Turbomachinery Aeroacoustic Calculations using a Time Domain Chorochronic Method

Licentiate thesis, 2008

Noise regulations for aircrafts that fly over populated areas are continuously becoming stricter. This in combination with increasing computational capabilities has boosted interest in aeroacoustic computations in the aerospace industry. New numerical methods that are able to predict the noise will play a mayor role in future aircraft and engine designs, and validation and possibly improvements of these new methods are needed for convincing results. This thesis shows how accurate and efficient nonlinear bladerow interaction computations with a focus on aeroacoustics can be made. The chorochronic periodicity that occurs when the number of blades in each bladerow are not the same is explored and utilized to make the computation more efficient. The acoustic response from a stator vane with rotor wake impingement is calculated with the chorochronic method and compared to an existing linear method, and the results are in good agreement. Preliminary results of a simulation of a counter-rotating propeller are also presented.