Sixth Pegasus-AIAA
Student Conference
Sevilla (Spain), April 29, 2010
Session:
Time:
A
9:00:00 AM
Paper:
1
Student Name:
Institution:
Country:
Paper Title:
Paper link:
Michael Konvalinka
CTU Prague
CZ
FEM Modal and Flutter Analysis of the G304S Glider
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Konvalinka_Prague.pdf
ABSTRACT
This paper provides information about FEM modeling of the G304S sport composite glider and its
subsequent modal and flutter analysis. In the first part, the design of the geometric and FEM model
including its control system is described. In the following part, natural frequencies and modal
shapes are numerically determined for several model configurations. The last section deals with the
calculation of aerodynamic damping coefficients and also evaluates the flutter resistance of the
structure based on the "Means of Compliance with FAR 23.629, Flutter" regulation.
1
Session:
Time:
A
9:30:00 AM
Student Name:
Institution:
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Paper Title:
Carmine Capone
Uni. Napoli
IT
Numerical Simulation of Fluid-Structure Interaction comparing SPH and ALE
Approaches
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Capone_Napoli.pdf
Paper link:
Paper:
2
ABSTRACT
Crash is an important research field not only regarding last time. One of the most important
research sector of transport industry is crashworthiness that in the last year is becoming always
more enclosure in design process of its product. Aerospace industry is very interested to find new
solutions and designs that could assure best behavior during crash phenomena. Clearly this field of
study can assure new important products, thought to be functionally and opportunely defined in
project contests. This is synonymous of configuration respect but also innovation of design systems
that act as crash innovations. In according to that, numerical and analytical studies are increasing
about the best methods to simulate impacts: the dual purpose of the research interests is to tune
innovative simulation techniques and optimizing airplane configuration in crashworthiness sphere.
The following work describes two new important numerical methods based on FE analysis,
performed to study impact phenomena: the investigation is focused on fluid-structure interaction
and it faces two different approach for the formulation of fluid field. ALE and SPH approaches are
used to simulate a water domain, in which a structural component impacts. To obtain the best
comparison with experimental tests and to underline the advantages and disadvantages of the
methods is the purpose of double formulation use.
2
Session:
Time:
A
10:00:00 AM
Student Name:
Institution:
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Paper Title:
Chiara Grappasonni
Uni. Roma
IT
Development of Operational Modal Analysis Methodologies for Dynamical
Identification of Vega Lunch-Vehicle Subsystems
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Grappasonni_Roma.pdf
Paper link:
Paper:
3
ABSTRACT
The main objective of this paper is the development of methodologies able to estimate the
dynamical behaviour of a structure undergoing its operative conditions. An overview of four
different approaches, representing the actual state of the art in the research field of the Operational
Modal Analysis, is provided along with the improvements suggested for damping ratios computing.
The Frequency Domain Decomposition and Hilbert Transform methods compared to the Stochastic
Subsystem Identification both in time and in frequency domain has been applied for modal
identification on some subsystems of Vega launch vehicle: the Solid Rocket Motor of the first stage,
P80, during the qualification firing test and the tank of the upper module, AVUM, during the
vibration bench tests.
3
Session:
Time:
A
10:30:00 AM
Student Name:
Institution:
Country:
Paper Title:
Benjamin Greiner
Uni. Stuttgart
DE
Operational Modal Analysis and its Application for SOFIA Telescope Assembly
Vibration Measurements
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Greiner_Stuttgart.pdf
Paper link:
Paper:
4
ABSTRACT
This paper deals with the application of Operational Modal Analysis for vibration measurements of
the Telescope Assembly of the Stratospheric Observatory For Infrared Astronomy (SOFIA).
Operational Modal Analysis acquires information about the dynamic characteristics of a structure in
terms of eigenfrequencies, damping and mode shapes, without the need for explicit measurement of
the vibration inducing loads. Since the exact influence of aerodynamic disturbance loads during
operational flight conditions is not measurable, the Operational Modal Analysis approach is a
promising contribution the SOFIA optimization effort. Although no measurements could be
conducted during actual flight conditions within the scope of the study, the study shows that the
approach of Operational Modal Analysis is feasible for the optimization process of the telescope.
Two major techniques used in Operational Modal Analysis – Frequency Domain Decomposition
and Stochastic Subspace Identification – are discussed with respect to their mathematical concept.
