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ABSTRACT
The main aim behind this project is to design a test facility for the effective performance
of the Auxiliary Power Unit. This test bed is to be designed keeping in mind the parameters and
norms of effective quality assurance and reusability with zero maintenance. The test bed is to be
designed in such a way that it is user friendly when it comes to engine handling. The test rig has
to go through a stress analysis process in order to ensure that the structure is not affected and can
withstand prolonged engine usage for endurance testing purposes. This report contains the detail
analysis of the systems used in test facility and the problems faced during the designing of the
test bed in a design facility.
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INDEX
INTRODUCTION OBJECTIVE OF THE STUDY METHODOLOGY OF THE STUDY STATEMENT OF THE PROBLEM FINAL RESULT
CONCLUSION
SCOPE OF FUTURE STUDY BIODATA BIBLOGPAHY AND REFERENCES
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1. INTRODUCTION
Description of Test Component for Testing:
Auxiliary Power unit (APU):- The main purpose of an aircraft APU is to normally fulfil
several functions of the aircraft namely:
Main engine starting. Supply of cooling air for aircraft secondary systems, particularly when at ground idle
in hot climates.
Supply of electrical power when main engines are shut down, including for groundcheckout of aircraft systems.
These functions give an aircraft a self sufficiency when on the ground. In addition an
APU will be required to fire up at altitude in case of main engine flame out, to power
electrical systemsvital for fly by wire aircraftsand if at low flight mach nos. to
provide crank assistance to help restart the engines.
For civil applications APU requirements may include operations in all regions of flight
envelope, and for military aircrafts advanced systems with start times as low as a second.
A current typical start time is around 6 seconds at 15000 meters.
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The main requirements for the APUs have been
Low development and unit costs High reliability and maintainability. Low volume and weight Good specific fuel consumption.
APUs for aircrafts are generally exclusively simple cycle gas turbines. Fuel consumption of
APU is the secondary issue where operation is intermittent. Generally the output power range of
the APU is between 10 kW and 300kW.
The advantages of having an APU in an aircraft can be
Main engine starting. Supply of cooling air for aircraft secondary systems, particularly when at ground, idle in
hot climates.
Supply of electrical power when main engines are shut down, including for groundcheckout of aircraft systems.
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2. OBJECTIVE OF THE PROJECT
Personal objective:
To obtain practical knowledge on test facilities of APU and successfully complete the final year
project.
The objective of the project is:
1. To design a test facility for mounting and testing of an Auxiliary Power Unit.2. To understand the main functions of an APU.3. To measure the parameters regarding the operation of APU4. To analyse the primary and secondary systems needed in the test bed for working on the
APU engine.
5. To provide a detuner design for reducing acoustic levels of the noise produced by theexhaust gases of the detuner while working.
6. To study about the engine handling procedure.
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3. METHODOLOGY OF DESIGN
The auxiliary power unit is an optimum weighted engine. The engine weighs approximately 65
Kg which is optimum for being the weight of an APU of a medium scale aircraft. The APU is to
be mounted on a test frame where the various performance tests.
The test frame that is to be designed should meet the following criteria:
The connections from the frame to the engine mounting points should be calculatedperfectly so that there is zero clearance.
It should be stable (should not wobble while engine operation). It should be of an optimum height for easy handling and rigging of the APU. It should provide ample room for the engineer to easily mount the engine and join the
necessary connections and wires (fuel, electrical and control systems ).
It should not be made with less but robust material. The sectional joints should be able to withstand normal vibrations and forces due to
moment caused by the APU functioning.
It should meet all the safety standards and should be safe for operation.The test frame that is to be designed is manufactured of mild steel material. The material ensures
extra structural stability and robustness to the test frame design. Additional care is given for the
test frame to be resistant to engine vibrations and moment. The test frame is made of hollow
beams of 4mm thickness as per the design parameters and structural analysis. Below we are
about to discuss the steps that were performed while designing the test frame and the reasons for
selecting that particular design. The design that is done using a design software, in this case that
is Autodesk Inventor professional 2012. This is the latest software released by Autodesk
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company which has got many new features apart from the traditional features that has already
been there since the first version of the software release. The constraining features of the
software made it easier to choose for the project.
