1rafael mauricio uribe niÑo 20061171036 group number 4

8/9/2019 1RAFAEL MAURICIO URIBE NIÑO 20061171036 GROUP NUMBER 4

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2009

INDIVIDUAL FINAL REPORT

OPTIMIZATION AND DESIGN OF A

COMPRESSOR

SANBUENAVENTURA UNIVERSITY

FACULTY OF ENGINEERING

PROGRAM OF AERONAUTICS

BOGOTA



2

OPTIMIZATION AND DESIGN OF A COMPRESSOR

INDIVIDUAL FINAL REPORT

AERODYNAMICS ENGINEER

RAFAEL MAURICIO URIBE NIÑO

20061171036

PHD FERNANDO COLMENARES

CRANFIELD UNIVERSITY

SAN BUENAVENTURA UIVERSITY

FACULTY OF ENGINEERING

PROGRAM OF AERONAUTICSBOGOTA

2009



4

TABLE OF CONTENTS

NAME. PAG.

Introduction __________________________________________ 6

1. ABSTRAC__________________________________________ 7

2. Exposition of the problem ____________________________ 8

2.1 Precedents_____________________________ 8

2.2 Description and formulationof the problem__________________________ 9

2.3 Justification____________________________ 10

2.4 Aims________________________________________ 11

2.4.1 General aim___________________________ 11

2.4.2 Specific aims__________________________ 11

2.5 Scopes and limitations_________________________ 12

2.5.1 Scopes________________________________ 12

2.5.2 Limitations____________________________ 12

2.6 Methodology____________________________ 13

3. Theoretical investigation_______________________________ 14

3.1Basic turbojet – definition____________________ 14

3.2 Axial compressor – definition_________________ 15



5

3.3 Aerodynamics – definition___________________ 16

4. Aerodynamic theory__________________________________ 174.1 Velocity triangle_________________________ 17

4.2 Incidence angle__________________________ 19

4.3 Boundary layer__________________________ 20

5. Engineering development______________________________ 21

5.1 Generation of the airfoil __________________ 21

5.2. Generation of the mesh__________________ 24

5.3. Simulation in cfd-fluent__________________ 26

5.4 Results obtained_________________________ 32

6. Analysis of results ____________________________________ 39

6.1 Pressures_______________________________ 39

6.2 Velocities_______________________________ 39

7. Conclusions__________________________________________ 41

8. Future Work_________________________________________ 43

9. Bibliography_________________________________________ 44



6

INTRODUCTION

Across the years the human being has looked for the way of designing methods thatfacilitate the accomplishment of the different tasks that the daily life demands, is of this

form as the engineering has been present in the different evolutionary stages of the society

contributing solutions and creating facilities in the accomplishment of works.

The development of engineering is kept in the measure that designs and constructions,

empirical or real they develop across the time, the emergence of new tools or that allows the

optimization of the already existing ones is the dynamics that carries the development of the

society.

To contribute to the solution of such problems of engineering it is necessary to acquire

such skills as the explicit knowledge of the field that one is going to work, this needs that it

is investigated, analyze, argue and understand appropriately due to the fact that hereby

they take advantage of the diverse resources realizing effective procedures.

The present project has as aim realize an appropriate analysis of a turbo jet, in order that

with help of more sophisticated tools it could optimize the proposed information and obtainan appropriate design of the compressor, specifically, hereby give solution to the demand of

the client who is to reduce the specific fuel consumption S.F.C. It is for it that will carry

out the different steps in a design to culminate with the construction and proof of the

mechanism, in order to realize a project confronting all the real variables that in a future,

in the performance as engineers, we must confront.

The formless present contains the first steps of the investigation, bearing in mind that is

based on royal values of the current industry, in addition the respective analysis apologized

to the different demonstrations that help to find mistakes in the considerations of the

different systems in which the phenomena were studied. That for this case is the

aerodynamic phenomena that influence the design of the already renowned compressor.



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1. ABSTRAC

The following work contains a series of compilation of information and graphs of simulations that were done in order to explain a phenomenon that consists in to optimize an already existing component to develop capacities for the design for computer and the analysis of different factors, the following pages one is going to treat the topic of improving a component of the compressor to optimize the specific fuel consumption.



