timo ojanen aero-vibro acoustic simulation of an ultrahigh

86 Pages·2016·2.58 MB·English

by  Timo Ojanen

TIMO OJANEN
AERO-VIBRO ACOUSTIC SIMULATION OF AN ULTRAHIGH-
SPEED ELEVATOR

Master of Science thesis

Examiner: prof. Reijo Karvinen
Adviser: D. Sc. Gabriela Roivainen,
KONE Corporation
Examiner and topic approved by the
Faculty Council of the Faculty of
Engineering Sciences on 12th Au-
gust 2015
i

ABSTRACT
Timo Ojanen: AERO-VIBRO ACOUSTIC SIMULATION OF AN ULTRAHIGH-
SPEED ELEVATOR
Tampere University of Technology
Master of Science Thesis, 71 pages, 7 Appendix pages
February 2016
Master’s Degree Programme in Mechanical Engineering
Major: Energy and Process Technology
Examiner: Professor Reijo Karvinen

Keywords: Acoustics, Elevator, CFD, FEM, BEM, SEA, Simulation

There are many solutions for computing sound and each one of them have advantages
and limitations. The challenge when using deterministic methods for acoustic simula-
tion in case of complex application, derives from the need of accurate vibrational re-
sponse of the model. Validating each mode of a complex structure, when the frequency
range of interest covers hundreds of natural frequencies is expensive. In addition, in
order to have accurate response, the model cannot be oversimplified and due to its size,
the computation is long. The advantage of using statistical methods derives from lower
requirements for validating each eigenfrequency, because average energies are consid-
ered. In addition the dimensional and material tolerances have lower impact on final
results. However the method is less accurate for a specific solution with a clear tonal
resonance.
In this study a hybrid method has been chosen: for lower frequencies where the tonal
resonances are significant a finite element method was applied; for higher frequencies a
statistic energy method has been chosen. The combination between the two methods has
been performed in the multiphysics environment software VA One.
There are several sources of sound inside an elevator shaft, which have to be evaluated
in order to assess their impact on the sound inside the car. For this reason test data have
been used for determining some of the vibrational contribution, computational fluid
dynamics for computing the “wind” contribution and boundary element method for
computing the acoustic reverberant contribution of the shaft.
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TIIVISTELMÄ
TIMO OJANEN: SUURNOPEUSHISSIN AERO-VIBROAKUSTINEN
SIMULOINTI
Tampereen teknillinen yliopisto
Diplomityö, 71 sivua, 7 liitesivua
Helmikuu 2016
Konetekniikan diplomi-insinöörin tutkinto-ohjelma
Pääaine: Energia- ja prosessitekniikka
Tarkastaja: professori Reijo Karvinen

Avainsanat: Hissi, CFD, SEA, FEM, BEM, Akustiikka, Simulointi
Äänen simuloimiseen on monia menetelmiä, mutta jokaisella niistä on etunsa ja
rajoituksensa. Determinististen menetelmien haaste monimutkaisten systeemien
akustiikkasimuloinnissa johtuu tarkan värähtelyvasteen tarpeesta, jonka määrittäminen
sadoille ominaistaajuuksille on kallista. Lisäksi tarkan vasteen määrittämiseksi malli ei
saisi olla liian yksinkertaistettu, jolloin sen koko kasvaa, jonka myötä myös laskenta-
ajat kasvavat. Tilastollisia menetelmiä käytettäessä tarve määrittää jokainen erillinen
ominaistaajuus vähenee sillä näiden sijaan systeemien keskimääräiset energiat
määritellään. Lisäksi geometrisilla yksityiskohdilla ja materiaaliominaisuuksien tarkalla
määrittämisellä on pienempi vaikutus lopullisiin tuloksiin.
Tässä työssä menetelmäksi on valittu hybridimenetelmä, jossa alemmilla taajuuksilla,
joilla yksittäiset resonanssitaajuudet ovat merkittäviä, ratkaisu saadaan elementti-
menetelmällä. Puolestaan korkeammat taajuudet ratkaistaan käyttäen tilastollista
energia-analyysiä. Nämä kaksi menetelmää on yhdistetty simulointiohjelmisto VA
One:ssa, jota käytetään työssä äänenpaineiden simuloimiseen.
Hissikuilussa on useita äänilähteitä, jotka täytyy määritellä, jotta niiden vaikutus korin
äänenpainetasoon pystytään ratkaisemaan. Tämän takia testidataa on käytetty
määrittelemään rakenteiden kautta syntyviä äänilähteitä, virtauksesta aiheutuvat
äänilähteet on määritetty virtaussimuloinnilla, johon on ratkaistu akustiset ominaisuudet
ja heijastukset hissikuilusta reunaelementtimenetelmän avulla.
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PREFACE
This thesis brings my time as a student, which sometimes has felt endless, to its end.
First of all I want to thank Gabriela Roivainen for providing this topic for my thesis and
for guidance and help throughout the work.
I would also like to thank Aki Karvonen for the trust and the chance to make my thesis
at KONE and Giovanni Hawkins and Mikko Vesterinen for their help and patient atti-
tude towards my questions.
The simulation process would not have been possible without Antti Lehtinen who guid-
ed me with CFD simulations and numerous other topics and Jukka Tanttari who has
helped me with statistical energy analysis and acoustics.
I also thank my professor Reijo Karvinen for his role as the examiner and for many
good and inspiring courses in fluid dynamics.
I thank also my family. You have always supported me and sometimes in overly manor.
I would also like to thank my friends for bringing a lot of color and disturbance, some-
times too much, in my life to make the journey meaningful. Most of all I am in great
debt of gratitude to my girlfriend Elina who has tolerated me and made sacrifices to
stand by me.

