Influence of reverberation room forms on the modal density of the acoustic test rig

One of the main parts of the acoustic test rig is a reverberation room, where whole acoustic power is focused inside this room. The correct form of scientifically sound reverberation room and its volume can significantly optimize the cardinality and financial parameters of the test rig. The fundamental of the best installation is the density of the spectrum of natural frequencies (the density of modes) reverberation room. When you create a diagnostic rig, the dynamic properties of the spacecraft design can be taken into account. For example, to excite vibrations of the spacecraft on its own forms, it is necessary that in the spectrum of the reverberation chamber there are resonance frequencies of the object of the study. If the resonance frequency on the AC scale is too often or is not defined, the ideal camera for research spacecraft should have a continuous spectrum of natural frequencies. Although in practice the establishment of such cameras is not possible, the choice of the shape and size of the reverberation room has a significant impact on the density of natural frequencies, in other words, the proximity to the diffuse sound field. The problem of finding natural frequencies of acoustic oscillations reverberation rooms of different shapes is considered. The formulas for calculating natural frequencies room shaped parallelepiped, cylinder, hollow cylinder are given. Numerical simulation of the natural frequencies of the spectrum, with different ratios of linear sizes of rooms has been conducted. The results of the comparative analysis of the density of modes are given. The results of numerical studies have shown sufficient, for acoustic vibration tests, the density of the natural frequencies of the cylindrical room. The conclusion about the possibility of using plants to create a cylindrical shape of acoustic test facilities has been given.