8

2. EXPOSITION OF THE PROBLEM

2.1 PRECEDENTS

The development of the present project has the advantage of presenting several national

precedents, inside San Buenaventura University. The process that is carried out has been

realized in repeated opportunities as documents of thesis in the different years, with

different or wider approaches.

The proofs that are near to the investigations researches that were named previously are the

documents realized by students of posterior semesters who leave us of general form a guide

on whom we can base our research also.

Besides the fact that also they possess a wide range of references of texts from which we can

extract a series of ideas that were helping us to carry out our project.



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2.2 DESCRIPTION AND FORMULATION OF THE PROBLEM

Which are the parameters and procedures that follow for the design and construction of acompressor to achieve a decrease of the specific fuel consumption?



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2.3 JUSTIFICATION

The present work is realized in order to acquire skills and aptitudes in the design and theconstruction of engines, is of great interest since, for the authors due to the fact that hereby

there is acquired innovative and own knowledge of the work camp, as well as also for future

students who are interested in these subject matters and across an excellent work they

could acquire a guide for the accomplishment of the own one.



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2.4 AIMS

2.4.1 GENERAL AIM

To effect the optimization and the preliminary design of all the stages of a

compressor to obtain a low specific consumption of fuel.

2.4.2 SPECIFIC AIMS

Know and to apply all the mathematical models who concern theaerodynamics of the blades of the compressor and in general the whole

compressor. Demonstrate that with changes in different physical phenomena during the

compression of the air in each of the stages of the compressor it is possible to

reduce the specific fuel consumption. Investigate fundamental factors of functioning in the current industry,

hereby to base the design on real applications to generate a useful projectthat contributes great knowledge and experience in the formation as

professionals.



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2.5 SCOPES AND LIMITATIONS

2.5.1 SCOPES

The maximum scope of the present project is that in the simulation in CFD of the

prototype. The results that throw the iterations are coherent with what we calculate.

2.5.2 LIMITATIONS ( The limitations these of the project given as for)

The interpretation of mathematical models depends on the author of the text, this

does difficultly to understand if we relate several texts between them. The theory that exists is not adapted in relation to which the students we do not

understand many of the terms named in the texts for it the comprehension and the

good understanding of the theory takes very much more time of the one that is had

planned.

Availability of equipments since they possess few areas of work for the simulation.

Rather the university does not possess the sufficient licenses of the program CFD in

order that we all could work calm. It does not exist a technical support that could give us support with doubts that we

have brings over of the program CFD.



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2.6 METHODOLOGY

To follow a correct methodology we must continue a few specific conditions, since it is togather the precise information that defines us since we are going to work from the

beginning, also to obtain all the mathematical models in order to realize all the pertinent

calculations for the due process of design, and finally to look for the tutorials of the

programs to working in order that in the moment to effect the simulations there could be

obtained the results that get accommodated more to the reality of the calculated previously



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3. THEORETICAL INVESTIGATION

3.1 BASIC TURBOJET – DEFINITION.

It is called basic turbo-jet, simple turbo-jet or pure turbo-jet, to the system motorcyclepropellent constituted by a gas generator with the attachment of a bulging tewel and acompressor, which canalizes and communicates a sensitively axial direction to the gasesproceeding from the generator.

The part engine of the basic turbo-jet is the gas generator; the organ propellent of thesystem is the turbine and the tewel, which transforms the work produced by the generatorin kinetic energy of the jet of exit .1

FIG 1. SCHEME OF A BASIC TURBO-JET

En:Image:FAA-8083-3A Fig 14-1.PNG

_________________________________________________________________________

1. OÑATE, Antonio Esteban. Turborreactores, teoría, sistemas y propulsión de aviones. Madrid, 1981.Pag62



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3.2 AXIAL COMPRESSOR – DEFINITION

The air in an axial compressor, flows in the direction of the axis of the compressor across aseries of mobile blades or blades of the rotor connected to the axis by means of a disc and aseries of fixed blades or blades of the stator connected to the chamber of the compressor andconcentric to the axis of rotation. Every set of mobile blades and fixed blades form a stage ofthe compressor.