Hyvinkää, 22.3.2016
Timo Ojanen
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CONTENTS
1. INTRODUCTION .................................................................................................... 1
2. ELEVATOR .............................................................................................................. 3
2.1 Double Deck Elevator .................................................................................... 6
2.2 Sound in Elevator ........................................................................................... 7
2.3 Acoustic and convective component ............................................................ 10
2.3.1 Structure Borne Transfer Path........................................................ 12
2.3.2 Airborne Transfer Path................................................................... 13
3. BACKGROUND .................................................................................................... 14
3.1 Previous Work .............................................................................................. 14
3.2 Literature Review ......................................................................................... 14
3.2.1 Elevator .......................................................................................... 15
3.2.2 Automotive..................................................................................... 16
3.2.3 Train ............................................................................................... 17
4. THEORY ................................................................................................................ 19
4.1 Theory of Vibro-acoustic Simulation Model ............................................... 19
4.1.1 Statistical Energy Analysis ............................................................ 19
4.1.2 Finite Element Method................................................................... 21
4.1.3 Hybrid method: SEA and FEM ...................................................... 22
4.2 Computational Fluid Dynamics ................................................................... 24
4.2.1 Reynolds Averaged Navier Stokes equations ................................ 25
4.2.2 Large Eddy Simulation .................................................................. 26
4.2.3 Detached Eddy Simulation............................................................. 26
4.2.4 Convective Component .................................................................. 27
4.3 Boundary Element Method .......................................................................... 28
4.3.1 Acoustic Component ...................................................................... 29
5. SIMULATION ........................................................................................................ 30
5.1 CFD .............................................................................................................. 31
5.1.1 Mesh ............................................................................................... 33
5.1.2 Modeling of turbulence .................................................................. 33
5.1.3 Q-criterion ...................................................................................... 35
5.2 Corcos Parameters ........................................................................................ 35
5.3 Boundary Element Method .......................................................................... 39
5.4 Structural Loads ........................................................................................... 42
5.5 Hybrid SEA-FEM ........................................................................................ 44
5.5.1 Simulation Models ......................................................................... 44
6. RESULTS AND DISCUSSION ............................................................................. 47
6.1 CFD Results and comparison ....................................................................... 47
6.2 Convective Component: Source Pressures ................................................... 53
6.3 Acoustic Component .................................................................................... 55
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6.4 Structural Contribution to SPL ..................................................................... 58
6.5 Total Sound Pressure Levels ........................................................................ 59
6.6 Component Development Proposals ............................................................ 64
6.7 Future Work ................................................................................................. 64
7. CONCLUSIONS ..................................................................................................... 66
REFERENCES ................................................................................................................ 67
APPENDIX 1: DERIVATION OF N-S EQUATIONS .................................................. 72
APPENDIX 2. DEFINING ACOUSTIC COMPONENT FROM COMPRESSIBLE
CFD DATA ..................................................................................................................... 76
APPENDIX 3. THE CFD DRIVING FILE .................................................................... 78
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LIST OF SYMBOLS AND ABBREVIATIONS
BEM Boundary Element Method
CAA Computational Aeroacoustics
CFD Computational Fluid Dynamics
DAF Diffusive Acoustic Field
DD Double Deck Elevator
DES Detached Eddy Simulation
FEA Finite Element Analysis
FEM Finite Element Method
FFT Fast Fourier Transform
LC Lower Car
LES Large Eddy Simulation
PSD Power Spectral Density, Auto Spectrum
PWF Propagating Wave Field
RANS Reynolds-averaged Navier-Stokes equations
S-A Spalart-Allmaras turbulence model
SEA Statistical Energy Analysis
SPL Sound Pressure Level
SRS Scale-resolving Simulation
SGS Sub-Grid Scale model of LES
TBL Turbulent Boundary Layer
UC Upper Car
VIBES Vibration Excellences