Step 1: Study of existing designs.Step 1 includes creating a sketch for reference while using the design software. A
thorough study of some existing designs of test beds was done before creating a free hand
sketch of the design. Subsequently it was constructed on scaled parameters.
A little modification was done to the existing designs and the new model was sketched.
Step 2: Sketching using Inventor software.Individual parts of the test frame were required to be sketched separately and then
extruded as per the requirements and the design specifications. Parts that were designed
using the software are discussed below:
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1) Ground plate
The ground plate is that section of the test bed that is bolted to the ground foundation.
The slots are designed as per the requirement of the test bed. The length of the base
plate is 1775mm and width is 220mm. The slot that is made is of radius 10mm and
length 40mm.
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3) Base frame:
As mentioned before , the base frame is a very important part of the test frame. Basically
it is the place where the pillars and the mounting frame along with the base plate on
which the mounting frame rests , are assembled. The base frame is of 2880mm X
1490mm dimension and of 75mm thickness. The slots on which the mounting frame is
to be placed is designed at 1081mm distance from and 398mm distance from each other.
This helps the mounting frame to rest on the base plate.
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4) Base plate (mounting frame mate):
The base plate is the mate of the mounting frame and the base frame. Both the structures are
assembled and joined at the constrained part of the assembly.
The base plate has four holes with threads of standard m12 bolts. The base plate is to be welded
with the mounting frame so that it joins to the base of the mounting frame. After that the base
plate is required to be bolted to the base frame so that the mounting frame rests on the base
frame. Standard m12 bolts are available for usage in the industries. One of the nuts drawing is
given below.
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An altogether of 16 nuts and bolts is used to fix the mounting frame with the base frame.
5) Mounting frame:a. Mounting frame 1 :
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The frame that is shown above is the initial prototype of the test frame on which the
engine is to be mounted. The design is robust as it has got a truss structure in it and is
stiffened by an slanting support at an angle 20 degrees at its back. The slant stiffener
is responsible for balancing the counter force produced by the APU while
functioning. The slant section but creates a problem for engine handling . in addition
the cross section on the frame increases problem in engine handling and rigging
process. The design also demands the usage of extra material (MS).
The height of the side mounting point is located at 800mm from the base of the frame
and the height of the top edge is 1100mm from the base. The distance of the base
stands is 400mmX400mm from each other.
Advantage of this design:
1. The frame is very stable and will be subjected to know bending moment orstructural failure due to engine operation.
Disadvantage of this design:
1.The design will use more material.2.The design may wobble due to vibrations caused by the APU.Hence it was required to review the design and re-create a design that meets all these
needs and leaves no disadvantages.
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b. Mounting frame 2:
The reviewed mounting frame has the same outer structure as the previous prototype.
However in this frame the structure is a little modified. The truss or the X shaped
stiffeners have been lowered in height to prevent the frame from wobbling. The
presence of the truss at the lower end ensures that the frame is stable but at the same
time ensures that there is no problem in engine handling.
The stiffeners are at a height of 360mm from base and apart from that there are no
additional changes as such.
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c. Mounting frame 3:
After reviews and modifications, a third mounting frame was designed keeping in mind all the
problems and corrections made. The new mounting frame becomes efficient in engine handing as
there is no obstruction between the engineer and the engine while rigging the engine. At the
same time the engine was to be mounted on a rigid and stable frame. In return to that, this design
gave the structure a stability and shape that is best augmented towards its use for the testing of
the APU.
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6) Assembly 1 : Includes the base plate , pillars and the base frame :
The base frame is comprised of ground plate, pillars & base frame. The ground plate is bolted
into the ground via slot provided At the edges. The pillars are welded onto the ground plate. The
pillars are placed at a distance of 80mm from the front & back. The side clearance is 10mm for
pillars from the ground plate. The base frame is welded onto the pillars.The entire base frame
rests on 4 sets of pillars & ground plates, calculated in such a way that proper clearance for
bolting of frame onto the base frame is ensured.
The base frame assembly forms the main supporting structure for the test frame design.The base
frame structure provides the necessary groun support for the entire test facility.
