Turbofan Engine System (Aerospace Blockset)

Implement a first-order representation of a turbofan engine with controller

Library

Propulsion

Description

The Turbofan Engine System block computes the thrust and the weight of fuel flow of a turbofan engine and controller at a specific throttle position, Mach number, and altitude.

This system is represented by a first-order system with unitless heuristic lookup tables for thrust, thrust specific fuel consumption (TSFC), and engine time constant. For the lookup table data, thrust is a function of throttle position and Mach number, TSFC is a function of thrust and 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 and relative temperature ratio , and scaled by Ratio of installed thrust to uninstalled thrust, Maximum sea-level static thrust, Sea-level static thrust specific fuel consumption, and Fastest engine time constant at sea-level static.

The Turbofan Engine System block icon displays the input and output units selected from the Units pop-up menu.

Dialog Box

Units

Specifies the input and output units:


	Altitude	Thrust	Fuel Flow
`Metric`	Meters	Newtons	Kilograms per second
`English`	Feet	Pound force	Pound mass per second

Initial thrust source

Specifies the source of initial thrust:


`Internal`	Use initial thrust value from mask dialog.
`External`	Use external input for initial thrust value.

Initial thrust

Initial value for thrust.

Maximum sea-level static thrust

Maximum thrust at sea-level and at Mach = 0.

Fastest engine time constant at sea-level static

Sea-level static thrust specific fuel consumption

Thrust specific fuel consumption at sea-level, at Mach = 0, and at maximum thrust, in specified mass units per hour per specified thrust units.

Ratio of installed thrust to uninstalled thrust

Coefficient representing the loss in thrust due to engine installation.

Inputs and Outputs

The first input is throttle position. Throttle position can vary from zero to one, corresponding to no to full throttle.

The second input is Mach number.

The third input is altitude, in specified length units.

The first output is thrust, in specified force units.

The second output is fuel flow, in specified mass units per second.

Assumptions and Limitations

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

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.

References

"Aeronautical Vestpocket Handbook," United Technologies Pratt & Whitney, August, 1986.

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

Hill, P.G, and Peterson, C.R., "Mechanics and Thermodynamics of Propulsion," Addison-Wesley Publishing Company, Reading, MA, 1970.

Temperature Conversion Velocity Conversion