Experimental aerodynamics

485 Pages·2017·57.36 MB·English

by  Discetti

Experimental Aerodynamics

Experimental Aerodynamics
Edited by
Stefano Discetti and Andrea Ianiro
Cover image credit: Andrea Sciacchitano, Giuseppe Carlo Alp Caridi, and Rakesh Yuvaraj
CRC Press
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Library of Congress Cataloging-in-Publication Data
Names: Discetti, Stefano, editor. | Ianiro, Andrea, editor.
Title: Experimental aerodynamics / [edited by] Stefano Discetti and
Andrea Ianiro.
Description: Boca Raton : CRC Press, 2017.
Identifiers: LCCN 2016040406 | ISBN 9781498704014 (hardback : alk. paper)
Subjects: LCSH: Aerodynamics–Mathematical models. | Aerodynamics–
Experiments. | Experimental design.
Classification: LCC TA358 .E97 2017 | DDC 629.132/300724--dc23
LC record available at https://lccn.loc.gov/2016040406
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Contents
Preface vii
Editors ix
Contributors xi
i
Section
Fundamentals aspects of experimental aerodynamics
1 theoretical fundamentals of experimental aerodynamics 3
ANDREA IANIRO AND STEFANO DISCETTI
2 Statistical data characterization and elements of data processing 25
STEFANO DISCETTI AND ANDREA IANIRO
3 experimental facilities: Wind tunnels 55
ANDREA SCIACCHITANO
4 Principles of flow visualization 91
JAVIER RODRÍGUEZ-RODRÍGUEZ
ii
Section
Scalar measurements
5 Pressure measurements 109
DANIELE RAGNI
v
vi CONTENTS
6 temperature and heat flux measurements 143
FRANCESCO PANERAI
7 Density-based methods 195
FYODOR GLAZYRIN
8 From interferometry to color holography 223
JEAN-MICHEL DESSE
iii
Section
Velocity measurements
9 thermal anemometry 257
RAMIS ÖRLÜ AND RICARDO VINUESA
10 Laser velocimetry 305
JOHN J. CHARONKO
11 Volumetric velocimetry 357
FILIPPO COLETTI
iV
Section
Wall shear and force measurement
12 Measurement of wall shear stress 393
RICARDO VINUESA AND RAMIS ÖRLÜ
13 Force and moments measurements 429
MARIOS KOTSONIS
Index 449
Preface
Since the very first ages of aeronautics, the leading role of experimentation was immediately
clear. While Newton’s sine squared law to predict aerodynamic drag slowed down the rush
toward human flight for several decades, as it was used as an argument to support the impossi-
bility of designing high-lift low-drag devices, the enthusiasm and the experimental evidences
achieved in the eighteenth and nineteenth centuries contested the theory and paved the way
to the era of aeronautics. Starting from the historical moment of the first powered flight in
1903 on Kitty Hawk Beach, the role of the experimentation has never been disputed: on one
side the struggle to closely reproduce realistic flow conditions in controlled environment and
on the other side the commitment to extract the most complete and reliable information about
the flow—these have been the leading incentives for the continuous evolution of experimental
aerodynamics over the last century. The increasing availability of high-performance comput-
ers for computational fluid dynamics, which was expected to suppress experimentation with
relatively low-cost simulation if compared to the burden of extensive experimental test cam-
paigns, has the counter-effect of pushing toward more and more sophisticated experimental
techniques. The ubiquitous nature of turbulence, the limits of direct numerical simulation of
the Navier–Stokes equations at relatively large Reynolds numbers, and the urgent need to set
benchmarks for turbulence closure models validation provided an incomparable thrust to the
development of measurement tools.
We firmly believe that since experimental aerodynamics is a branch of science that is far
from fading, a well-rounded background of the next generation of specialists in aerodynamics
could not stand without a deep knowledge of current limits and potentialities of the experi-
mental techniques, as well as of the principles of real data characterization and treatment.
This belief originated the idea of this book directed to students in the final steps of their uni-
versity career. The ambitious task is to provide a panoramic view on the fundamentals of the
main measurement techniques while simultaneously keeping a weather eye on leading edge
research. This target pushed us toward the idea of including contributions from specialists of
the presented measurement techniques. The final consortium is composed of 13 contributors,
from continental Europe, Russia, and the United States, with active lines of research and
development in the discussed measurement techniques.
This book is divided into four main sections. Section I provides a general introduction to
the problem of measuring experimental quantities in aerodynamics. The scenario on the back-
ground relies on the fundamentals of the Navier–Stokes equations and on the flow properties
of interest (Chapter 1). In this section, the student is also made aware of a powerful tool for the
design of experiments such as dimensional analysis. Some rudiments on instruments for sta-
tistical data characterization (measurement uncertainty, statistical representation of turbulent
flow fields, etc.) are provided in Chapter 2. In this section, the student is also guided through
