T-45 Thrust

Aero Chapter 05/06 (TS) and 05 (ADV & IUT), Thrust and Thrust Curve Review

T-45 Aerodynamics Student Workbook

consumption, and a lower specific weight. The turbojet came first because it was simpler technology.

The turbofan engine is preferred in most modern applications.

The afterburner is a section added to some jet engines, which can provide a large thrust increase with

little weight. The afterburner section consists of another set of fuel spray nozzles, flame holders behind

the turbines, and variable exhaust nozzles. Since there are no highly stressed engine components

(turbine blades) behind the afterburner, a large amount of fuel can be burned there. Afterburners are a

very inefficient use of the fuel; however, as fuel flow will typically triple or quadruple in afterburner

operation for a 50% increase in thrust.

T-45 THRUST

A single Rolls-Royce

Air

F405-RR-401

Combustion

turbofan engine that

and Exhaust

develops an

installed static sea

Turbines

level thrust of 5,527

Compressor Compressor

Bypass Duct

pounds provides

thrust in the T-45.

Combustion

Exhaust

Referring to Figure

Section

79, air enters the

engine directly at the

first stage of N1.

Between N1

components and N2

components (which

is typical of turbofan

engine design),

airflow is divided into

two paths, one of

Fan

which enters the N2

Bypass Duct

(Outboard)

compressor stage

and the other enters

Figure 79: T-45 TURBOFAN ENGINE

the annular bypass

duct. The airflow

from the N2 section then enters the combustion section where eighteen fuel spray nozzles provide fuel for

combustion. From the combustion section, the heated and accelerated airflow enters and flows through

the turbine section.

The N2 turbine turns the shaft, which drives the N2 compressor and engine accessory gearbox. The N1

turbine drives the N1 compressor (the engine fan) via the N1 shaft. There is no direct mechanical

connection between the N1 and N2 sections.

Airflow from the turbine section then moves into the exhaust section. The heated and accelerated airflow

is mixed with the airflow from the annular bypass duct. The mixed airflow then is discharged through a

fixed geometry, converging exhaust nozzle, the shape of which increases the thrust.

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