Improvements have been made in the finite element model of the acoustic radiated field from a turbofan engine inlet in the presence of a mean flow. The problem of acoustic radiation from a turbofan engine inlet is difficult to model numerically because of the large domain and high frequencies involved. A numerical model with conventional finite elements in the near field and wave envelope elements in the far field has been constructed. By employing an irrotational mean flow assumption, both the mean flow and the acoustic perturbation problem have been posed in an axisymmetric formulation in terms of the velocity potential, thereby minimizing computer storage and time requirements. The finite element mesh has been altered in search of an improved solution. The mean flow problem has been reformulated with new boundary conditions to make it theoretically rigorous. The sound source at the fan face has been modeled as a combination of positive and negative propagating duct eigenfunctions. Therefore, a finite element duct eigenvalue problem has been solved on the fan face and the resulting modal matrix has been used to implement a source boundary condition on the fan face in the acoustic radiation problem. In the post processing of the solution, the acoustic pressure has been evaluated at Gauss points inside the elements and the nodal pressure values have been interpolated from them. This has significantly improved the results. The effect of the geometric position of the transition circle between conventional finite elements and wave envelope elements has been studied and it has been found that the transition can be made nearer to the inlet than previously assumed.
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January 1995
Research Papers
Improved Finite Element Modeling of the Turbofan Engine Inlet Radiation Problem
I. Danda Roy,
I. Danda Roy
Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri-Rolla, Rolla, MO 65401
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W. Eversman
W. Eversman
Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri-Rolla, Rolla, MO 65401
Search for other works by this author on:
I. Danda Roy
Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri-Rolla, Rolla, MO 65401
W. Eversman
Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri-Rolla, Rolla, MO 65401
J. Vib. Acoust. Jan 1995, 117(1): 109-115 (7 pages)
Published Online: January 1, 1995
Article history
Received:
December 1, 1993
Online:
February 26, 2008
Citation
Danda Roy, I., and Eversman, W. (January 1, 1995). "Improved Finite Element Modeling of the Turbofan Engine Inlet Radiation Problem." ASME. J. Vib. Acoust. January 1995; 117(1): 109–115. https://doi.org/10.1115/1.2873853
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