The paper also presents the work done in preparation of future measurements by the definition of
instrument configuration files and the design of a data format conversion tool.
4
Session:
Time:
A
11:30:00 AM
Paper:
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Paper Title:
Paper link:
Petr Novacek
CTU Prague
CZ
The Attitude Estimation using IMU/GPS and Adaptive Filtering
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Novacek_Prague.pdf
5
ABSTRACT
This paper deals with the GPS usage for the attitude determination and IMU/GPS integration. GPS
system is widely used as the source of position, velocity, and time information; however there is
also other possibility of its usage which is the attitude determination capability. Several possible
methods to determine GPS based attitude are presented after an introduction. The last presented
method is closely described with appropriate hardware equipment. The GPS based attitude
measurement results are presented later on. The last part describes the integration of IMU and GPS
as a potential future development.
5
Session:
Time:
A
12:00:00 PM
Paper:
Student Name:
Institution:
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Paper Title:
Paper link:
Javier Mateo Bonilla, José Rodríguez Morales
ESI Sevilla
ES
Light System’s Controller
http://www.pegasuseurope.org/AIAA_Pegasus/Papers/MateoRodriguez_Sevilla.pdf
6
ABSTRACT
Nowadays, every aeroplane’s light is controlled by means of individual switches. Since planes need
to use multiple lights, it requires setting a high number of switches in the cockpit, and a remarkable
level of attention from the pilot. The system we propose simplifies this action. The pilot will just
need to push a single button to change from one light configuration to another automatically.
6
Session:
Time:
A
12:30:00 PM
Paper:
7
Student Name:
Institution:
Country:
Paper Title:
Paper link:
Juan Baena Castillo, María del Carmen Anton
ESI Sevilla
ES
Lab view Simulation of ILS (Instrumental Landing System)
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/BaenaAnton_Sevilla.pdf
ABSTRACT
This paper presents an ILS-DME simulation development with a graphical programming for
measurement and automation, called Labview. ILS-DME is a ground-based instrument approach
system that provides precision guidance to an aircraft approaching and landing on a runway. This
simulation shows the principal displays for the approach to the runway, and it intends to show the
information that a pilot receives on his screen. With this information an aircraft will be able to land
at the airport in spite of bad meteorological conditions. This simulation is based at the Seville´s
airport, using real dates; but it will be able to be used at any other airport.
7
Session:
Time:
A
2:45:00 PM
Paper:
Student Name:
Institution:
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Paper Title:
Paper link:
Yago Urroz
UPM Madrid
ES
Hydrodynamic and Thermal Study of Biofilms for Aerospace Applications
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Urroz_Madrid.pdf
8
ABSTRACT
Application of bacterial biofilms as a thermal microbiosensor is an innovative procedure. Adhesion
to brass surfaces with different roughness (0.5, 1, 2.5 and 3.75 μm) of Pseudomona putida biofilms
was studied in situ, under variable flow conditions (Reynolds number was equal to 0, 60, 500 and
1000). In order to optimize the geometry of the experimental device, we have used a CFD software
(SolidWorks combined with TermoFlo) that helped us to obtain a fully developed flow inside the
channels. Besides, we tested a Proportional (P) Thermal Control System (TCS) and a Proportional
Integral Differential one (PID) to guarantee a range of temperatures in the experimental equipment
that assured the survival of the bacteria. The overall results emphasize the difficulty to obtain a
uniform layer biofilm of Pseudomona putida on brass and its weakness when exposed to a water
flow. An improvement in the growth technique of the biofilm on brass is thus necessary, e. g.,
providing nutrients during the whole growing process.
8
Session:
Time:
A
3:15:00 PM
Student Name:
Institution:
Country:
Paper Title:
Gianfranco Laguardia
Politecnico Torino
IT
ANALYSIS OF WSB TRANSFERS FOR AN EARTH-MOON SYSTEM FOR
THE EUROPEAN STUDENT MOON ORBITER (ESMO) PROJECT
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Laguardia_Torino.pdf
Paper link:
Paper:
9
ABSTRACT
This paper presents the study performed at mission analysis level for the European Student Moon
Orbiter (ESMO). The baseline transfer, selected for the flight to the Moon, exploits the Weak
Stability Boundary (WSB) region of the Earth-Sun-Moon system. This study presents the trajectory
design and the navigation analysis for the transfer of the target Moon orbit, explaining the reasons
why this low-thrust transfer should be preferred compared to the other classical space transfers. The
launch window analysis represents a key point of this study since the spacecraft will be launched as
secondary payload and thus, the orientation of the initial GTO (Geostationary Transfer Orbit) will
depend on the primary spacecraft. Furthermore, the survivability of the spacecraft at the Moon
depends on the arrival geometry.
