An experimental investigation of the effects of spherical roughness elements on transition and boundary layer development.

Yeğen, İmdat


Development and evaluation of new bleed boundary condition models for supersonic inlet boundary layer bleed flow
Akar, Gökhan; Eyi, Sinan; Department of Aerospace Engineering (2019)
Shock wave/boundary layer interaction is an important issue that should be considered when studying supersonic inlet design for air vehicles. Porous bleed systems have traditionally been used for increase stability and efficiency of the supersonic inlets by means of removing the lower momentum part of the boundary layer to prevent flow separation caused by adverse pressure gradient. However, evaluating and determining the effect of the boundary layer bleed system on the performance of the supersonic inlet i...
An Experimental study on boundary layer separation control over s809 airfoil using synthetic jet actuators
Gül, Melika; Akmandor, İbrahim Sinan; Uzol, Oğuz; Department of Aerospace Engineering (2013)
This thesis presents the results of an experimental study that investigates the effect of periodic excitation from individually controlled synthetic jet actuators on the separated shear layer and wake of a model wing that has S809 airfoil profile. The synthetic jet array consists of three individually controlled synthetic jet actuators driven by piezoelectric diaphragms located at 28% chord location near the middle of the span of the blade. In the first part of the study, hot wire and surface pressure measu...
Experimental study of wave characteristics on a thin layer of de/anti-icing fluid
Özgen, Serkan; Sarma, GSR (2002-10-01)
Several series of experiments were conducted in order to investigate wave formation and wave characteristics on a thin layer of de/anti-icing fluid using a nonintrusive technique. The configuration consists of a thin layer of de/anti-icing fluid deposited on the lower wall of the wind tunnel section, sheared by a turbulent airflow. Beyond a critical value of the wind speed, two-dimensional surface waves could be observed. The characteristics of these waves like the wavelength and the wave speed could be mea...
Investigation of inviscid shear layer by linear stability theories
Topbaş, Ahmet Emre; Özgen, Serkan; Department of Aerospace Engineering (2018)
ThisIn this thesis, spatial and temporal instabilities of the inviscid shear layer flows are investigated using the linear stability theory. Utilizing the small and wavy disturbances, Rayleigh equation was derived from the Helmholtz vorticity equation. For the hyperbolic-tangent velocity profile, the Rayleigh equation was solved by using space and time amplification approaches by an in-house Fortran code involving RK4 and simplex method algorithm. Eigenvalues of various disturbance frequencies were calculat...
A comparative case study on school management practices in the United States and Turkey
Silman, Fatoş; Şimşek, Hasan; Department of Educational Sciences (2005)
This study aimed to comparatively examine school management practices in the US and Turkey in light of the two distinct administrative paradigms:Anglo-Saxon and Napoleonic traditions. In this study, a comparative case study method was used. The study was conducted in a basic education school (grades 1-8) in Ankara, Turkey, and in an elementary school (K-5) in Madison, the capital city of the state of Wisconsn, US. The sample contained 13 teachers and 4 administrators in the Turkish case, and 10 teachers and...
Citation Formats
İ. Yeğen, “An experimental investigation of the effects of spherical roughness elements on transition and boundary layer development.,” Ph.D. - Doctoral Program, Middle East Technical University, 1982.