CFD simulation of the developing boundary layer in an atmospheric wind tunnel

Download

index.pdf

Date

2018

Author

Kıran, Defne

Metadata

Show full item record

Item Usage Stats

251
views

101
downloads

Structural coupling methods are widely used in predicting dynamics of coupled systems. In this study, the reverse problem, i.e. predicting the dynamic behavior of a particular subsystem from the knowledge of the dynamics of the overall system and of all the other subsystems, is studied. This problem arises when a substructure cannot be measured separately, but only when coupled to neighboring substructures. The dynamic decoupling problem of coupled linear structures is well investigated in literature. However, decoupling of coupled structures that include a nonlinear element such as clearance, friction and nonlinear stiffness still remains untouched. In this thesis, firstly, decoupling techniques for coupled linear structures are investigated. Two new methods for decoupling of coupled linear systems are introduced and their performances were compared to those of the best decoupling methods known in literature. Then, the dynamic decoupling problem of coupled nonlinear structures is considered for the first time. A method is developed for calculating FRFs of a substructure decoupled from a coupled nonlinear structure involving any type of nonlinearity that can be modelled as a single nonlinear element. Depending on where the nonlinear element is, i.e., either in the known or unknown substructure, or at the connection, the formulation differs. Firstly, applications of the method are demonstrated on nonlinear lumped parameter systems using simulated experimental data. Then, real-life applicability of the proposed method is shown through two nonlinear experimental test structures. Finally, the method is applied on a real-life engineering problem in order to demonstrate its performance.

Subject Keywords

Wind tunnels., Boundary layer., Computational fluid dynamics.

URI

http://etd.lib.metu.edu.tr/upload/12621994/index.pdf
https://hdl.handle.net/11511/27205

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

CFD analysis of missile shroud separation Çeliker, Hasan Erkan; Eyi, Sinan; Department of Aerospace Engineering (2015) In this thesis, shroud separation on generic missile is performed by using the Computational Fluid Dynamics (CFD). This study is divided into two main parts. In the first part, aerodynamic coefficients of generic missile are calculated and store separation is performed. Additionally, the numerical analyses results are compared respectively with the experimental results in order to validate of CFD analyses method. Three-dimensional steady/unsteady Navier-Stokes equations are solved and three different turbul...
Investigation of decoupling techniques for linear and nonlinear systems Kalaycıoğlu, Taner; Özgüven, Hasan Nevzat; Department of Mechanical Engineering (2018) Structural coupling methods are widely used in predicting dynamics of coupled systems. In this study, the reverse problem, i.e. predicting the dynamic behavior of a particular subsystem from the knowledge of the dynamics of the overall system and of all the other subsystems, is studied. This problem arises when a substructure cannot be measured separately, but only when coupled to neighboring substructures. The dynamic decoupling problem of coupled linear structures is well investigated in literature. Howev...
Application of fully implicit coupled method for 2D incompressible flows on unstructured grids Zengin, Şeyda; Tarman, Işık Hakan; Department of Engineering Sciences (2012) In the subject of Computational Fluid Dynamics (CFD), there seems to be small number of important progress in the pressure-based methods for several decades. Recent studies on the implicit coupled algorithms for pressure-based methods have brought a new insight. This method seems to provide a huge reduction in the solution times over segregated methods. Fully implicit coupled algorithm for pressure-based methods is very new subject with only few papers in literature. One of the most important work in this a...
Application of spring analogy mesh deformation technique in airfoil design optimization Yang, Yosheph; Özgen, Serkan; Department of Aerospace Engineering (2015) In this thesis, an airfoil design optimization with Computational Fluid Dynamics (CFD) analysis combined with mesh deformation method is elaborated in detail. The mesh deformation technique is conducted based on spring analogy method. Several improvements and modifications are addressed during the implementation of this method. These enhancements are made so that good quality of the mesh can still be maintained and robustness of the solution can be achieved. The capability of mesh deformation is verified by...
Frequency dependence of the constitutive parameters of causal perfectly matched anisotropic absorbers Kuzuoğlu, Mustafa (1996-12-01) Perfectly matched layers (PML's), which are employed for mesh truncation in the finite-difference time-domain (FDTD) or in finite element methods (FEM's), can be realized by artificial anisotropic materials with properly chosen permittivity and permeability tensors. The tensor constitutive parameters must satisfy the Kramers-Kronig relationships, so that the law of causality holds. These relations are used to relate the real and imaginary parts of the constitutive parameters of the PML media to deduce the a...

Citation Formats

D. Kıran, “CFD simulation of the developing boundary layer in an atmospheric wind tunnel,” M.S. - Master of Science, Middle East Technical University, 2018.