Aero-vibro Acoustic Simulation of an Ultrahigh-Speed Elevator
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Suurnopeushissin akustinen simulointi
There are many solutions for computing sound and each one of them have advantages and limitations. The challenge when using deterministic methods for acoustic simulation in case of complex application, derives from the need of accurate vibrational response of the model. Validating each mode of a complex structure, when the frequency range of interest covers hundreds of natural frequencies is expensive. In addition, in order to have accurate response, the model cannot be oversimplified and due to its size, the computation is long. The advantage of using statistical methods derives from lower requirements for validating each eigenfrequency, because average energies are considered. In addition the dimensional and material tolerances have lower impact on final results. However the method is less accurate for a specific solution with a clear tonal resonance. In this study a hybrid method has been chosen: for lower frequencies where the tonal resonances are significant a finite element method was applied; for higher frequencies a statistic energy method has been chosen. The combination between the two methods has been performed in the multiphysics environment software VA One. There are several sources of sound inside an elevator shaft, which have to be evaluated in order to assess their impact on the sound inside the car. For this reason test data have been used for determining some of the vibrational contribution, computational fluid dynamics for computing the “wind” contribution and boundary element method for computing the acoustic reverberant contribution of the shaft.