Table Of ContentSpringerBriefs in Applied Sciences and Technology
Peijian Lv
Power-Based Study of
Boundary Layer Ingestion
for Aircraft Application
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Peijian Lv
Power-Based Study
of Boundary Layer Ingestion
for Aircraft Application
Peijian Lv
School of Aerospace Engineering
Beijing Institute of Technology
Beijing, China
ISSN 2191-530X ISSN 2191-5318 (electronic)
SpringerBriefs in Applied Sciences and Technology
ISBN 978-981-19-5496-2 ISBN 978-981-19-5497-9 (eBook)
https://doi.org/10.1007/978-981-19-5497-9
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To my family
Preface
This book presents research on boundary layer ingestion (BLI). BLI is an unconven-
tional aircraft–engine integration technique which aims at integrating the aircraft and
the propulsion system such that the overall aircraft fuel consumption can be reduced.
This research begins with a literature survey on propulsion integration. The liter-
ature is not only limited to recent work on novel aircraft concepts utilizing BLI but
also covers the previous studies on ship propellers and pusher propellers used for
aircraft. Various studies in the literature show that BLI and/or similar configura-
tions can effectively reduce the total power consumption of the propulsion system.
However, discrepancies can be identified among various research with respect to the
improvements that BLI could provide in terms of reduction in the power consumption.
Different research methods have been used to investigate and study this phenomenon
in the literature. In particular, the various research methods give an indication that
the physics involved in BLI might not be well understood. As a result, the current
research aims to enhance the fundamental understanding of BLI. The main research
questions are identified below:
• What are the mechanisms of BLI for the provided benefit?
• How large is the benefit of BLI?
This study addresses the aforementioned questions by following a research line
where power conversion is the key to explaining the mechanisms of BLI . The
current research consists of three main pillars, namely theoretical analysis, numer-
ical simulation, and experimental study. In the theoretical analysis, the physical
model for understanding BLI is developed. Numerical simulations and experimental
study provide validations to the developed model and assist in understanding the
phenomenon involved with BLI.
In the theoretical analysis, effort is made to evaluate the performance of the
propulsor and its associated fuselage in two configurations, namely the so-called
BLI configuration and the wake ingestion (WI) configuration. A power conversion
analysis uses power balance method (PBM) introduced by Drela to elaborate the
power-saving mechanism of WI, showing that the Froude’s propulsive efficiency
vii
viii Preface
as a figure of merit should be separated from the power conversion efficiency in
these configurations. The body/propulsor interaction occurring in the BLI config-
uration is qualitatively analyzed to clarify its influence on the performance of the
integrated vehicle. The results suggest that the minimization of total power consump-
tion should be used as a design criterion for aircraft utilizing BLI rather than focusing
on minimization of drag, as is generally done.
The numerical simulations are considered as an extension of the theoretical anal-
ysis to support the physical understanding of BLI elaborated in the developed theoret-
ical model. This simulation study has two major objectives: establishing the process
of typical power conversions and quantifying the influences of BLI on the power
conversion of the theoretical model. To achieve these objectives, this study on power
conversion processes is rather limited to simple cases, which help to decipher the
processes easily, and these cases bring out the key elements involved in the power
conversion process elegantly. Therefore, the simulation is limited to 2D steady incom-
pressible flows, which excludes complicated flow physics, such as compressibility.
This simplification allows the analysis to be focused on the mechanisms elaborated
in the theoretical analysis. In this simulation study, only typical models are used and
the simulation results are processed using the PBM. The results prove that BLI could
increase the profile drag of a body but reduce the actual total power consumption.
The experimental study aims to provide evidence to the physical understanding
of BLI developed during the theoretical analysis. This study focuses on the power
conversion processes involved in a propulsor operating in the wake of the body.
The experimental set-up is specifically designed such that the same propulsor can
ingest a body wake or purely work in the freestream. Conventional force balance
measurement techniques are used to measure the thrust and power in the experi-
ments. Stereoscopic PIV is employed in order to visualize the flow and understand
the physics involved in BLI and WI. This technique has been used for the first time
to visualize the flow in wake ingesting propellers. Furthermore, the PBM is used to
quantify the power conversion mechanisms using the data obtained from the experi-
ments. The results prove that the dominant mechanism responsible for the efficiency
enhancement in this experimental study is due to the utilization of body wake energy
by the wake ingesting propeller.
Finally, efforts are made to summarize the main findings of the three pillars.
These methods are theoretical analysis, numerical simulation, and experimental
study, respectively. A key working principle encompassing the entire research is
extracted. The conclusion of this research provides answers to the research ques-
tions raised in the earlier chapters of this book, and recommendations for future
research are provided.
Overall, the importance of wake energy flow rate in understanding BLI and
WI phenomenon is highlighted. This understanding is a major milestone in the
research into this phenomenon. In terms of the results, this research agrees with
several previous investigations which claim that BLI could effectively reduce power
consumption of the aircraft.
Beijing, China Peijian Lv
Acknowledgements
I would like to thank China Scholarship Council (CSC) for the financial support
which allows me to do Ph.D. research in TU Delft. The CSC scholarship makes my
dream become true: to do the most exciting research in a top university.
I would like to express my gratitude to my promotor Prof. Leo Veldhuis. You
are always kind, and it is a pleasure to work with you. I have been inspired by your
enthusiasm in aviation since our first meet. In the wind tunnel test, you provided
many wise suggestions which are valuable and helpful. Moreover, you encouraged
me when I feel frustrated in writing this book and your encouragements support me
going through difficult times.
Dr. Arvind G. Rao, please accept my deepest appreciation! As my co-promotor,
you graciously accept me as a PhD candidate and you have made enormous amount
of efforts to guide me in research. I feel proud that your efforts are paying back. I
would like to thank you for the assistance in finalizing this book. Your high standard
is impressive, and it was a great experience to work with you!
I would like to thank Prof. Georg Eitelberg. It is an honour to work with you. You
played a special role in inspiring me with research work. Especially, you challenged
me with truly tough questions. This gives me a chance to rethink my work profoundly.
I consider those challenges as touch stones which sharp my mind, and these will
benefit me in the rest part of my career. Thank you!
This research work will not be completed without the support of Dr. Dani Ragni.
Our collaboration in wind tunnel test and journal papers is productive. I would like
to thank graduate students Tarik Hartuç and Nando van Arnhem, and it was of great
joy to work with you! I could not forget the day Tarik and I shout out loudly in
the wind tunnel when we got the exciting results. Nando presented very impressive
work to help me understand my research better, and you are very kind to translate
the summary of this book into Dutch.
I would like to give thanks to my office mate and friend Mo Li. We had so many
great times in discussing aircraft, and we enjoyed our first glider flight together. It
is of great joy to work with my colleagues and friends in the FPP group, Yannian
Yang, Dipanjay Dewanji, Feijia Yin, Qingxi Li, Haiqiang Wang, Mark Voskuijl,
ix
x Acknowledgements
Tomas Sinnige, and André Perpignan. It is your companionship makes my life in the
Netherlands rich and colourful.
Last but not least, my parents Giexiang Lv and Xunfeng Feng, your love supports
me through the good and bad times. I can always get inspirations from you and
I feel lucky to be your son. My beloved wife Jingjing Yang, it is your love and
encouragement that supported me in finalizing this book. Thank you!
