For modal analysis, the geometry being measured is divided into discrete cylinder and taper elements which enable the actual cross section characteristics to be modelled precisely. This discrete model incorporates extensive experimental know-how because the sub-division of this calculation field has a decisive impact on the quality of the calculation result. Geometry broken down into discrete elements, combined with other calculation parameters such as temperature, flow speed and acoustic conditions, represent the data on which special program code can be based. Any acoustic parameters, including frequency-dependent ones, are permitted here. In the event of complex geometries proving impossible to describe by means of theoretical approaches to the parameter in question, we can also offer an experimental examination of parameters based on the n ?microphone method.

The program used was developed in-house by IfTA GmbH and is being extended continuously. Individual adaptations to the specific requirements of customers can be made at any time. This allows, among other things, for the length or cross section of individual tube elements to be varied without any problem in order to examine specific frequency and mode displacements.