Measurements of flow-induced excitation of lightweight vehicle structures

Abstract

The use of lightweight construction in vehicle manufacturing is an interesting possibility for reducing fuel consumption. At present lightweight constructions are being used to lower the weight not only of new aircraft but also of new terrestrial vehicles. However, these construction methods using new materials place new demands on the level of vehicle acoustics to ensure that passenger comfort is maintained and/or improved. The acoustic and hydrodynamic pressure fluctuations arising from excitation of the fuselage during cruise flight, of the side window in cars and of the body of high-speed trains is one of the major sources of noise. The German Aerospace Center conducted three flight tests on a single aisle medium-range aircraft to measure the noise excitation, transmission and radiation into the cabin. These measurements are used to quantify the excitation and to validate numerical simulations. A pressure sensor array was used to measure the turbulent boundary layer. With this array it was possible to separate the hydrodynamic from the acoustic pressure fluctuations. The results are used to describe the aeroacoustic sources in a more precise manner than that given by the two current, state of the art models (Corcos, Efimtsov). These same methods were used to measure the hydrodynamic and acoustic pressure fluctuations at the side window of a generic car model.