TFaNS is a computer program that predicts the tone noise that emanates from the fan stage of a turbofan engine. With the help of this program, engineers working to reduce fan tone noise can study the effects of proposed design changes and are thus more likely to be successful in their efforts.

The interaction of the fan wake with the downstream stator vanes is a significant source of fan noise in a modern turbofan engine. Other fan-noise computer codes predict the rotor/stator tone noise and the noise radiated from the inlet and exhaust sections of fan stage separately. Unlike those codes, TFaNS predicts entire noise field, both inside and outside an engine duct. TFaNS takes account of the effects of reflection and transmission by the rotor and stator and by the duct inlet and nozzle; this is done in addition to the conventional mathematical modeling based on a concept of an annular duct and an isolated stator. In other words, TFaNS couples the results from all such computations that, heretofore, were performed separately, in order to generate a complete fan-stage noise prediction.

TFaNS includes the following modules:

  • SOURCE3D estimates the strength of the rotor/stator-interaction tone-noise source.
  • INLRAD3D and AFTRAD3D predict the propagation of the tone noise from the source, through the fan-duct termination, to the far field.
  • CUP3D couples the results from the aforementioned modules to provide a complete fan-stage noise prediction.
  • AWAKEN mediates the input, into the SOURCE3D module, of rotor-wake data that have been obtained through either measurement or else simulation by a computational fluid dynamics (CFD) code.

At present, the range of applicability of TFaNS is limited to subsonic fan-tip speeds.

This program was written by David Topol of United Technologies Corp. and Walter Eversman of the University of Missouri-Rolla for Glenn Research Center. For further information, access the Technical Support Package (TSP) free on-line at  under the Software category.

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center
Commercial Technology Office
Attn: Steve Fedor
Mail Stop 4—8
21000 Brookpark Road
Ohio 44135.

Refer to LEW-17063.