o:13769 Оптимизација аероакустичних феномена код узгонских површина докторска дисертација Optimization of aeroacoustic phenomena around aerodynamic surfaces : doctoral dissertation sr Бука чији је узрочник авион приликом полетања и слетања је један од главних проблема за људе који живе у околини аеродрома... Noise which is generated by the aircraft during the take off and landing is one of the main problems for the people who live in area around airport. Noise which is generated by the aircraft during the take off and landing is one of the main problems for the people who live in area around airport. One part of the noise is generated by the turbojet engine and another part is generated by the aerodynamic surfaces and other components of airframe. Development and production of good simulation tool with finite element method can help to understand complexity of the problem and to develop in the future aerodynamic parts of the aircraft which could produce lower level of noise. Acoustic sources are generated by the turbulent flow passing aerodynamic parts of the aircraft and these sources generate fluctuation of the pressure in the domain what our ear recognize as sound. If it is wanted to accurately predict location and intensity of the sound it has first to predict very accurately turbulent flow what is one challenge and than simulate propagation of pressure waves in domain. The goal of the thesis is to numerically and mathematically model vector field of velocity for the turbulent flow. From another side also the same approach will be used for pressure wave propagation. Aeroacustic simulation using finite element method overall need so many elements and time for simulation it would be also suggested the approach how to reduce the time and memory usage for simulation. In first phase it would be investigated numerical approaches to simulate turbulent flows. It is mainly used DNS-Direct Numerical Simulation, RANS-Reynolds Averaged Navier- Stokes, LES-Large Eddy Simulation. In next phase it would be developed mathematical and numerical modeling of stabilized Orthogonal Subgrid scale method with dynamical subscales. Next it would be presented short implementation in software proposed methodology and then their testing and also comparetion with existed methods. Calclation of acoustic sources or Lighthill’s tensor will be subject of next phase where transformation from time domain to frequency domain is done through Direct Fourier transformation. Mathematical and numerical modeling of pressure waves will be done with same methods as for turbulent flow. In final stage of investigation it would be done some real simulation in 2D to verify and compare of proposed methodology with existing ones. In the end it would be given the conclusion and suggestion for future work. Result obtained from the investigation will show that proposed methodology will give better and stronger representation of the acoustic sources. Different approach of turbulent modeling affecting small scales and their filtration in the solution of resolvable scale captured by the finite element mesh recovering good energy distribution in the area of small eddies and also give opportunity to model backscatter. Машинство - Ваздухопловство / Mechanical engeneering -Aerospace Datum odbrane: 13. 7. 2016. Аероакустика, бука, директна Фуријеова трансформација, нехомогена хелмхолцова једначина, Лајтхилова аналогија Aeroacoustics, Direct Fourier transformation, Inhomogeneous Helmholtzequation, Lighill’s analogy, Noise, Orthogonal Subgrid Scale Stabilization method withdynamical subscales yes 514714531 91552101 4162 91552100 514714531 2016-11-02T12:49:40.053Z 45 no 46 mentor Vladimir M. Jazarević 2016 63 mentor Boško, 1949- Rašuo 2016 63 član komisije Aleksandar, 1964- Bengin 2016 63 član komisije Aleksandar, 1959- Veg 2016 63 član komisije Marko. Miloš 2016 63 član komisije Žarko. Stevanović 2016 314 листова 42652689 http://phaidrabg.bg.ac.rs/o:13769 no yes 4 2016-11-02T12:49:40.320Z 70 11 1067197 Аероакустика, бука, директна Фуријеова трансформација, нехомогена хелмхолцова једначина, Лајтхилова аналогија Aeroacoustics, Direct Fourier transformation, Inhomogeneous Helmholtzequation, Lighill’s analogy, Noise, Orthogonal Subgrid Scale Stabilization method withdynamical subscales 629.7:534.83:519.6(043.3) 1738 11A30 2016