Spelling suggestions: "subject:"aeronautical engineering"" "subject:"aeronautical ingineering""
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Development Of A Comprehensive And Modular Modelling, Analysis And Simulation Tool For HelicoptersYucekayali, Arda 01 September 2011 (has links) (PDF)
Helicopter flight dynamic, rotor aerodynamic and dynamic analyses activities
have been a great dispute since the first helicopters, at both design and test stages.
Predicting rotor aerodynamic and dynamic characteristics, helicopter dynamic
behavior and trimmed flight conditions is a huge challenge to engineers as it
involves the tradeoff between accuracy, fidelity, complexity and computational cost.
Flight dynamic activities such as / predicting trim conditions, helicopter
dynamic behavior and simulation of a flight condition or maneuver mostly require
analysis tools with low computational cost and complexity. However this decreases
accuracy and fidelity of the model. On the other hand, analyses at design stages,
such as / blade geometric and structural design mostly requires accurate and higher
fidelity aerodynamic load predictions over the rotor disk. Contrarily this brings high
computational cost and complexity. Therefore separate analysis tools for each
objective or one complete tool that can be used for all purposes are essential.
Throughout this study a helicopter mathematical including trim model with a
selective and modular structure is developed as a generic analysis tool. The
selective structure enables the mathematical model to be used in both flight dynamic
and comprehensive analysis while the modular structure plays a role as an
infrastructure for further developments. The mathematical model developed is
validated with flight test data of several helicopters. Besides, commercial helicopter
comprehensive analysis tools are used to validate the mathematical model
analyses. Results showed good agreement with the compared data.
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Analysis And Design Of Helicopter Rotor Blades For Reduced Vibrational LevelTamer, Aykut 01 September 2011 (has links) (PDF)
In this thesis analysis and design of helicopter rotor blades were discussed for reduced
vibrational level. For this purpose an optimization procedure was developed which involves
coupling of the comprehensive rotorcraft analysis tool CAMRAD JA and the gradient based
optimization algorithm. The main goal was to achieve favorable blade structural dynamics
characteristics that would lead to reduction in vibrational level. For this purpose blade
stiffness and mass distributions were considered as the design variables. In order to avoid
likely occurrences of unrealistic results, the analyses were subjected to constraints which
were sensitive to the design variables. The optimization procedure was applied on two
isolated rotor blades and a full helicopter with main rotor, tail rotor and fuselage by using
natural frequency separation and hub load minimization respectively. While the former
approach relied on the blade natural frequencies, the latter approach involved higher
harmonic aerodynamic and blade motion calculations. For both approaches, the
improvement in vibration characteristics and blade mass and stiffness distributions of the
initial design and the design after optimization analyses were compared and discussed.
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Particle Filter Based Track Before Detect Algorithm For Tracking Of Dim Moving TargetsSabuncu, Murat 01 February 2012 (has links) (PDF)
In this study Track Before Detect (TBD) approach will be analysed for tracking of dim moving
targets. First, a radar setup is presented in order to introduce the radar range equation and
signal models. Then, preliminary information is given about particle filters. As the main
algorithm of this thesis, a multi-model particle filter method is developed in order to solve
the non-linear non-Gaussian Bayesian estimation problem. Probability of target existence
and RMS estimation accuracy are defined as the performance parameters of the algorithm for
very low SNR targets. Simulation results are provided and performance analysis is presented
as a conclusion.
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Determination Of Prying Load On Bolted ConnectionsAtasoy, Mert 01 February 2012 (has links) (PDF)
Analysis of aircraft structures are mainly performed by assuming that the structure behaves
linearly. In linear finite element analysis, it is assumed that deformations are small, thus
geometric nonlinearity can be neglected. In addition, linear analysis assumes that linear constitutive
laws applicable, implying that material nonlinearity can also be neglected. One very
common type of nonlinearity is associated with the boundary conditions. Contact between
two deformable bodies or between a deformable and rigid body are typical examples of nonlinearity
associated with boundary conditions. Linear structural analysis, in general, does
not include contact analysis. Simplicity of linear analysis in terms modeling, interpreting the
results and solution time makes the linear analysis approach very convenient in preliminary
design and analysis stage of aircraft structures. However, simplicity of linear analysis may
result in unconservative results which may occur due to neglecting the true nonlinear behavior
of the structure. In this thesis, one such nonlinear eect called prying load eect on the
tensile connections is studied. The eect of prying load on structures are initially described
by referencing the analytical approaches presented in the literature. Finite element models of
typical bolted connections such as L and T type are generated for various combinations of the
chosen design parameters such as bolt diameter, flange thickness, washer diameter and edge
distances. Parametric modeling approach is used to perform the high number of finite element analysis which involve contact for the purpose of calculating the prying load. Comparative
study of the eect of prying load is then conducted by also including the results presented
in the literature. Comparisons of the prying load are done with the experimental results presented
in the literature. Series of finite element analyses are preformed for various cases such
that eect of geometrical variables and bolt preload on prying ratio can be understood. According
to the results obtained, it is concluded that main factors eecting the prying ratio are
the distance of bolt center to the clip web, flange thickness of the clip and preload on the bolt
where the eect of edge distance of the bolt is insignificant.
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Conceptual Internal Design And Computational Fluid Dynamics Analysis Of A Supersonic InletAlemdaroglu, Mine 01 May 2005 (has links) (PDF)
ABSTRACT
CONCEPTUAL INTERNAL DESIGN AND COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF A SUPERSONIC INLET
ALEMDAROgLU, Mine
M. S., Department of Aerospace Engineering
Supervisor: Prof. Dr. Yusuf Ö / ZYÖ / RÜ / K
May 2005, 144 pages
In this thesis, the conceptual internal design of the air inlet of a supersonic, high altitude, solid propellant ramjet cruise missile is performed. Inviscid, compressible CFD analysis of the designed inlet is made in order to obtain qualitative and quantitative performance characteristics of the inlet at different operating conditions.
