Numerical simulation of fore and aft sound fields of a turbofan

A framework for predicting fan related noise from high bypass ratio engines is presented. The methodology accounts for both fore and aft radiation and includes the effects of liner treatment on the engine walls. Solutions are obtained through a combination of Euler and linearized Euler solvers, coupled with a Kirchhoff formulation for far-field noise prediction. The nacelle region is solved using the Eider solver, whereas the linearized Euler solver is used for the fan exhaust stage. Switching to the linearized Euler solver in the aft region has been necessary to overcome difficulties experienced due to the coupling of the acoustic modes with flow near the engine exhaust boundary and appearance of flow instabilities in the shear layer trailing the exhaust shroud. Results are presented for spinning modes from a turbofan engine with acoustic treatment.


Computational study of flapping airfoil aerodynamics
Tuncer, İsmail Hakkı (American Institute of Aeronautics and Astronautics (AIAA), 2000-05-01)
Unsteady, viscous, low-speed flows over a NACA 0012 airfoil oscillated in plunge and/or pitch at various reduced frequency, amplitude, and phase shift are computed. Vortical wake formations, boundary-layer flows at the leading edge, the formation of leading-edge vortices and their downstream convection are presented in terms of unsteady particle traces. Flow separation characteristics and thrust-producing wake profiles are identified. Computed results compare well with water tunnel flow visualization and fo...
Flight simulation and control of a helicopter
Erçin, Gülsüm Hilal; Tekinalp, Ozan; Department of Aerospace Engineering (2008)
In this thesis the development of a nonlinear simulation model of a utility helicopter and the design of its automatic flight control system is addressed. In the first part of this thesis, the nonlinear dynamic model for a full size helicopter is developed using the MATLAB/SIMULINK environment. The main rotor (composed of inflow and flapping dynamics parts), tail rotor, fuselage, vertical stabilizer, horizontal stabilizer of the helicopter are modeled in order to obtain the total forces and moments needed f...
Nonsinusoidal path optimization of a flapping airfoil
Kaya, Mustafa; Tuncer, İsmail Hakkı (American Institute of Aeronautics and Astronautics (AIAA), 2007-08-01)
The path of a flapping airfoil undergoing a combined, nonsinusoidal pitching and plunging motion is optimized for maximum thrust and/or propulsive efficiency. The nonsinusoidal, periodic flapping motion is described using nonuniform rational B splines. A gradient based algorithm is then employed for the optimization of the nonuniform rational B-spline parameters. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver in a parallel computing environment. The numerical evaluation of the g...
Nonlinear flutter calculations using finite elements in a direct Eulerian-Lagrangian formulation
Seber, Guclu; Bendiksen, Oddvar O. (American Institute of Aeronautics and Astronautics (AIAA), 2008-06-01)
A fully nonlinear aeroelastic formulation of the direct Eulerian-Lagrangian computational scheme is presented in which both structural and aerodynamic nonlinearities are treated without approximations. The method is direct in the sense that the calculations are done at the finite element level, both in the fluid and structural domains, and the fluid-structure system is time-marched as a single dynamic system using a multistage Runge-Kutta scheme. The exact nonlinear boundary condition at the fluid-structure...
Optimization of Flapping Motion Parameters for Two Airfoils in a Biplane Configuration
Kaya, Mustafa; Tuncer, İsmail Hakkı; Jones, Kevin D.; Platzer, Max F. (American Institute of Aeronautics and Astronautics (AIAA), 2009-03-01)
Flapping motion parameters of airfoils in a biplane configuration are optimized for maximum thrust and/or propulsive efficiency. Unsteady, viscous flowfields over airfoils flapping in a combined plunge and pitch are computed with a parallel flow solver on moving and deforming overset grids. The amplitudes of the sinusoidal pitch and plunge motions and the phase shift between them are optimized for a range of flapping frequencies. A gradient-based optimization algorithm is implemented in a parallel computing...
Citation Formats
Y. Özyörük, “Numerical simulation of fore and aft sound fields of a turbofan,” AIAA JOURNAL, pp. 2028–2034, 2004, Accessed: 00, 2020. [Online]. Available: