Numerical Simulation of the Aerodynamics of High Lift Configurations

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Numerical Simulation of the Aerodynamics of High Lift Configurations


Wing loading has been increased as a result of a combination of higher cruise
speeds and aerodynamic efficiency but with adverse effects on stall speeds. At the
same time, the length of the airports’ runaways cannot be increased due to economic
reasons, in addition to the fact that the speeds of takeoff and landing are
limited to satisfy safety standards. It is in this context in which the importance of
high-lift devices for commercial aerodynamic applications comes into play.
The design of high-lift devices is focused on simpler systems to maximize the lift
and reduce maintenance costs. The aerodynamic design of these devices is
restricted by takeoff and landing distances, safe speeds during landing and takeoff
and climb rates. All these operational parameters impose restrictions on aerodynamic
properties such as the lift coefficient (CL), lift-to-drag ratio (L/D) and stall
angle of attack. In recent years, numerical simulations have played an important
role in the prediction of these aerodynamics properties. As an example, NASA and
the American Institute of Aeronautics and Astronautics (AIAA) have organized
three events related to the application of numerical simulations in the prediction
of the aerodynamic properties of high-lift configurations since 2010. I have personally
participated in these events, called High-Lift Prediction Workshop
(HiLiftPW), and in general the conclusion is that the problem of correctly estimating
the turbulent and separated flow near CLmax is still an important challenge
for modern computational codes and software. Also, there is still a need to develop
reliable turbulence models for this application, and the computational cost of these
simulations is considerable, given the fact that finer meshes (around 200-M cells)
are needed to reduce the deviation of the numerical solution between the various
different codes and softwares. Numerical results consistently show that CL is typically
under-predicted, as well as are the drag and the magnitude of the pitching
moment. In this context, this book is devoted to gathering some of the results of the
most recent version of the HiLiftPW that was held in June 2017.
This book has six chapters dedicated to the numerical simulations of high-lift
configurations and specifically all of them that are related to full Navier–Stokes
(NS) solvers. This means that the numerical and computational techniques used for
these contributions are based on Computational Fluid Dynamics (CFD). All the
chapters discuss numerical solutions of the high-lift system proposed for the third
HiLiftPW held in Denver in June 2017. All the chapters show numerical solutions
for the aerodynamic properties of the models studied and comparisons (validation)
with experimental data when available.
The first chapter is a review of high-lift configurations in order to provide a
context for the book. This chapter also shows some results of the simulation of the
flow around the High-Lift Common Research Model (HLCRM), which was one
of the models introduced in the last HiLiftPW. These results are briefly introduced
only to give some insight to the reader about the physics of the turbulent flow
around these devices. The second chapter is dedicated to the topic of grid generation
of high-lift configurations for CFD simulations. Typically, this is not a topic
deeply discussed in textbooks or technical articles, so I personally consider that this
contribution helps to give a better idea of the challenges and main features that need
to be considered when facing such a complex problem. One of the interesting topics
in this chapter is the discussion of the guidelines given by the AIAA on grid
generation for high-lift systems. The third, fourth and fifth chapters are all dedicated
to numerical computations of the Japanese Aerospace Exploration Agency (JAXA)
Standard Model (JSM), using three different CFD solvers and simplifications of the
governing equations. For example, Chapter “Incompressible Solutions About High-
Lift Wing Configurations” is devoted to the use of an incompressible flow solver.
The conclusions reached and observations made in this chapter are quite interesting
since one of the main requirements of the HiLiftPW is to use fully compressible NS
solvers for the simulations. Chapter “Numerical Investigations of the Jaxa High-Lift
Configuration Standard Model with MFlow Solver” deals with the numerical
solution of the JSM using a fully compressible NS solver; a very interesting topic
discussed in this chapter is the High-Performance Computing (HPC) resources
needed and the estimation of efficiency for performance in parallel computation for
this kind of simulation. In Chapters “Incompressible Solutions About High-Lift
Wing Configurations” and “Numerical Investigations of the Jaxa High-Lift
Configuration Standard Model with MFlow Solver”, computations are performed
using the Finite Volume (FV) method which is the standard way to discretize the
governing equations. Nevertheless, in Chapter “Time-Resolved Adaptive Direct
FEM Simulation of High-Lift Aircraft Configurations”, the numerical method used
for computing the solution of the flow is the Finite Element Method (FEM). Since I
read the book “Computational Turbulent Incompressible Flow” by Professor
Hoffman in 2007, I have been intrigued by the capabilities of the FEM proposed in
that book. In Chapter “Time-Resolved Adaptive Direct FEM Simulation of High-
Lift Aircraft Configurations”, this question is solved by showing the efficiency
of the solver based on this methodology and its advantages in comparison with
other numerical techniques typically used in CFD. Finally, Chapter “RANS
Simulations of the High Lift Common Research Model with Open-Source Code
SU2” deals with the numerical solution of the flow around the HLCRM using an
open-source code called SU2. This final chapter also uses an FV method for solving
the fully compressible NS equations.
It is expected that this book can serve as a reference for graduate students, as
well as researchers in the field of CFD applied to the aerodynamics of high-lift
configurations. Designers and engineers from the aeronautical industry may also
benefit from the content of the book as it provides the state-of-the-art in CFD
computations applied to the prediction of aerodynamic properties of high-lift
configurations, as well as flow characteristics. We hope that the way the book is
organized helps the reader to find a specific topic of interest and to engage the
reader as he/she goes from one section to the next one. Finally, I would like to
acknowledge the help of Dr. Rumsey and Dr. Slotnick during the 3rd HiLiftPW for
helping me in the realization of this project.


Review on High-Lift Systems for Aerodynamic Applications . . . . . . . . . 1
A. Matiz-Chicacausa and C. A. Sedano
Grid Generation About High-Lift Wing Configurations . . . . . . . . . . . . . 9
Nirajan Adhikari and D. Stephen Nichols
Incompressible Solutions About High-Lift Wing Configurations . . . . . . 27
Nirajan Adhikari and D. Stephen Nichols
Numerical Investigations of the Jaxa High-Lift Configuration
Standard Model with MFlow Solver . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Jiangtao Chen, Jian Zhang, Jing Tang and Yaobing Zhang
Time-Resolved Adaptive Direct FEM Simulation of High-Lift
Aircraft Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Johan Jansson, Ezhilmathi Krishnasamy, Massimiliano Leoni,
Niclas Jansson and Johan Hoffman
RANS Simulations of the High Lift Common Research Model with
Open-Source Code SU2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
A. Matiz-Chicacausa, J. Escobar, D. Velasco, N. Rojas and C. Sedano