The air is taken by the set of mobile blades and stimulated backward in sense axial anddedicated to the set of fixed blades with a major speed. The fixed blades or blades of thestator act as diffuser in every stage, transforming the kinetic energy of the air into potentialenergy in the shape of pressure and in turn, give to the flow the angle adapted to enter the

mobile blades of the following stage

Every stage of an axial compressor produces a small increase in the pressure of the air,values that rarely overcome relations of 1.1:1 to 1.2:1. A major increase of pressure in anaxial compressor is achieved installing several stages, appearing a reduction in thetransverse section as the air is compressed. 2

FIG 2. AXIAL COMPRESSOR

https://reader010.{domain}/reader010/html5/0530/5b0dd3f7c0466/5b0dd400b67e9.jpg

__________________________________________________________________

2. http://www.uamerica.edu.co/tutorial/4turgas_text3_1.htm



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3.3 AERODYNAMICS – DEFINITION

Aerodynamics is the way air moves around things. The rules of aerodynamics explain howan airplane is able to fly. Anything that moves through air reacts to aerodynamics. A rocket

blasting off the launch pad and a kite in the sky react to aerodynamics. Aerodynamics even

acts on cars, since air flows around cars

Aerodynamics is the study of forces and the resulting motion of objects through the air.

Judging from the story of Daedalus and Icarus, humans have been interested in

aerodynamics and flying for thousands of years, although flying in a heavier than air

machine has been possible only in the last hundred years. Aerodynamics affects the motion

of a large airliner, a model rocket, or a kite flying high overhead.



17

4. AERODYNAMIC THEORY

The most important thing and what it is necessary to bear more in mind for the study of theaerodynamics in the compressors and especially in the blades of every stage of the

compressor it is the velocity triangle.

4.1 VELOCITY TRIANGLE

Some of the most important topics in what it has to see with the study of the aerodynamics it is the

speed triangle since with this triangle and knowing the values of the absolute speed of the air, the

relative speed of the fluid with regard to the rotor of the compressor and the linear speed of the rotor

I can calculate all the factors that alter the efficiency of the blade of the compressor, as them it are:

- Aerodynamic load in the blade.

- Incident angle of the air.

- Press in the blade, and it allows me to determine in that moment is going to happen a source or in

that moment is going to arise a source.

FIG 3. VELOCITY TRIANGLE FOR A SINGLE STAGE



18

Assuming that C a = Ca1 = Ca2 two basic equations follow immediately from the geometry of

the velocity triangles. These are:

= tan + t an

= tan + t an

By considering the change in angular momentum of the air in passing through the rotor,

the following expression for the power input to the stage can be deduce:

= ( − )

Where and are the tangential components of fluid velocity before and after the

rotor. This expression can be put in terms of the axial velocity and air angles to give:

= (tan −tan )

It is more useful, however, to express the power in terms of the rotor blade air angles,

and . It can readily be seen that ( tan −tan ) = ( tan −tan ) . Thus thepower input is given by:

= ( tan −tan )

This input energy will be absorbed usefully in raising the pressure of the air and wastefully

in overcoming various frictional losses. But regardless of the losses, or in other words of the

efficiency of compression, the whole of this input will reveal itself as a rise in stagnation

temperature of the air. The stagnation temperature rise in the stage, ∆ is given by:

∆ = − = − = (tan −tan )



19

The pressure rise obtained will be strongly dependent on the efficiency of the compression

process, denoting the isentropic efficiency of the stage by , where:

= ( − )/ ( − ) , the stage pressure ratio then given by 3:

= = 1 + ∆ ( )

4.2 INCIDENCE ANGLE

The angle of incident is basic since this one incurs directly the relation of pressure of thecompressor and for that this also related on the cap borders of the blade.

For this there is looked that the diffuser is as efficient as possible in order that a high

pressure supports in the compressor a limited part of the diffuser.

FIG 4. BLADE SPACING AND VELOCITY DI STRIBUTION THROUGH PASSAGE

_______________________________________________________________________________

3. SARAVANAMUTTOO, Hih. Gas Turbine Theory. Edition 4.United Kingdom, 1996.Pag 158-159



20

4.3 BOUNDARY LAYER

The boundary layers they are the last caps of the fluid in this case the air that passes for a cap of

material of the blade, this cap can be laminate or turbulent depending on the speed of the same one

and of the form of the airfoil for this which passing.

For our case the boundary layer is studied to analyze the speed variation in the zone of contact

between a fluid and an obstacle that one finds in his bosom or for the one that move 4.

FIG 5 BEHAVI OR OF THE FLOWN WI TH DI FFERENT GEOM ETRIES

http://1.bp.blogspot.com/_QcPSRUCyrgg/R9CPGDpGu5I/AAAAAAAAA6Y/SGmh0ql9s74/s1600/585px-

________________________________________________________________________________

4. http://es.wikipedia.org/wiki/Capa_limite



21

FIG 6. BEHAI VOR OF THE FLOW WI TH A SPECIFIC GEOMETRY

http://2.bp.blogspot.com/_QcPSRUCyrgg/R9CMhTpGu2I/AAAAAAAAA6A/16ygrA-1mps/s400/p530.jpg



22

5. EGENEERING DEVELOPMENT

5.1 GENERATION OF THE AIRFOIL

After the engineer of design to delivered the information of the airfoil and the coordinates of

the airfoil under a degree zero, it prepares to create the new airfoil, this time with the angles

of entry of angered and with the information as the chord and the pertinent pitch.

FIG 7. THE FIRST AIRFOI L WI THOUT ANGLE OF INCIDENT

Having this already made airfoil one proceeds to define the airfoil according to the angle of

incident that is had, there does by means of the subtraction of alpha 2 between alpha 1 and

following this it does a series of operations multiplying this remaining angle by the cosines

and the sins of each one of the elements of the coordinates.

FIG 8. UP. AIRFOI L WITH ANGLE OF SANE INCIDENT AND PI TCH DOWN AIRFOI L WITH ANGLE OF INCIDENT

-0.1

0

0.1

0 0.2 0.4 0.6 0.8 1 1.2

AIRFOIL WITHOUT ANGLE

Series1

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018

DIFFERENCES BETWEEN THE AIRFOILS

Series1

Series2



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And finally the airfoil is created by the one that one is going to work to create the meshing.

FIG 9. AIRLFOI L WI TH ANGLE OF INCIDENCE, PITCH AND ADAPTED CHORD

When the airfoil is had already created one proceeds to realize another airfoil but in this one

already the pitch comes included, after it is created a cut is realized in the extrados and in

the intrados of both airfoils in such a way that the following figure is obtained

FIG 10 FINALLY AIRFOI L TO EXPORT TO GAMBIT

0.025

0.0255

0.026

0.0265

0.027

0.0275

0.028

0.0285

0.029

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018

FINALLY AIRFOIL

Series1

0.025524727

-0.04

-0.02

0

0.02

0.04

0.06

0.08

-0.04 -0.02 0 0.02 0.04 0.06

FINALLY AIRFOIL WITH BOUNDARY CONDITIONS

Series1

Series2



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5.2. GENERATION OF THE MESH

For the generation and the mesh it is necessary firstly that everything to establish a fewconditions of border for the airfoil this does that the mesh has a definite geometry and in the

moment to simulate in fluent the flown one to flow where we stipulate that it was flowing.

5.2.1. Already having the coordinates of the airfoil waterfall and the conditions of border

one proceeds to realize the mesh for the above mentioned object. The first thing that is done

is to define the initiate, the center and the exit of the system this procedure is realized in

gambit by means of lines and faces.

FIG 11. BOUNDARY CONDI TION FOR THE AIRFOIL



25

5.2.2. Followed to this there are defined the faces that they are going to work and one

proceeds to realize the set of meshes. In this step it is important to define the number of

nodes for the meshes since this defines since is going to be of the perfect above mentioned

mesh.

FIG 12. SET OF MESHES FOR THE AIRFOIL

5.2.3. Finally we save the airfoil already with the set of meshes in a format .msh in orderthat this way the program fluent could read it.



26

5.3. SIMULATION IN CFD-FLUENT

5.3.1.The first thing that we do in fluent is to import the set of meshes of the airfoil and toexecute a checkup to determine that erroneous fact had not stayed in gambit.

5.3.2. Followed to this we enter to the option solver which provides a series of options to us

for our case the option in that more we were interested it names green-gauss node-based

that on the basis of a mathematical model it determines and considers the nodose values to

calculate the gradient.



27

5.3.3. To continue with the simulation we determine the model of viscosity that we want to

use, in this case the model of viscosity uses k-epsilon. That specifies that in these conditions

there are used a turbulent flow and all the variables is calculated on the basis of this model.



