CFD and experimental procedures (within two test-rigs which were built-up during the dissertation) were used to investigate the behaviour of a GT air intake system and silencer. The objective was firstly to reduce the pressure loss of the system by means of channel optimisation and compressor inflow redirection. Secondly to examine the silencers in terms of pressure loss and vibration behaviour. Hereby special focus is drawn to the influence of the porous medium on the latter properties. At first of all a numerical model 3D stationary air intake system and of a stationary 2D silencer were created, solved and analysed. Following an unsteady model with a moving mesh was set-up to obtain information of the flow field under simplified simulated vibration. Thirdly a selection of porous foams was studied. The investigations have been undertaken mainly on a numerical basis. Experiments on the other hand were necessary to determine coefficients of the foams for the numerical calculations as input for the solver. The calculations have been done on a porous system to determine loss coefficients and the ability to equalise pressure gradients. The intake pressure loss was reduced by approx. 30%, furthermore some good results were found concerning the package specific pressure loss of a porous medium as well as its cross-flow capability. Out of this, conclusions were drawn of the ability to reduce vibrations in the silencer derived from wake formation and interaction of the two silencer rows and silencers can be optimized in combination with its sound absorbing capability.