gunt ET 796 User manual

Experiment Instructions
ET 796 Gas Turbine Jet Engine

ET 796 GAS TURBINE JET ENGINE
i
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This manual must be kept by the unit.
Before operating the unit:
- Read this manual.
- All participants must be instructed on
handling of the unit and, where appropriate,
on the necessary safety precautions.
Version 0.1 Subject to technical alterations
Experiment Instructions
Last modification by: Dipl.-Ing. J.Boxhammer

ET 796 GAS TURBINE JET ENGINE
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Intended use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Structure of safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4 Ambient conditions for the operating and storage location . . . . . . . . 12
3 Description of the device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Design of the trainer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 Device design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3 Process schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.4 Components of the trainer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4.1 Gas turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4.2 Fuel system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.4.3 Starting and ignition system . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.4.4 Control elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5 Measurement data acquisition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.5.1 Program installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.5.2 Program operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.6 Setting up the gas turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.6.1 Checking the gas turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.6.2 Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.7 Operating the gas turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.7.1 Preparations for start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.7.2 Bleeding the fuel lines with the kerosene start system . . . . . 33
3.7.2.1 Switch ECU to 6V kerosene start mode. . . . . . . . . . . . . . . . 33
3.7.2.2 Bleeding the fuel supply to the engine: . . . . . . . . . . . . . . . . . 34
3.7.2.3 Bleeding the fuel supply to the kerosene start system: . . . . 35
3.7.2.4 Testing and adjusting the fuel pump power . . . . . . . . . . . . . 37

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3.7.3 Starting the gas turbine up . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.7.4 Operating the gas turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.7.5 Shutting down the gas turbine . . . . . . . . . . . . . . . . . . . . . . . 42
3.8 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.8.1 Glow plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.8.2 Servicing the gas turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.9 Faults and troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.10 Decommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4 Basic principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.1 The open gas turbine cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.1.1 Representation in the heat diagram . . . . . . . . . . . . . . . . . . . 49
4.1.2 Thermal efficiency (ideal) . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.1.3 Specific work capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.1.4 Representation in the p-v diagram . . . . . . . . . . . . . . . . . . . . 52
4.1.5 Gas turbine jet engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.1 Recording measurements and their subsequent evaluation . . . . . . . 55
5.1.1 Preparation for the experiment . . . . . . . . . . . . . . . . . . . . . . . 55
5.1.2 Conducting the experiment. . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.1.3 Measured values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.1.4 Analysis of the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.1.4.1 Air mass flow and fuel mass flow . . . . . . . . . . . . . . . . . . . . . 57
5.1.4.2 Other characteristics of the gas turbine . . . . . . . . . . . . . . . . 59
5.1.4.3 Representation of the measured data in diagrams. . . . . . . . 61
5.1.4.4 Determining the fuel-air ratio . . . . . . . . . . . . . . . . . . . . . . . . 66
6 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.1 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.2 List of abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.3 List of formula symbols and units . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.4 List of symbols in the process schematic . . . . . . . . . . . . . . . . . . . . . 73

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6.5 List of identification letters used in the process schematic . . . . . . . . 74
6.6 Tables and graphs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.7 Worksheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

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ET 796 GAS TURBINE JET ENGINE
1 Introduction 1
All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 08/2014
1 Introduction
The ET 796 trainer is used to demonstrate and
study the function and behaviour of a gas turbine
in the model scale. Gas turbine plants are used to
generate mechanical and electrical energy:
– Driving generators in power plants
– Driving compressors and pumps in oil and gas
extraction
– Propulsion of ships, locomotives and heavy
vehicles
– For aircraft propulsion with propeller and jet
engines
Gas turbines are always used where high concen-
tration of power, low weight and quick startup are
required. Unlike piston engines, being turboma-
chines they allow high material throughputs with
small dimensions. This means lightweight yet
powerful drives can be constructed.
Since the moving parts of a gas turbine only per-
form a rotary movement, with good balance it is
possible to achieve virtually vibration-free run-
ning. The loud noise emissions caused by the
high gas velocities and by contact with the atmos-
phere are a drawback.
Compared to steam turbines, gas turbines oper-
ate at higher temperatures but at lower pressures.
The high temperatures, especially in the area of
the gas turbine, require special heat-resistant
materials.
The gas turbine used in the trainer is a single-
shaft gas turbine. All components required for
operation of the system are compactly combined
in a mobile rack.
Fig. 1.1 J85-GE-17A turbojet engine
from General Electric
Fig. 1.2 JetCat gas turbine

