Assessment of a frequency-domain linearised Euler solver for turbofan aft radiation predictions and comparison with measurements

This paper presents a frequency-domain computational aeroacoustics tool for predicting aft noise radiation through turbofan ducts and jets and its application to two realistic engine exhaust configurations which have been experimentally tested. The tool is based on the discretised axisymmetric form of the linearised Euler equations in conjunction with perfectly matched layer equations at the inlet and far-field boundaries using high-order finite differences. The resultant linear system of equations is inverted by the state-of-the-art parallel sparse solver MUMPS. The far-field prediction is carried out by integrating Kirchhoff's formula in frequency domain. The code has already been verified extensively for idealized semi-infinite duct cases with comparisons to available analytical solutions with very good agreement. Therefore, we concentrate in this paper on numerical solutions to the experimental cases tested in the EC FP6 Project TURNEX (TUrbomachinery noise Radiated through the engine EXhaust) to assess and partially validate the present solver further. Comparisons of the computed results with the measured data reveal that the solver predicts the general noise radiation patterns and sound levels reasonably well, so long as the target in-duct azimuthal mode remains dominant as it radiates to the far-field. The agreement strongly suggests that, at least for the range of mean flows and acoustic conditions considered, the physical aeroacoustic radiation processes are fully captured through the frequency-domain solutions to the linearised Euler equations.


A computational procedure for estimating residual stresses and secondary plastic flow limits in nonlinearly strain hardening rotating shafts
Eraslan, Ahmet Nedim (Springer Science and Business Media LLC, 2005-03-01)
A computational procedure to estimate the residual stress distributions and the limit angular speeds for avoiding secondary plastic deformation in nonlinearly strain hardening rotating elastic-plastic shafts is given. The model is based on von Mises yield condition, J(2) deformation theory and a Swift-type hardening law. The boundary value problem for the governing nonlinear differential equation is solved by a shooting method using Newton iterations with numerically approximated tangent. Solid as well as h...
ONDER, M; Kuzuoğlu, Mustafa (Institution of Engineering and Technology (IET), 1992-10-01)
An optimisation approach is presented for the problem of reconstructing the permittivity and conductivity profiles of a dielectric slab from the reflected and transmitted field data. The problem is treated as an optimal control problem where the norm of the difference of measured and calculated boundary data is minimised subject to the state equation governing the system. The original constrained optimisation problem is reduced to the evaluation of stationary points of an augmented functional which is obtai...
An experimental study of residual fiber strains in Ti-15-3 continuous fiber composites
Pickard, S.M.; Miracle, D.B.; Majumdar, B.S.; Kendig, K.L.; Rothenflue, L.; Çöker, Demirkan (Elsevier BV, 1995-01-01)
A simplified experimental technique to determine the axial fiber residual strain in continuously-reinforced metal matrix composites is described. The residual fiber strains in two Ti-15V-3Cr-3Al-3Sn/SiC metal matrix composites have been measured with this technique. Residual fiber strains on the order of 0.2% are measured in the as-processed condition, and the residual stresses approach zero after testing the composite in tension to failure at room temperature. A conceptual description of the effect of tens...
Aerodynamic shape optimization of wind turbine blades using a parallel genetic algorithm
Polat, Ozge; Tuncer, İsmail Hakkı (2013-12-31)
An aerodynamic shape optimization methodology based on Genetic Algorithm and Blade Element Momentum theory is developed for rotor blades of horizontal axis wind turbines Optimization studies are performed for the maximization of power production at a specific wind speed, rotor speed and rotor diameter. The potential flow solver with a boundary layer model, XFOIL, provides sectional aerodynamic loads. The sectional chord length, the sectional twist and the blade profiles at root, mid and tip regions of the b...
LI, W; KAKAC, S; HATAY, FF; OSKAY, R (Springer Science and Business Media LLC, 1993-01-01)
An experimental apparatus was designed, built and used to study the behavior of transient forced convection in a rectangular duct with and without barriers due to a sinusoidal heat input at the inlet. to simulate the electric heating and cooling inside the computer. A wide range of Reynolds number (400 less-than-or-equal-to Re less-than-or-equal-to 20,000) and inlet frequencies (0.01 Hz less-than-or-equal-to beta less-than-or-equal-to 0.08 Hz) was covered in this experimental study for both laminar and turb...
Citation Formats
Y. Özyörük, “Assessment of a frequency-domain linearised Euler solver for turbofan aft radiation predictions and comparison with measurements,” 2010, vol. 6, Accessed: 00, 2020. [Online]. Available: