This paper investigates the possibility to apply Operational Modal Analysis (OMA) to vibro-acoustic response measurements during engine run-up tests. During such a runup, the engine harmonics can be considered as a multi-sine sweep excitation providing broadband acceleration and sound pressure response signals that can be used to perform modal parameter estimation. This would allow identifying a vibro-acoustic model under operational conditions. By means of extensive measurements on a laboratory set-up that possesses the features of a vibro-acoustic system such as a car, the applicability of Operational Modal Analysis to engine run-up data will be assessed. A comparison will be made with random shaker excitation. In addition, classical spectrum-based modal analysis will be compared with order-based modal analysis.
