Author(s): Grigat Ernst
This paper gives a survey of the design and current status a noise footprint calculation program which is being developed within the framework of a medium-term initiative at Airbus Defence and Space GmbH to reduce the noise produced by high performance military aircraft. Whereas in earlier articles focus has been put on the development and validation of models for the noise sources (i.e. emission), this paper mainly comprises the aspect of modelling the sound propagation and immission. Elaborate algorithms for noise transmission are presented, besides the commonly applied geometric and atmospheric absorption/attenuation models additionally containing dedicated methods incorporating the effect of variable wind and temperature gradients. Sensitivity analyses show the qualitative and quantitative effect of the improvement of the overall calculation model by each refinement method. The effect of sound propagation on ground (i.e. immission) under special consideration of the Doppler effect can be evaluated by a set of dedicated metrics. The results of the noise footprint calculation program is displayed using a dedicated graphical user interface based on Matlab. Validation of the described algorithms and methods is performed by comparison with existing standard software for these purposes as well as with noise data generated during a dedicated flight test campaign. These activities being harmonized in the framework of a dedicatedly defined overall validation strategy and approach give way for the complete validation of the developed noise footprint calculation program.
Name: Dr Ernst Grigat