1

Mechanism Description of the Rolls Royce Trent 900

Smit Patel

Embry-Riddle Aeronautical University

2

Introduction

Intended Audience

This mechanism description is for those who have a working knowledge about Rolls Royce’s

Trent 900 turbofan engine. The ideal audience would be mechanical and aerospace engineers /

technicians.

Formal Definition

The Trent 900 engine is a three shaft high bypass ratio, axial flow, turbofan with Low Pressure,

Intermediate Pressure and High Pressure Compressors driven by separate turbines through

coaxial Shafts.

General Description

The Trent 900 is the fourth member of the Trent family and includes the latest proven

technology. The Trent 900 is the engine of choice for the Airbus A380, with two thirds of

operators selecting the engine. It delivers the lowest lifetime fuel burn and has excellent

environmental attributes. The Trent 900 will continue to deliver customer benefits as it is part of

a living engine family. The Trent 900 fleet now comprises 228 engines on 57 aircraft in service

and has accumulated over 2.5 million hours by August 2013.

The Trent 900 engine is a three shaft high bypass ratio, axial flow, turbofan with Low

Pressure, Intermediate

Pressure and High Pressure

Compressors driven by

separate turbines through

coaxial shafts. The LP

3

Compressor fan diameter is 2.95m with a swept fan blade and OGV’s to increase efficiency and

reduce noise. The combustion system consists of a single annular combustor. The LP and IP

assemblies rotate independently in an anti-clockwise direction; the HP assembly rotates

clockwise, when viewed from the rear of the engine.

Process Analysis

Firstly, air that is pulled in by the fan through the core of the engine is compressed by the

intermediate and high pressure compressor blades. After fuel injection and ignition the

expanding gas exits the engine through various sets of turbine blades. These blades are turned

(like the sails on a windmill) and, in turn, they rotate the fan and compressor blades at the front

via shafts that pass through the center of the engine. As such, it is the turbine blades that turn the

fan, which pulls the air through to develop the thrust. In reality only about a quarter of the air

pulled through the fan enters the core of the engine, the remaining cold air is thrown backwards,

and around the outside of the core to develop the majority of the engine’s thrust (see figure 2).

4

Overall Description

The overall length of the Trent 900 from tip of the spinner to the tail bearing housing plug mount

flange is 5477.5 (mm). The diameter around the center line is 3944 (mm). The engine weighs six

thousand two hundred forty six kilograms without any fluids.

The engine is made of four different types of materials, Aluminium, Titanium, Steel, and nickel

as you can see in the picture below.

In

order for the engine to start the minimum oil temperature cannot be lower than negative 30

degrees Celsius. If the temperature falls below that temperature the engine has to be started with

special procedure which is defined in the operating instructions. To operate the engine the fuel

temperature during flight could be no lower than minus fifty fours degrees Celsius or the

freezing point of that specific brand of fuel used. The fuel temperature could not exceed fifty five

degrees Celsius during climbing and fifth degrees when descending. The engine is designed to

withstand 34 kPA of absolute

The Fan, compressor, combuster , turbine are considered to be the main parts of the

5

engine. However the most important part of any engine is the fan as its job is to draw the air into

the engine which starts the whole process thus providing the plan with thrust.

6

Main Parts (A-level heading)

Fan system

Lightest fan system in the industry Proven swept fan design (116" diameter) - low noise, low

weight and high performance Proven light weight titanium fan case - robust and transportable

whole in Boeing 747F

Compressor

Intermediate and high pressure compressors

Proven Trent technology world-class performance

Lowest risk

Bladed discs throughout

lowest maintenance cost

Next generation 3D aerodynamics

More efficient airflow throughout engine

Better fuel consumption

Less parts and lower weight

Rolls-Royce unique 3-shaft design enables compressors to operate at optimum

speeds

Combustor

Proven Trent technology

Tiled combustor for lowest maintenance costs

Engine tests have confirmed the Trent 900 as havingthe world's lowest emissions

7

Meets all proposed legislations with margin Assuredasset value

Turbines

Proven Trent technology

Low risk

Next generation 3D aerodynamics with end wall profiling

optimum performance and lowest fuel burn

Proven shrouded turbine blades

Best performance retention

High pressure contra rotation

Conta-rotation

Contra-rotation of the high pressure system significantly improves the performance and

efficiency of the intermediate pressure turbine

Improved efficiency

Fewer parts

Lighter parts