Source Scanning Technique for Simulating TBL-Induced Vibrations Measurements

Abstract

Measuring the vibro-acoustic response of structures subjected to a turbulent boundary layer (TBL) excitation in operating conditions remains an open issue for experimenters. Generally, in situ measurements, e.g. flight tests, underwater measurements and wind tunnel measurements are carried out, although they require expensive facilities. As an alternative to in situ measurements, experimental simulations in a laboratory environment have been developed. The main issue of these substitute experiments is the synthesis of an excitation field equivalent to TBL wallpressure fluctuations with the help of standard transducers (shakers, loudspeakers, etc.). In the present paper, we propose an alternate off-line methodology to deal with the experimental simulation of vibrations induced by a spatially correlated random pressure field, such as TBL excitation. The proposed methodology is called Source Scanning Technique (SST) and relies on two main features: a wall-pressure plane wave expansion of the target random wall-pressure field and two identification steps based on the concept of synthetic array to simulate TBL-induced vibrations from a set of transfer functions. In the present paper, the theoretical description of the SST and its experimental implementation are detailed.