VALIDATION OF AEROACOUSTIC PREDICTIONS USING THE HELINOVI DATABASE

The European research project HeliNOVI was aimed at the enhancement of helicopter performance, safety and ride comfort. Within this project one of the principal aims was the study of the aerodynamics and aeroacoustics of the tail rotor in order to reach a deeper knowledge of the phenomenology related to it. A key activity was the design of a wind tunnel test employing the existing powered 40%-scaled BO105 helicopter model for the generation of a high-quality data base for code validation and assessment of tail rotor noise reduction means and the use of this database for the validation of simulation codes. This validation ac-tivity included code-to-code and code-to-test comparisons using the predicted and wind tunnel results. A validation activity for acoustic prediction results from six of the HeliNOVI partners has been performed. A range of partner’s methods are applied for aircraft trim, wake modelling, aerodynamic solution and aeroacoustic solution are detailed. The numerical/experimental comparisons of the results obtained by the partners show a significant variation in level of agreement with the HeliNOVI experimental data, but generally capture some of the interac-tion effects between main and tail rotors. Force noise often dominates the results and it is found that the trim methodology is crucial to the acoustic prediction. Indeed the large varia-tion in the acoustic predictions is largely due to variation in the results of the preceding aero-dynamic analyses. The HeliNOVI database of experimental and predicted dynamic, aerody-namic and aeroacoustic data provides a valuable asset for further development and validation of acoustic prediction capabilities