9
Session:
Time:
A
3:45:00 PM
Paper:
Student Name:
Institution:
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Paper Title:
Paper link:
Marco Giannini
Politecnico Torino
IT
Multi-Tethered Satellite Formations Dynamics
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Giannini_Torino.pdf
10
ABSTRACT
The dynamics of a rotating open multi-tethered satellite formation is here investigated, considering
a model that includes the inertial properties of the cables in order to evaluate the dynamic evolution
of the system under the action of gravity gradient force and tether tension. The results obtained for a
simple, massless tether model are compared with those derived for a model where the tethers are
modeled by means of a sequence of point-masses connected by massless springs and dampers
("bead model"). The analyses, performed by means of numerical simulation of the considered
models, shows that the introduction of the tether lateral dynamics produces some little discrepancies
wrt the massless model, especially in terms of elongations, that reflects on the deputies positions
and could be of disturb for sub-millimetrical interferometric missions. Once the dynamic behavior
of the formation is identi ed for the nominal values of
tether characteristics, a parametric analysis with respect to tether linear mass, damping and stiffness
is also discussed starting assuming a linear variation of their values with tether cross
section.
10
Session:
Time:
A
4:45:00 PM
Paper:
Student Name:
Institution:
Country:
Paper Title:
Paper link:
Stefania Oliva
Politecnico Torino
IT
Analysis of manned Earth-Moon missions
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Oliva_Torino.pdf
11
ABSTRACT
In this work we develop a tool for the fast evaluation of how variations of the design parameters
change the masses of each phase and each module for an Earth-Moon manned mission. Starting
from the study of NASA’s Constellation Program, we analyze the influence of the modifications of
the height of the low lunar orbit, the choice of the propellant for each engine and the distribution of
the ΔV, highlighting that only the last one is feasible and may produce advantages on the initial
mass of the mission.
11
Session:
Time:
A
5:15:00 PM
Paper:
Student Name:
Institution:
Country:
Paper Title:
Paper link:
Frédéric Cristini
ISAE Toulouse
FR
Satellite networks: a solution against emerging space threats
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Cristini_Toulouse.pdf
12
ABSTRACT
In addition to natural space environment hazards, space systems may be subject to emerging threats
coming from the artificial space environment. The objective of our work is to design satellite
systems being intrinsically threat-tolerant. Two different system architectures based on specialized
networked small satellites are proposed: a "swarm constellation" architecture and a "networked
constellation" architecture. Both are assessed through several operational criteria.
12
Session:
Time:
A
5:45:00 PM
Paper:
13
Student Name:
Institution:
Country:
Paper Title:
Paper link:
Roderik Koenders
TU Delft
NL
Where to land on Mars: selecting the best landing site for the ExoMars mission
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Koenders_Delft.pdf
ABSTRACT
Only two nations have successfully achieved soft landings on the Moon or Mars: Russia and the
United States of America. Europe wants to join this community in this decade by sending its own
probe to the surface of Mars: ExoMars. An essential issue for the success of the mission is where to
land. Landing-site selection is a process in which a diverse group of experts, which are often
geographically distributed, need to find a location that minimizes the risk of failure during landing,
and maximizes the chance of fulfilling the scientific and exploration goals of the mission. In this
paper we identify the challenges facing Europe to select a safe, and scientifically interesting landing
site for ExoMars, and propose several methods that will facilitate the process of landing-site
selection for future missions.
13
Session:
Time:
G
9:00:00 AM
Student Name:
Institution:
Country:
Paper Title:
Pierluigi Della Vecchia
Uni. Napoli
IT
AERODYNAMIC ANALYSIS AND OPTIMIZATION OF A REGIONAL
TRANSPORT AIRCRAFT
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/DellaVecchia_Napoli.pdf
Paper link:
Paper:
1
ABSTRACT
The geometry of a typical regional transport aircraft is modified to reduce drag and improve
performances, in particular cruise speed. Once performed a preliminary aerodynamic analysis on
the original geometry, in order to detect those portions of the body shape whose modification
mostly influences drag variation, an automatic procedure, manageable trough MATLAB, allows to
modify those parts using interpolating curves and surfaces, respectively NURBS and
NURBCOONS. Within the modification loop, each new geometry is analyzed trough a panel code
solver until optimized shapes are found. Finally, the optimized body is exported into a CAD format
(IGES) suitable for design and production. The optimization process has guaranteed a reduction of
3 percent of the total drag and an increase of 2 percent of cruise speed respect to the original
configuration.