The conceptual design of the inlet is realized by using analytical relations and equations, correlations derived from numerous available past experimental data and state-of-the-art design examples. The performance estimation of the designed inlet at different operating conditions is done by using one and two dimensional gas dynamics equations. The results of the performance estimation study are compared with the results of the CFD analysis and these results are discussed in detail. A commercial tool, CFD-FASTRANÒ / , is used for the CFD analysis. Inlet flow phenomena such as, different shock patterns and shock positions, performance degradation at off-design operating conditions and inlet unstart are observed.
Keywords: Supersonic Inlet, Ramjet, CFD, Inlet Performance Characteristics, Operating Conditions, Unstart
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Numerical And Experimental Analysis Of Flapping Motion In Hover. Application To Micro Air Vehicles.Kurtulus, Dilek Funda 01 June 2005 (has links) (PDF)
The aerodynamics phenomena of flapping motion in hover are considered in view of
the future Micro Air Vehicle applications. The aim of this work is to characterize the
vortex dynamics generated by the wing in motion using direct numerical simulation
and experimental analysis then to propose a simplified analytical model for
prediction of the forces in order to optimize the parameters of the motion leading to
maximum force. A great number of cases are investigated corresponding to different
angles of attack, location of start of change of incidence, location of start of change
of velocity, axis of rotation, and Re number. The airfoil used is symmetrical. The
flow is assumed to be incompressible and laminar with the Reynolds numbers
between 500 and 2000. The experimental results obtained by the laser sheet
visualization and the Particle Image Velocimetry (PIV) techniques are used in
parallel with the direct numerical simulation results for the phenomenological
analysis of the flow. The model developed for the aerodynamic forces is an indicial method based on the use of the Duhamel Integral and the results obtained by this
model are compared with the ones of the numerical simulations.
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Evaluation Of A New Turbulence Model For Boundary Layer Flows With Pressure GradientMarangoz, Alp 01 August 2005 (has links) (PDF)
In this thesis, a new turbulence model developed previously for channel and flat plate flows is evaluated for flat plate flows with pressure gradient. For this purpose a flow solver, which uses boundary layer equations as the governing equations and Von Karman momentum integral equation for the calculation of skin friction, is developed.
It is shown that the error of the new turbulence model, in predicting the velocity profile, is less than 5 % for the flat plate flows without pressure gradient and less than 10 % for the flat plate flows with favorable pressure gradient. It is also shown that results with an error in the order of 20 % can be achieved for the flat plate flows with adverse pressure gradient.
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Development Of A Wing Design Tool Using Euler/navier-stokes Flow SolverUlker, Kivanc 01 December 2005 (has links) (PDF)
A three dimensional wing design tool with analysis functions has been
developed with embedded Euler/Navier-Stokes flow solver and a three
dimensional hyperbolic grid generator. A graphical user interface has
been constructed using PYTHON script language and the tool was
enhanced with pre-processing and post-processing capabilities. Analysis
and design procedures are demonstrated with automatic grid generation,
automatic series solution and automatic graphs and reports generation.
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A Tool For Designing Robust Autopilots For Ramjet MissilesKahvecioglu, Alper 01 February 2006 (has links) (PDF)
The study presented in this thesis comprises the development of the longitudinal autopilot algorithm for a ramjet powered air-to-surface missile. Ramjet Missiles have short time-of-flight, however they suffer from limited angle of attack margins due to poor operational-region characteristics of the ramjet engine. Because of such limitations and presence of uncertainties involved, Robust Control Techniques are used for the controller design. Robust Control Techniques not only provide an easy limitation/uncertainty/performance handling for MIMO systems, but also, robust controllers promise stability and performance even in the presence of uncertainties of a pre-defined class. All the design process is carried out in such a way that at the end of the study a tool has been developed, that can process raw aerodynamic data obtained by Missile DATCOM program, linearize the equations of motion, construct the system structure and design sub-optimal H& / #8734 / controllers to meet the requirements provided by the user. An autopilot which is designed by classical control techniques is used for performance and robustness comparison, and a non-linear simulation is used for validation. It is concluded that the code, which is very easy to modify for the specifications of other missile systems, can be used as a reliable tool in the preliminary design phases where there exists uncertainties/limitations and still can provide satisfactory results while making the design process much faster.
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Dynamical stability of aeroplanes (with three plates)Hunsaker, Jerome C. (Jerome Clarke), 1886-1984, Huff, T. H, Douglas, Donald W. 1892-1981, Chow, Hou Kun, Clark, Virginius Evans, 1866- January 1916 (has links)
Thesis: Sc. D., Massachusetts Institute of Technology. Department of Aeronautical Engineering, 1916. / MIT Institue Archives Thesis Coll.: copy is the Smithsoniam Institution publication. / Publication 2414. Hodgkins fund. Originaly prepared by Hunsaker as his Eng. D. Thesis, Massachusetts Institute of Technology, Dept. of Aeronautical Engineering, 1916. According to the MIT Registrar's Office, this degree was changed to an Sc.D., 1923 June 12. Original thesis did not contain the three plates. / by Jerome C. Hunsaker ... assisted by T. H. Huff, S. B., D. W. Douglas, S. B., H. K. Chow, S. M., and V. E. Clark. / Sc. D.
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