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Assembly 2 without engine:
Proposed design 1:
This frame assembly was 1st
achieved with the help of precise calculations & merging of frame
base plates with the markings onto the base frame. The frame base plates are welded onto the
frame legs. The bolting is done using M12 bolts & nuts. Bolting provides the necessary rigidity
to the test frame structure. The frame structure above was designed with stiffeners at 1/3rd
height
from the frame base & at the side to provide extra thickness.
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However it was realise that it was not require & also that it could prove as an obstacle during
engine handling which is not desired.The frame structure has mounting plates fixed to it as per
the dimensions of the mounting points onto the engine which are predetermined. The main aim
of the test frame design is to accurately calculate the mounting plate location w.r.t. the engine
mounting points in order to ease the mounting in such a way that the engine is statically stable
during mounting & testing.
The frame is designed in such a way that the engine axis is at the height of 1375mm (550mm
base frame assembly + 825mm mounting point at the axis), ie.4.51 feet from the ground level.
This provides ease in engine handling during testing. There is also 4 stiffeners from the sides of
the mounting frame so that the stability is maintained and uniform.
Advantages:
1. It has more structural stability than the first design and also gives a lot ofclearance for engine handling.
Disadvantages :
1. It has got a little space in the bottom for the engine rigging and de-riggingprocess.
2. The design uses more material in this case mild steel which is not economical.
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b. proposed design 2:
The test frame structure above was the modified version of the frame. It has the same dimensions
of the earlier mentioned base frame & frame bolting assembly as the above. However, the engine
specifications did not require extra stiffeners at 1/3rd
height. So the stiffeners at the centre were
removed & only the stiffeners onto the side were kept.
This design will ensure ease in engine handling which is desirable during rigging & de-rigging
process of engine testing. The test bed with the engine from different projections:-
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The above design shows the engine mounting onto the desired frame.
It can be visible clearly the ease with which the engine mounting & handling can be carried out
with the above frame design.
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The above diagram shows the rejected design of the test-frame.
The central stiffeners added to the load and could also possibly hinder the engine
handling process.
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METHOD FOR HANDLING A GAS TURBINE ENGINE DURING
PACKAGING
The method given here is used for handing a gas turbine engine during packaging. The method
comprises receiving the engine at a handling apparatus pivotally secured to the floor, removably
connecting the engine to the handling apparatus, pivoting the engine while supported on the
handling apparatus, lowering the engine into a container, and then removably connecting the
engine to the container.
BACKGROUND
Oftentimes, small gas turbine engines are individually put in containers at a manufacturing or
maintenance plant before being shipped elsewhere or stored. The gas turbine engines are moved
within the plant on engine transport devices. They are then transferred to a fixed structure
sometimes referred to as a shipping post. The shipping post holds the engine while one or
more technicians perform some tasks on the engine. This procedure, however, often require
numerous transfers from the shipping post to other supporting devices in order for the various
packaging tasks to be accomplished. These transfers are time-consuming and accordingly, often
result in a loss of productivity. Room for improvements exists.
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CLAIMS
1. A method for handling a gas turbine engine during packaging, the method comprising:
A. Receiving the engine at a handling apparatus having a post pivotally secured to the floor for
rotation about a generally vertical axis fixed with respect to the ground;
B. Rigidly connecting the engine to a support fixed to the post in rotation along, the vertical axis
of the handling apparatus, away from a container;
C. Pivoting the engine while supported on the handling apparatus by pivoting the post of the
handling apparatus about the vertical axis fixed with respect to the ground until the engine is in
vertical register with the container;
D. Lowering the engine into the container by translating the support in the handling apparatus;
and then removably connecting the engine to the container.
2. The method as defined in claim A, further comprising: disconnecting the engine from an
engine transport device after removably connecting the engine to the handling apparatus.
3. The method as defined in claim A, further comprising raising at least once the engine with
reference to the floor using the support of the handling apparatus.
4. The method as defined in claim A, further comprising: disconnecting the engine from the
handling apparatus after having removably connected the engine to the container.