some tools for data processing, such as Fourier analysis, Proper Orthogonal Decomposition,
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viii PREFACE
and conditional averaging. Furthermore, since the experiment is in the first place an attempt to
reproduce flow conditions in controlled environment, an overview on wind tunnel facilities is
provided in Chapter 3. Eventually, as direct visualization used as an instrument to understand
the flow motion can be considered the dawn of experimental fluid mechanics, a place of honor
is reserved to flow visualization techniques (Chapter 4).
Section II focuses the attention on the measurement of scalar thermodynamic proper-
ties. Pressure measurements are commonly used to infer on other fluid dynamic properties,
such as wall shear stresses, fluid velocity, and more recently aeroacoustic noise sources. In
Chapter 5, the traditional methods based on static pressure tubes, wall tappings, and pressure-
sensitive paints are integrated with the most recent horizons opened by the advancements of
highly time-resolved measurements with microphones. Chapter 6 is focused on the methods
for punctual and surface temperature measurements. In this last case, particular attention is
devoted to full-field techniques for heat flux measurement. The section concludes with an
overview on density-based techniques (Chapter 7 and 8), which rely on index of refraction
changes along the optical path to outline features of the flow field. Even though these tech-
niques are well assessed as optical flow visualization methods, active research is ongoing on
the extraction of quantitative 3D information.
Section III is centered on velocity measurement techniques. In Chapter 9, the fundamen-
tals of thermal anemometry are described, as well as the most recent advancements with
respect to near-wall measurements. Chapter 10 covers the basics of optical laser velocimetry
methods, with utter focus on particle image velocimetry. Chapter 11 provides a panoramic
view of the most recent 3D velocimetry methods. The conceptual pathway underlying this
section is somehow twofold: on one side, the workhorses in turbulence investigation are pre-
sented, with their relative points of strength and weaknesses, and with some insights on future
years developments; and on the other side, the evolution of velocimetry toward results getting
closer and closer to that of numerical simulation (at least in the 4D format and in the declara-
tion of intents) is described.
Section IV closes the book with a description of methods to measure the effects of momen-
tum transfer from the flowing fluid to bodies immersed in it. The discussion in Chapter 12
covers the techniques for the measurement of wall shear stresses, which have fundamental
importance for the analysis of drag near a solid surface or for the study of wall turbulence.
Recent advances in measurement techniques such as oil film interferometry are also dis-
cussed. In Chapter 13, methods for the extraction of forces and moments are described. The
focus is on traditional invasive methods (balances, strain gauges, load cells, etc.) as well as on
the most recent developments on forces extraction from velocimetry data.
Editors
Stefano Discetti received his BSc (2007), MSc (2009), and PhD (2013) in aerospace
engineering from the University of Naples Federico II. His PhD thesis focused on the develop-
ment of tomographic PIV and its application to turbulent flows. As a part of his PhD studies,
in 2010 and 2012 he worked in the Laboratory for Energetic Flow and Turbulence at Arizona
State University on the development of 3D particle image velocimetry for the investigation of
the turbulence generated by fractal grids. After receiving his PhD, he joined the Department
of Bioengineering and Aerospace Engineering at Universidad Carlos III de Madrid where he
currently holds a visiting professorship in the area of experimental aerodynamics and propul-
sion. He also served as test-case provider and referee in the team of the 4th International PIV
Challenge. His research interests include development of non-intrusive measurement tech-
niques, unsteady aerodynamics and wall-bounded turbulent flows.
Andrea Ianiro received his BSc (2006), MSc (2008), and PhD (2012) in aerospace engineer-
ing from the University of Naples Federico II. His PhD was on nonintrusive diagnostics on
impinging jets with IR thermography and tomographic PIV. During his PhD studies, in 2010
and 2011 he joined the Aerodynamics Labs at TU Delft for the development of tomographic
PIV measurements on impinging jets. After receiving his PhD, Dr. Ianiro worked as a postdoc-
toral research fellow at the University of Naples developing tomographic PIV diagnostics for
swirl flows in geometries representative of aero engine combustors. In 2013, Dr. Ianiro joined
the Department of Bioengineering and Aerospace Engineering at Universidad Carlos III de
Madrid where he currently is a visiting professor, teaching courses on aero engines and exper-
imental aerodynamics. His research interests include wall-bounded flows, unsteady aerody-
namics, and reduced order modeling techniques.
ix