ET 796 GAS TURBINE JET ENGINE
21 Introduction
The system has a simple construction and is
designed specifically for educational purposes.
The operation and display of all important process
parameters is summarised on a control panel.
The PC-based measurement data acquisition
with evaluation software allows online logging of
all relevant process variables and their graphical
representation.
Besides purely demonstrating the turbine's oper-
ational behaviour, it is also possible to undertake
qualitative studies such as determining the thrust
and other characteristics of the gas turbine.
Learning objectives / exercises
• Operating behaviour of a jet engine including
starting procedure
• Determining the specific thrust
• Determining the specific fuel consumption
• Determining the fuel-air ratio

ET 796 GAS TURBINE JET ENGINE
2 Safety 3
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2 Safety
2.1 Intended use
The unit is to be used only for teaching purposes.
2.2 Structure of safety instructions
The signal words DANGER, WARNING or
CAUTION indicate the probability and potential
severity of injury.
An additional symbol indicates the nature of the
hazard or a required action.
Signal word Explanation
Indicates a situation which, if not avoided, will result in
death or serious injury.
Indicates a situation which, if not avoided, may result in
death or serious injury.
Indicates a situation which, if not avoided, may result in
minor or moderately serious injury.
NOTICE
Indicates a situation which may result in damage to
equipment, or provides instructions on operation of
the equipment.
DANGER
WARNING
CAUTION

ET 796 GAS TURBINE JET ENGINE
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Symbol Explanation
Electrical voltage
Hazard area (general)
Hot surface
Wear ear defenders
No naked light
No smoking
Oxidizing
Flammable
Toxic
Notice

ET 796 GAS TURBINE JET ENGINE
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2.3 Safety instructions
The following instructions must be observed to
ensure safe and reliable operation of the device.
All persons concerned with the device, especially
students, must be familiarised with the safety
instructions.
The attached operating instructions for the model
gas turbine must be carefully observed. Gas tur-
bines are delicate and sensitive machines even in
the model scale. Incorrect use or careless mainte-
nance can quickly destroy the gas turbine. There-
fore the operating instructions should be studied
carefully before the initial commissioning.
If any doubts arise, check with the manufacturer.
No liability can be accepted for damages resulting
from incorrect use.
WARNING
Electrical connections are exposed when the
control cabinet is open.
Risk of electrical shock.
• Before opening the control cabinet: Pull the
plug out.
• All work must be performed by trained electri-
cians only.
• Protect the control cabinet from moisture.

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WARNING
The gas turbine housing, exhaust stack and
any of the gas turbine's exhaust ducts
become very hot during operation.
Risk of burns.
• Do not touch any parts
• Leave parts to cool down
WARNING
Exhaust jet is very hot (200...300°C).
Risk of burns.
• The area of the exhaust jet must be free of per-
sons.
• Cordon off outlet area when operating as a jet
engine without exhaust gas outlet routing.
WARNING
Noise emissions > 130dB(A).
Risk of hearing damage.
• Wear suitable ear defenders.