14
Session:
Time:
G
9:30:00 AM
Student Name:
Institution:
Country:
Paper Title:
Joost Venrooij
TU Delft
NL
Understanding the role of the neuromuscular dynamics in biodynamic feedthrough
problems
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Venrooij_Delft.pdf
Paper link:
Paper:
2
ABSTRACT
Biodynamic feedthrough (BDFT) refers to a phenomenon where accelerations cause involuntary
limb motions which, when coupled to a control device, can result in unintentional control inputs.
This study aims to increase the understanding of BDFT, and the role of the neuromuscular system
(NMS) in particular. The fundamental question driving this research is how accelerations are
transferred through the human body, i.e., through the NMS, and how the exact setting of the NMS
influences this feedthrough. As the neuromuscular system differs from person to person and is
highly adaptable, it is expected that BDFT does not only vary from person to person, but that also a
single person can express a range of BDFT dynamics by adaptation of the neuromuscular settings.
To investigate this hypothesis, use is made of the neuromuscular admittance, which describes the
dynamic response of human limbs in response to force disturbances. A measurement method was
developed to measure neuromuscular admittance and BDFT simultaneously. The results from this
experiment confirm that the neuromuscular system plays such a large role in the occurrence of
BDFT that the variability of the neuromuscular system cannot be ignored when investigating BDFT
problems. Based on the experimental data a BDFT model was developed. The model parameters
were estimated by fitting the model on the experimental data. The model successfully captures
BDFT dynamics in both the frequency domain and the time domain, for different subjects and
different settings of the neuromuscular system.
15
Session:
Time:
G
10:00:00 AM
Paper:
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Paper Title:
Paper link:
Michael Mößner
TU Braunschweig
DE
Training Algorithms based on Stabiiity Theories for Neural Flight Controllers
http://www.pegasuseurope.org/AIAA_Pegasus/Papers/Moessner_Braunschweig.pdf
3
ABSTRACT
The idea of using neural network controllers in unmanned airplanes led to the demand of stable
training algorithms. In this article the stability of the standard Gradient Descent training method is
examined. Thereafter the Gradient Descent method is combined with the principle of Sliding Mode
control which promises robustness and stability. The algorithms are implemented in a simulation
environment with a neural network controlling structure which consists of a neural controller and a
neural observer. The neural networks were trained online during a flight simulation. For the
observer training the Sliding Mode Control algorithm obtained very good results.
16
Session:
Time:
G
10:30:00 AM
Paper:
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Institution:
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Paper Title:
Paper link:
Alessandro Scola
AIAA section
IT
Design of a quad-rotor mini Unmanned Air Vehicle (UAV)
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Scola_AIAA.pdf
4
ABSTRACT
Nowadays the development of small and mini Unmanned Air Vehicles (UAV) is an important topic
both for military and civilian applications. A four rotary-wing UAV, named quad-rotor, has been
studied and designed. In the design process the size of the quad-rotor and the geometrical properties
of the structure were decided to withstand the imposed loads. After that, the on-board equipments as
batteries, engines, propellers, engine speed controllers and the flight controller board were selected.
Subsequently, the mathematical model, describing the flight dynamics of mini quad-rotor, was
developed. In conclusion, as work verification, the hover manoeuvre was simulated.
17
Session:
Time:
G
11:30:00 AM
Student Name:
Institution:
Country:
Paper Title:
Juan Tendero
UPM Madrid
ES
Optimization of Flight Profile to Minimize Fouling in Helicopter Gas Turbine
Engines
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Tendero_Madrid.pdf
Paper link:
Paper:
5
ABSTRACT
The present research is the first attempt to optimize helicopter flight profiles taking compressor
fouling into account. The main effects of particle ingestion in a gas turbine engine are a substantial
reduction of the engine life and a significant deterioration of engine performance. In order to
achieve the objectives, it is necessary to understand both the degradation mechanisms and the way
to reduce them. This paper concludes that there is an altitude between 1,000 and 1,500 m, which
minimizes degradation with the lowest impact on the flight time. In this region, particles can not be
completely eliminated, thus filters and washing must be still used. This is the first step in the
assessment of this aim and some areas need further work to be fully understood.