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5. A method for handling a gas turbine engine prior from being set in a container, the method
comprising: rigidly connecting the engine to a support of a handling apparatus, the apparatus
having a post upon which the support is fixed in rotation along a vertical axis, the post being
rotatable around the substantially vertical axis fixed with respect to the ground, away from the
container, disconnecting the engine from a structure holding the engine immediately before the
handling apparatus; rotating the engine around the vertical axis of the apparatus fixed with
respect to the ground until the engine is in vertical register with the container; and then lowering
the engine into the container by translating the support along the handling apparatus.
6. The method as defined in claim 5, wherein the structure includes an engine transport system.
7. The method as defined in claim 5, wherein disconnecting the engine from the apparatus
includes removing the support from the engine.
8. The method as defined in claim 5, further comprising: raising at least once the engine with
reference to the floor using the handling apparatus.
9. The method as defined in claim 5, further comprising: removably connecting the engine to the
container.
10. A method of packaging a gas turbine engine into a container, the method comprising:
Receiving the engine at a handling apparatus having a post pivotally secured to the floorfor rotation about a generally vertical axis fixed with respect to the ground.
Rigidly connecting the engine to a support of the handling apparatus, away from thecontainer, the support being fixed to the post in rotation along the vertical axis.
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Performing at least one packaging task on the engine and raising the engine at least onceby translation of the support while the engine is continuously supported by the handling
apparatus.
Pivoting the engine while supported on the handling apparatus by pivoting the handlingapparatus about the vertical axis fixed with respect to the ground until the engine is in
vertical register with the container; and then transferring the engine directly into the
container.
11. The method as defined in claim 10, wherein transferring the engine into the container
includes removably connecting the engine to the container.
It should be noted that the word packaging is a generic word designating the various tasks
required to put an engine in a container, and may include the transfer of the engine from an
engine transport device to the handling apparatus. These tasks can include, for example, draining
fluids used in the engine during a bench test, installing plugs to cover openings, securing wires
together, etc. A wide range of other tasks can be done as well. Once in the container, the engine
can be, for instance, shipped elsewhere or stored while in the container. The engine in the
container can be a fully-assembled engine or an engine in which some parts will be assembled
later. Also, the word handling is a generic word designating the various steps of moving the
engine during packaging.
The apparatus has a base secured to the floor or to a similar solid structure. The base can be in
the form of a plate bolted to the floor. It holds a turntable having a substantially vertical pivot
axis. The turntable has one end secured to the base and other end that is attached to the bottom
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end of a substantially vertical post by means of a sleeve. The post is rotatable around the vertical
pivot axis. The apparatus also comprises a substantially horizontal side arm projecting from the
post. In the illustrated embodiment, the side arm projects from the upper end of the post. The
connection between the post and the side arm can be made in a number of ways. In the illustrated
example, the connection includes a sleeve rigidly attached over the upper end of the post. The
side arm is welded or otherwise attached to the sleeve.
A hoist is provided on the side arm. The hoist can include, for instance, a pneumatic motor
mechanically connected to a reel supporting a chain or a sling.
Gas turbine engines often have two opposite integrated side plates by which the engine can be
connected to another structure. The handling apparatus comprises a rigid side support having one
end in sliding engagement with the post and an opposite end that can be removably connected to
one of the side plates of the engine through an engine mount. The support is said to be rigid,
which means that the support is normally rigidly holding the engine in the same position. This
facilitates the tasks of the technician or technicians. This does not exclude the possibility of
having an adjustable support in which the orientation of the engine can be changed in accordance
with one or more degrees of freedom. The connection of the side support with the post can
include a flange or another element that is operatively connected to the post . In the illustrated
example, the flange of the side support is slid ably connected to a vertically-extending slot (not
shown) on the side of the post. The slot, the side arm and the support are in registry with each
other. The support is held by the sling of the hoist , which sling has a free end attached to a hook
or a hole provided on the support .
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If desired, the post can be provided with a plurality of spaced-apart horizontal holes crossing the
vertically-extending slot on the post . One or more pins can then be inserted below the
support to prevent the engine when one is connected to the support , from falling towards the
floor in case of a failure of the hoist or any of the parts to which it is connected.
A brake can be used next to the base to prevent the turntable , and thus all the other elements
connected thereto, from rotating when that is not required. In the illustrated example, the
brake includes an actuator with a piston having an end engaging the bottom side of a disk on the
pivotal side of the turntable. The actuator of the brake can be electric, pneumatic, hydraulic, etc.