28

5.3.4. The following step that is realized in the process of simulation is to check that the

scale that is used by us to realize the meshes in gambit be the same to realize the simulation

in fluent for this one proceeds to realize the correct adjustment of the scales.



29

5.3.5. Followed determining the scale of the simulation define the parameters of entry of the

system as it is the speed at the entry and the cosine and the sine of the angle of incident.

This allows us to direct the air flow that passes for the entry and throbs with the blades.



30

5.3.6. The following step that we must realize is of determining that in the moment of

iterates the result of these iterations of as a graph and not only as information.



31

5.3.7. Finally there is defined the number of iterations and the interval of reports. This is

realized for unstable calculations that there use mathematical specific and unstable models,

with this number the number of passages of time will be specified, since every iteration will

be a passage of time. And the interval of reports puts the number of the iterations that will

pass before the screen of convergence and these will be able to be seen in the shape of

information and graphs.

5.3.8. And already to finish the last thing that is realized are the respective graphs to:

- Static pressure

- Dynamic pressure

- Total pressure

- Velocity magnitude



32

- Velocity vectors

and the XY plot of:

- Velocity magnitude

- Total pressure.

5.4 RESULTS OBTAINED

FIG 13. STATIC PRESSURE



33

FIG 14. DYNAMIC PRESS URE



34

FIG 15. TOTAL PRESSURE



35

FIG 16. VELOCITY MAGNITUDE



36

FIG 17 VELOCITY VECTORS



37

FIG 18. XY PLOT VELOCITY MAGNITUDE



38

FIG 19. XY PLOT TOTAL PRESSURE



40

the simulation and continued to this the speed increases and diminishes gradually up to

finding a curve sinusoidal.



41

7. CONCLUSIONS

The first thing that I conclude after realizing the simulation is that the results of the

above mentioned simulation did not converge as it was planned since to many of the

variables that affect the work his obtained results were different from those who

thought to be obtained.

Another conclusion that it is possible to say on the simulation is that the points of

stagnation can avoid if the pitch number is corrected since this one influences

directly the geometry of the blade and of the whole system.

It is possible to come to improve the simulation if from the beginning the

mathematical model can change in order that the behavior of the air flow is differentin this case the model might have thought of Spalart-Allmaras.

In principle the fact of simulating in fluent is a great step for us due to the fact that

it had never been done of this form and neither for a airfoil of a compressor as

specifies case.



42

The most important conclusion is that in this work it was possible to compile all the

information and the equations and the mathematical models who met during the

semesters and classes of previous engines to put in practice and to solve cases of the

common one as it is an optimization of something that already this done.

This work not only serves with the specifications of engines if not with everything

what has reference with the aeronautical area and his applications to the industry,

this work also serves to demonstrate that an analysis of this type it is possible to do

with the tools that are had to the scope independently of the obtained results.



43

8. FUTURE WORK

For a future work it is possible to try to change the number of pitch and the speed of

entry to improve the properties of the system with this can eliminate the point of

stagnation.

For a future work we can improve the line of camber of the airfoil with this the

characteristics the airfoil would be better to the moment of qe the flow of the air

passes for the airfoil

For a future work it is possible to improve the conditions of the simulation if more

experience was had by the mathematical models who there appear this in order to

improve the results thrown for fluent.

And finally for a future work it is possible to choose several coordinates of airfoils to

be able to have one ideal of which it is the best airfoil and with this to be able to

choose the best for applied in the mission of the project and obtain better results

even more of the awaited ones



9. BIBLIOGRAPHY

BOOKS

- OÑATE. Antonio Esteban. Turborreactores, teoría, sistemas y propulsión deaviones. Madrid, 1981.Pag62.

- SARAVANAMUTTOO, Hih. Gas Turbine Theory. Edition 4.United Kingdom,1996.Pag 158-159.

- STECKIN, B.S. Teoría de los motores de reacción: Procesos y características.Madrid: Dossat, 1964

- NORMAS ICONTEC 1486, 2005

WEBS

- Http://www.faa.gov

- Http://www.uamerica.edu.co

- Http://www.fluidos.eia.edu.co

- Http://www.wikipedia.es

- Http://www.Fluent.Inc\fluent6.3.26\help\html\ug\node1354.htm

1rafael mauricio uribe niÑo 20061171036 group number 4

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