18
Session:
Time:
G
12:00:00 PM
Paper:
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Institution:
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Paper Title:
Paper link:
Alessandro Turchi
Uni. Roma
IT
Numerical Study of Throat Erosion in Solid Rocket Motor Nozzles
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Turchi_Roma.pdf
6
ABSTRACT
In the present work, a validated integrated theoretical/numerical framework has been used to study
the erosion of graphite nozzle material in solid rocket motor environments. With this approach, the
numerical study of nozzle erosion has been carried out considering the role of propellant
composition and nozzle geometry at first. Then the geometrical effect has been investigated
(performing several calculations) varying the nozzle scale and entrance length. These simulations
show that nozzle throat erosion rate reduces as a consequence of boundary layer thickening when
the nozzle entrance length increases. Finally an analysis to investigate the erosion rate dependence
on chamber pressure has been carried out. Results show that erosion rate increases with a nearly
linear dependence with chamber pressure, whereas it is only marginally affected by chamber
composition (which changes because of different chamber conditions).
19
Session:
Time:
G
12:30:00 PM
Paper:
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Paper Title:
Paper link:
Sebastiano Giannelli
Uni. Pisa
IT
MPD Thruster Onset and Current Filamentation
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Giannelli_Pisa.pdf
7
ABSTRACT
Future manned space exploration missions require the availability of high-power, reliable and
efficient propulsion systems. Electric thrusters seem to be the only cost-effective mid-term available
option and among them magnetoplasmadynamic (MPD) thrusters offer the better combination of
thrust-density and specific impulse levels for crewed mid and long-range missions. They are
affected, however, by low thrust efficiency values and, when critical conditions are reached in terms
of operating parameters, they enter an unstable regime known as onset. We propose an explanation
of the onset phenomenon based on a stability analysis of a two-fluid model for the azimuthal
dynamics of the plasma in the MPD channel, revealing the possibility that a current filamentation
instability (CFI) occurs near critical conditions, leading to azimuthal symmetry breaking and
terminal voltage fluctuations.
20
Session:
Time:
G
2:45:00 PM
Paper:
Student Name:
Institution:
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Paper Title:
Paper link:
Pedro Paredes
UPM Madrid
ES
Analysis of Subgrid Scale closures for The Vorticity Transport Equations
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Paredes_Madrid.pdf
8
ABSTRACT
The present work involves a comprehensive study of the applicability and accuracy of subgrid scale
closures for Large Eddy Simulations (LES) using the Vorticity Transport Equations (VTE).
Specifically, the Smagorinsky, Dynamic Smagorinsky and Dynamic Mixed models are formulated
and applied to the VTE and are solved using a pseudospectral approach. A forced, homogeneous,
isotropic turbulence flowfield obtained from Direct Numerical Simulations is used to perform a
priori investigations of the accuracy and consistency of the new formulations. Following this, the
models are applied in an LES framework to simulate high Reynolds number isotropic turbulence
and to the Taylor Green Vortex (TGV) problem.
On applying the filtering operation to the VTE, unclosed Sub-Filter Scale (SFS) terms appear as a
result of the non-linearity of the original equations. The dynamic models, in which the
multiplicative coefficient in the model of SFS terms are determined as part of the solution, were
seen to perform much better than the basic Smagorinsky model across all test cases, primarily as
they are less diffusive. The SFS terms can divided in to two parts: one that reflects vortex transport
by SFS velocity fluctuations and the second one represents SFS vortex stretching and tilting due to
the unresolved motion. The Dynamic Smagorinsky model is seen to correlate well only with the
convective portion of the SFS torque whereas the Dynamic Mixed model shows a strong correlation
with both parts, thus presenting the viability of the VTE-LES method as a promising and perhaps a
better alternative to conventional velocity-pressure based LES formulations.
21
Session:
Time:
G
3:15:00 PM
Paper:
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Paper Title:
Paper link:
Stefano Discetti
Uni. Napoli
IT
On a Rapid Algorithm for PIV Image Processing
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Discetti_Napoli.pdf
9
ABSTRACT
A multi-grid method to reduce the processing time in Particle Image Velocimetry (PIV) is presented.