a Acceleration [m/s2]
α Decay Coefficient in x-direction
x
α Decay Coefficient in y-direction
y
Loss Matrix
C Courant number
c Speed of sound
D Dynamic stiffness matrix
Kronecker delta

E Energy [J]
η Loss factor
F Force [N]
f Frequency [Hz]
G Green’s function
g Gravity [m/s2]
i Imaginary number
k Acoustic wavenumber [1/m]
k Convective wavenumber [1/m]
c
k Turbulence kinetic energy [J]
t
L Sound pressure level [dB]
p
m Mass [kg]
Ma Mach number
N Mode count
n Modal density
Ω Vorticity tensor
ij
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ω Angular frequency [rad/s]
μ Turbulent viscosity
t
∇ Vector operator
P Power [W]
p Pressure [Pa]
q Degree of freedom
R Correlation function
ρ Density [kg/m3]
S Strain tensor
ij
S Cross spectrum
pp
t Time [s]
∆t Time step [s]
Lighthill’s stress tensor [N/m2]

τ Stress tensor in [N/m2]
ij
U Free stream velocity
u Velocity vector
v Vibration velocity [m/s]
∆x Mesh size [m]
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1. INTRODUCTION
As the buildings are getting higher and hence the time of the travel in elevator is longer
the increased speed of the elevator is one solution to reduce the travelling time. And as
the speed increases the sound pressure levels inside the elevator rises. In this thesis the
effect of the increased speed to the sound pressure level is studied.
At first the elevator basics are introduced. A description of technology in traction
sheave elevator is given and also as in this thesis the simulations are run by using a
model of a Double Deck elevator, a brief introduction is presented. The basics of sound
in elevator are also discussed.
The background of this thesis is presented in Chapter 3. A description of previous work
is given and a brief discussion about Vibration Excellences –project in which the sound
pressure level simulation inside the elevator car was started. The previous work by
Schreiber (2015) has been concentrating more on the structure borne noise as in this
work the main focus in the noise induced by the aeroacoustic excitations. Also a litera-
ture review of alternative techniques of noise simulation in elevators, cars and trains is
presented.
The theory of the simulation is given in Chapter 4. The theory of computational fluid
dynamics is introduced and also the turbulence modeling technique used in this work.
The theory of solving aeroacoustic loads from flow simulation by using boundary ele-
ment method (BEM) and coupling them to the vibro-acoustic solver is presented and the
principles and basic equations of statistical energy analysis are shown.
In Chapter 5 the simulation process of the work is described. Major part of the simula-
tion consisted of the defining of the aeroacoustic loads and the process to obtain them
and then processing the data to suitable form to utilize them in the vibro-acoustic simu-
lation. The flow simulation was done in co-operation with Antti Lehtinen of FS Dynam-
ics. The acoustic BEM simulations were done by Jukka Tanttari at VTT. Finally the
simulated source data was imported to the vibro-acoustic simulation software VA One
to simulate the sound pressure levels in the elevator.
The results from the simulations are discussed in Chapter 6. A comparison between two
simulations with the speeds of 10 and 15 m/s is given. The results from the flow simula-
tion and acoustic source components are compared and also the simulated sound pres-
sure levels in elevator cars. Also the structural contribution from the roller guides and
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ropes to the sound pressure level is presented. Finally the potential developments, future
work and possibilities of the simulation model and obtained data are suggested.