, Washington, DC, 1989.

[3] Hill, P. G., and C. R. Peterson, Mechanics and Thermodynamics of Propulsion, Addison-Wesley Publishing Company, Reading, Massachusetts, 1970.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a