The technique relies on the subsampling of the images in the initial steps of the process, in order to
calculate a predictor velocity field with less computational effort. The process implies a remarkable
reduction of computational cost in calculating the cross-correlation map, at the expense of the
execution of supplementary operations for the construction of the subsampled images. Performance
assessment is conducted by using synthetic images with particles of Gaussian shape; the results
with sinusoidal displacement field, in a wide range of seeding density, are presented. An
experimental application of the novel multi-grid method is also illustrated. The results show that the
processing of the images can be executed even 4 times faster, allowing the possibility of obtaining
very accurate results in real time during the execution of the experiment.
22
Session:
Time:
G
3:45:00 PM
Paper:
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Paper Title:
Paper link:
Giuseppe Trapani
Cranfield
UK
Computational Aerodynamic Design for 2D High-Lift Airfoil Configurations
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Trapani_Cranfield.pdf
10
ABSTRACT
Multi-objective and multi-disciplinary design optimization tools are becoming a necessity for the
development of innovative and more efficient advanced aerodynamic configurations. The highly
complex flow-field that develops around such airfoils and the computational cost to accurately
simulate and extract the crucial flow metrics represent a challenging task for the design
optimization process. This paper describes the development of an integrated automated multiobjective optimization system for the design of high-lift airfoil configurations. The developed
system integrates an existing parameterization routine, adapted to the requirements of the specific
application, the Multi-Objective Tabu Search (MOTS) optimization toolkit and commercial
Computational Fluid Dynamics (CFD) packages for the automatic mesh generation (Pointwise) and
flow evaluation (CFX). An initial optimization study of a 2D three-element real-world test case
airfoil has been executed. The preliminary results reveal the full functionality and integrity of the
computational design tool and the ability to improve the performance of such complex
aerodynamic con gurations. Three different optimum solutions from the pareto optimal set are
analyzed and compared against the datum design in detail. The performance of MOTS as an
optimization strategy for this type of aerodynamic design applications is also analyzed and assigned.
23
Session:
Time:
G
4:45:00 PM
Student Name:
Institution:
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Paper Title:
Matthias Lengers
TU Braunschweig
DE
Stereo PIV measurements of transitional boundary layers of a three-dimensional
pitching and plunging Airfoil
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Lengers_Braunschweig.pdf
Paper link:
Paper:
11
ABSTRACT
This student research project deals with the investigations of the flow phenomena over a three
dimensional moving airfoil. The complex motion apparatus was set up to create a pitching, plunging
and rolling movement of a two dimensional wind tunnel model. The main objective was to
determine the position of transition with respect to the phase angle and span-wise distribution. The
campaign focussed Stereo PIV measurements, but also Mini Tuft-, Oilfilm- and SSLCCTechniques, contributed to the results. It can be shown that the flow field is not dominated by sidewall effects, while the transition oscillates corresponding to the spanwise variation of the heaving
cycle.
24
Session:
Time:
G
5:15:00 PM
Student Name:
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Paper Title:
Daniel Klatt
Uni. Stuttgart
DE
Development and Applications of the CBOS Technique for the Determination of
Light Deflections Caused by Density Gradients in Compressible Flows
http://www.pegasus-europe.org/AIAA_Pegasus/Papers/Klatt_Stuttgart.pdf
Paper link:
Paper:
12
ABSTRACT
The improved Background Oriented Schlieren technique CBOS (Colored Background Oriented
Schlieren) is described and applied to determine the flow field around different test models. The
technique allows to measure the light deflection caused by density gradients in a compressible flow.
For this purpose the distortion of the image of a background pattern observed through the flow is
used. In order to increase the performance of the conventional Background Oriented Schlieren
(BOS) technique, the monochromatic background is replaced by a colored dot pattern. The different
colors are treated separately using suitable correlation algorithms. Therefore, the precision and the
spatial resolution can be highly increased. The CBOS technique is explained and applied in order to
measure the flow field around a free-flight space model and an asymmetric mounted spike-bodyconfiguration in a supersonic wind tunnel. Furthermore a reconstruction of the density distributions
of the three-dimensional flow fields by applying a tomographic reconstruction method to the CBOS
measurements is shown. The reconstructed density fields are compared with the results from
numerical simulations of the flow field.
25