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Fluid mechanical aspects of separated and vortical flow in aircraft
wing aerodynamics are treated. The focus is on two wing classes:
(1) large aspect-ratio wings and (2) small aspect-ratio delta-type
wings. Aerodynamic design issues in general are not dealt with.
Discrete numerical simulation methods play a progressively larger
role in aircraft design and development. Accordingly, in the
introduction to the book the different mathematical models are
considered, which underlie the aerodynamic computation methods
(panel methods, RANS and scale-resolving methods). Special methods
are the Euler methods, which as rather inexpensive methods embrace
compressibility effects and also permit to describe lifting-wing
flow. The concept of the kinematically active and inactive
vorticity content of shear layers gives insight into many flow
phenomena, but also, with the second break of symmetry---the first
one is due to the Kutta condition---an explanation of lifting-wing
flow fields. The prerequisite is an extended definition of
separation: "flow-off separation" at sharp trailing edges of class
(1) wings and at sharp leading edges of class (2) wings. The
vorticity-content concept, with a compatibility condition for
flow-off separation at sharp edges, permits to understand the
properties of the evolving trailing vortex layer and the resulting
pair of trailing vortices of class (1) wings. The concept also
shows that Euler methods at sharp delta or strake leading edges of
class (2) wings can give reliable results. Three main topics are
treated: 1) Basic Principles are considered first: boundary-layer
flow, vortex theory, the vorticity content of shear layers, Euler
solutions for lifting wings, the Kutta condition in reality and the
topology of skin-friction and velocity fields. 2) Unit Problems
treat isolated flow phenomena of the two wing classes. Capabilities
of panel and Euler methods are investigated. One Unit Problem is
the flow past the wing of the NASA Common Research Model. Other
Unit Problems concern the lee-side vortex system appearing at the
Vortex-Flow Experiment 1 and 2 sharp- and blunt-edged delta
configurations, at a delta wing with partly round leading edges,
and also at the Blunt Delta Wing at hypersonic speed. 3) Selected
Flow Problems of the two wing classes. In short sections practical
design problems are discussed. The treatment of flow past
fuselages, although desirable, was not possible in the frame of
this book.
This modern text presents aerodynamic design of aircraft with
realistic applications, using CFD software and guidance on its use.
Tutorials, exercises, and mini-projects provided involve design of
real aircraft, ranging from straight to swept to slender wings,
from low speed to supersonic. Supported by online resources and
supplements, this toolkit covers topics such as shape optimization
to minimize drag and collaborative designing. Prepares seniors and
first-year graduate students for design and analysis tasks in
aerospace companies. In addition, it is a valuable resource for
practicing engineers, aircraft designers, and entrepreneurial
consultants.
The last decade has seen a dramatic increase of our abilities to
solve numerically the governing equations of fluid mechanics. In
design aerodynamics the classical potential-flow methods have been
complemented by higher modelling-level methods. Euler solvers, and
for special purposes, already Navier-Stokes solvers are in use. The
authors of this book have been working on the solution of the Euler
equations for quite some time. While the first two of us have
worked mainly on algorithmic problems, the third has been concerned
off and on with modelling and application problems of Euler
methods. When we started to write this book we decided to put our
own work at the center of it. This was done because we thought, and
we leave this to the reader to decide, that our work has attained
over the years enough substance in order to justify a book. The
problem which we soon faced, was that the field still is moving at
a fast pace, for instance because hyper sonic computation problems
became more and more important."
This is one in a series of workshops organized by the GAID1
Specialist Group for Numerical Methods in Fluid Hechanics
(GAMM-Fachausschuss flir Numerische Hethoden in der Stromungs-
mechanik) whose purpose is to bring together the small group of
researchers actively working on a sharply defined topic in order to
discuss in detail their problems and experiences, to promote direct
comparison and critical evaluation of algorithms, and to stimulate
new ideas for numerical methods in fluid dynamics. The chairmen of
this workshop were A. Rizzi of FFA, Sweden, and H. Viviand of
ONERA, France. 2. INTRODUCTION Practically ten years have passed
since it was first demonstrat- ed that the nonlinear potential
equation of mixed type which governs inviscid transonic flow could
be solved in a numerical procedure. These years have seen an
interest in the computation of transonic flow that continues to
grow because of the develop- ing and ever-increasing ability of the
numerical methods to solve more and more complex flows and because
of the great practical use to which their solutions can be put.
From the question of whether we can solve the equations of
transonic flow we have now progressed to the question of how
accurately can we solve them. Any attempt to answer it must by
necessity include a collective comparison of the results obtained
from the com- putational methods that are being applied today for
the numerical solution of inviscid steady transonic flow.
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