The above description is meant to be exemplary only, and one skilled in the art will recognize
that changes can be made to what is described above without departing from the scope of the
appended claims. For example, the hoist can be manually powered or powered using an electric
or hydraulic motor. The hoist motor, if any, and its reel do not necessarily need to be provided on
a side arm. It can be provided on the post itself, for instance, and the sling or chain can then
reach the proper location on the side arm using one or more pulleys. Alternatively, the hoist can
be in the form of a screw inside the post and engaged to a follower designed to move the support
up or down. A side arm can then be omitted. The slot along the post and which receives the edge
of the support can be replaced by an equivalent system, such as a slot in the support and which
engages a vertical flange projecting on the side of the post, a carriage with rolls engaged around
the post, etc. The brake at the bottom of the apparatus can include pins or similar fasteners to be
inserted in corresponding holes so as to prevent the apparatus from rotating. Although it has been
suggested in the detailed description that the engine be connected inside the container before
disconnecting it from the support of the apparatus, thereby maintaining a constant attachment
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with a rigid structure at all time, it is possible to design the container so as to temporally support
the engine while it is disconnected from the support and prior to connecting it to the container.
Although the post is said to be vertical or substantially vertical, it can define a certain angle with
the vertical. Similarly, a side arm connected to the post must not necessarily be horizontal and
can define a certain angle with the horizontal. It is possible to have a portion of the support of the
apparatus being detachable from the rest of the apparatus. This way, the detachable portion can
remain with the engine in the container. The engine transport device may be different. Still other
modifications will be apparent to those skilled in the art, in light of a review of this disclosure,
and such modifications are intended to fall within the appended claims
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STATEMENT OF THE PROBLEMS
PROBLEMS THAT MAY BE ENCOUNTERED WHILE THE PROJECTWORK
The accepted design may fail the stress analysis test. Designing of the test bed has to be calculated according to the changing requirements. The values of the parameters may go beyond the tolerance limits due to faulty feedback
from the systems.
Problems encountered during the actual assembly process of the test facility. Detuner designing may be complicated due to noise levels and acoustic problems. Detuner designing may be complicated due to space available in the test bed. For the designing of detuner the selection of proper material so that it does not fail the
endurance parameters.
Detuner design may be complicated due to parameters of back pressure and hightemperature.
.
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FINAL RESULT
Post studying and analysing the project, it is concluded that all the designs and
modifications are as per the needed operational specifications for the auxiliary power unit. A
well planned and developed test facility is necessary for successful operation and working over
the APU engine.
The performance and testing of the auxiliary power unit depends upon the following factors
during operation:-
Mass Flow Rate of air Mass flow rate of fuel Exhaust Exhaust gas temperature Test bed structural stability Acoustic levels Control system
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Power output Performance rating Systems used while working Handling check and pass off settings Ease of operating
CONCLUSION
It will also help in planning and implementing of the layout of the test bed.
The layout will help in placing and adjusting the systems over the engine according to the space
available in the test bed room.
A qualitatively and quantitatively good test bed facility is necessary for the efficient and desired
working of the APUMain Gas Turbine Engine.
Building of an effective test facility which can be further used for testing of any APU Main
Gas Turbine Engine.
The test facility is well equipped to carry out all the performance tests to examine the
performance parameters expected from the APU.
The test bed should have various systems for the healthy working over the APU engine.
The proposed test bed facility is designed in such a way that it can be used in different extreme
weather conditions. As well the mounting assembly is made in such a manner that the APU
engine of any aircraft can be easily mounted on the frame.
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The control systems are well equipped so that the testing can be carried out smoothly and totally
controlled.
The designed detuners will reduce to noise levels considerably and substantially along with the
exit velocity and exit temperature of the exhaust gases.
BIBLOGRAPHY & REFERENCES
GAS TURBINE ENGINEWALSH AND FLECTHER AIRCRAFT PERFORMANCEJr. J D ANDERSON GAS TURBINECOHEN AND ROGERS WIKIPEDIA INTERNET SOURCE GOOGLE - SEARCH ENGINE AGARD SPECIFICATION OF TEST BED TRAINING NOTES FOR TEST BED - HAL