Faculty of Aeronautics and Astronautics / Havacılık ve Uzay Bilimleri Fakültesi
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/551
2024-03-29T05:29:33ZDynamic response of filament winding angle on complex shaped mandrels
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4145
Dynamic response of filament winding angle on complex shaped mandrels
Torun, Ahmet Refah
Aerodynamic parts such as rocket nose and heat shield related composites are mainly produced with filament winding machines. Winding angle of the reinforcement filament is the main parameter to determine the thermomechanical properties of the final composite part. The angle adjustments on the machine cause the temporary response of the filaments. This study derives an analytical method to determine the real angle of the filaments on the mandrel.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
2020-10-01T00:00:00ZClassical flutter analysis of composite wind turbine blades including compressibility
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4119
Classical flutter analysis of composite wind turbine blades including compressibility
Farsadi, Touraj; Kayran, Altan
For wind turbine blades with the increased slenderness ratio, flutter instability may occur at lower wind and rotational speeds. For long blades, at the flutter condition, relative velocities at blade sections away from the hub center are usually in the subsonic compressible range. In this study, for the first time for composite wind turbine blades, a frequency domain classical flutter analysis methodology has been presented including the compressibility effect only for the outboard blade sections, which are in the compressible flow regime exceeding Mach 0.3. Flutter analyses have been performed for the baseline blade designed for the 5-MW wind turbine of NREL. Beam-blade model has been generated by making analogy with the structural model of the prewisted rotating thin-walled beam (TWB) and variational asymptotic beam section (VABS) method has been utilized for the calculation of the sectional properties of the blade. To investigate the compressibility effect on the flutter characteristics of the blade, frequency and time domain aeroelastic analyses have been conducted by utilizing unsteady aerodynamics via incompressible and compressible indicial functions. This study shows that with use of compressible indicial functions, the effect of compressibility can be taken into account effectively in the frequency domain aeroelastic stability analysis of long blades whose outboard sections are inevitably in the compressible flow regime at the onset of flutter.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
2021-01-01T00:00:00ZPassive Flow Control over an Airfoil by Control Rod at Low Reynolds Number
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4114
Passive Flow Control over an Airfoil by Control Rod at Low Reynolds Number
Durhasan, Tahir
In the present study, the flow control mechanism of SD7062 airfoil by a rod illustrated using Particle image velocimetry (PIV) technique at pre-stall angles of attack at Reynolds number of Re = 30000. The rod was installed on the suction surface of the airfoil at different chordwise locations. Diameter of the rod was normalized with the chord length of the airfoil and three diameter ratios (d / c = 0.017, 0.033 and 0.044) were examined at angles of attack of alpha = 6 degrees, 8 degrees and 10 degrees. Formation of laminar separation bubble for the baseline airfoil and the effect of rod on the laminar separation bubble were investigated in detail. It is observed that the height of boundary layer was reduced up to 22% by proper rod location and diameter ratio. Moreover, the rod suppressed the unsteady vortices over the suction surface of airfoil significantly. Therefore, the peak magnitudes of turbulent statistics were also decreased up to 30% by the rod.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
2020-11-01T00:00:00ZReference Breast Phantoms for Low-Cost Microwave Imaging
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4113
Reference Breast Phantoms for Low-Cost Microwave Imaging
Aydin, Emine Avsar; Karaoglan, Selin Yabaci
Microwave imaging provides an alternative method for breast cancer screening and the diagnosis of cerebrovascular accidents. Before a surgical operation, the performance of microwave imaging systems should be evaluated on anatomically detailed anthropomorphic phantoms. This paper puts forward the advances in the development of breast phantoms based on 3D printing structures filled with liquid solutions that mimic biological tissues in terms of complex permittivity in a wide microwave frequency band. In this paper; four different experimental scenarios were created, and measurements were performed, and although there are many vector network analyzers on the market, the miniVNA used in this study has been shown to have potential in many biomedical applications such as portable computer-based breast cancer detection studies. We especially investigated the reproducibility of a particular mixture and the ability of some mixes to mimic various breast tissues. Afterwards, the images similar to the experimentally created scenarios were obtained by implementing the inverse radon transform to the obtained data.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
2020-12-01T00:00:00Z