ET 796 GAS TURBINE JET ENGINE
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WARNING
It should always be ensured that nobody is
present in the gas turbine's operating plane
when the turbine is operating.
Danger area.
• Either stand in front of or behind the gas tur-
bine, but not to the side of it.
• Comply with the following minimum safety dis-
tances for a gas turbine model.
In front of the gas turbine: 1.0 m
To the side of the gas turbine: 12.0 m
Behind the gas turbine: 10.0 m
WARNING
Strong blow out force at the fan outlet. Loose
objects sucked in can be ejected at high speed.
• Before switching on: Ensure that there are no
loose items present in or behind the device.
WARNING
In the event of a jet fuel leakage, do not use an
open flame and avoid sparks.
Risk of fire.
• Do not switch any electrical consumers on or
off.
• Check the system for leaking fuel lines before
use.
• Wipe up spilled jet fuel. Note that cloths soaked
in jet fuel are a risk of spontaneous combustion
(ventilate well).

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WARNING
Do not allow any combustible materials to
come into contact with the hot exhaust pipe or
to get into the exhaust jet.
Risk of fire.
• A wide zone around the outlet area must be
kept free of combustible or heat-sensitive
materials.
• Minimum distance to combustible materials in
the direction of the exhaust gas stream: 4 m
WARNING
In the event of fuel leaks in the gas turbine, jet
fuel can ignite on the hot turbine housing.
Risk of fire.
• System must not be operated if fuel is leaking.
WARNING
Exhaust gases contain odourless carbon
dioxide and carbon monoxide. There is a risk
of suffocation or poisoning.
Carbon dioxide can suffocate and carbon monox-
ide can poison.
• Never operate the gas turbine without an
exhaust pipe.
• The exhaust pipe must lead outside under all
circumstances.
• Ensure adequate ventilation.

ET 796 GAS TURBINE JET ENGINE
2 Safety 9
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WARNING
Smoking or open flames when handling com-
bustible fuels can lead to explosion or defla-
gration.
Possibility of severe injuries.
• No open flame
• No smoking
• Erect warning sign
• Comply with relevant statutory provisions when
transporting and storing fuels (kerosene, petro-
leum, etc.).
WARNING
Fire hazard due to overheating of the gas tur-
bine.
The strong suction effect at the air inlet can cause
loose objects such as paper, cleaning cloths or
parts of clothing to be caught up by the air flow to
the air inlet opening during operation. This can
clog the intake screen and cause overheating and
fire in the gas turbine.
• Only operate the gas turbine with the safety
guard mounted.
• Do not store loose items where they can be
sucked in by the gas turbine.
• Do not operate the gas turbine unattended.

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WARNING
When handling fuel, drops of fuel could get
into the eyes.
Risk of injury to the eyes.
• Wear safety goggles
If fuel gets into the eyes:
• Rinse eyes immediately
• Seek immediate medical attention
NOTICE
Gas turbine must not draw in foreign bodies or
dust.
Dust is deposited in the turbine bearings and
destroys them. The intake area must be kept free
of loose objects.
NOTICE
A suitable fire extinguisher must be kept near the
unit during operation.
NOTICE
The system may not be operated unattended.
NOTICE
Only operate gas turbine with a mixture of turbine
oil and pure kerosene or petroleum. Unsuitable
fuel may cause overheating or residue formation.

ET 796 GAS TURBINE JET ENGINE
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NOTICE
Fuel must be mixed with turbine oil to lubricate the
turbine bearings.
Only use suitable synthetic oils as specified in the
appendix.
NOTICE
The gas turbine must be overhauled every 50
operating hours. This work must be carried out by
the gas turbine manufacturer JET-CAT.
NOTICE
If critical operating conditions (overspeed, excess
temperature, leaks, etc.) occur, always switch the
operating mode switch to "off" before doing any-
thing else.
NOTICE
The system is not suitable for outdoor use. The
system must be operated in dry, dust-free and
well ventilated rooms. In particular, good ventila-
tion must be ensured, since the system requires
over 800m3/h of air.
NOTICE
The gas turbine is designed to be electrically insu-
lated on the thrust measuring table. There is a
potential of +12V at the gas turbine housing. It is
important to ensure that no electrically conductive
connection between the gas turbine and table is
established.

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2.4 Ambient conditions for the operating and storage location
• Enclosed space
• Free from dirt and humidity
• Level and fixed surface