Turbofan Engine System

Implement first-order representation of turbofan engine with controller

• Library:

• Aerospace Blockset / Propulsion

• 

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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 indication purposes only. It is not meant to be used as a reference model.

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

Ports

Input

Throttle position — Throttle position

scalar | vector

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 — Mach number

scalar

Mach number, specified as a scalar.

Data Types: double

Altitude — Altitude

scalar | vector

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

Data Types: double

Initial thrust — Initial thrust

scalar | vector

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

Thrust — Thrust

scalar | vector

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

Data Types: double

Fuel flow — Fuel flow

scalar | vector

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

Data Types: double

Parameters

Units — Input and output units

Metric (MKS) (default) | English

Input and output units, specified as:

Units	Altitude	Thrust	Fuel Flow
Metric (MKS)	Meters	Newtons	Kilograms per second
English	Feet	Pound force	Pound mass per second

Programmatic Use

Block Parameter: units

Type: character vector

Values: 'Metric (MKS)' | 'English'

Default: 'Metric (MKS)'

Initial thrust source — Initial thrust source

Internal (default) | External

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 — Initial

0 (default) | scalar

Initial thrust value, specified as a double scalar.

Programmatic Use

Block Parameter: IC

Type: character vector

Values: double scalar

Default: '0'

Maximum sea-level static thrust — Maximum thrust at sea-level

45000 (default) | scalar

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 constant at sea-level static (sec) — Fastest engine time at sea level

1 (default) | scalar

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

Programmatic Use

Block Parameter: tau

Type: character vector

Values: double scalar

Default: '1'

Sea-level static thrust specific fuel consumption — Thrust-specific fuel consumption at sea level

0.35 (default) | scalar

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'

Ratio of installed thrust to uninstalled thrust — Coefficient representing loss

0.9 (default) | scalar

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™.

Introduced before R2006a