Calculation of the drop in sound pressure level and frequency analysis of aerospace engine test cell

Aerospace engines testing is a source of noise pollution and determining the low frequency acoustic characteristics of the test cell, plays an important role in optimally control of the sound field and reducing the level of sound pressure and pollution. In this study, the drop in average sound pressure level is numerically predicted by constructing a test cell according to ISO 140 standard. To solve the sound propagation equations, modeling the contact between the structure and the fluid, dynamic coupling of the structure and the fluid is performed and to calculate the acoustic energy distribution in the fluid and the structure, Abaqus finite element software is used. Cells with different dimensions and insulation and simply support conditions are modeled and the average sound pressure level drop of each model is calculated and compared. The optimal dimensions of the cell are determined, then the independence of the mesh is checked and the results are verified using experimental data. The measured sound pressure drop values are reported for the quarter band. To ensure that it is not resonated by acoustic force, the frequency analysis of the structure was performed and it was determined that the designed test cell eliminates noise pollution. Cell size optimization shows that the best test cell radius for the 90 to 150 Hz frequency range is 2.25 m.