Simulation of noise generation due to blade row interaction in a high speed compressor

The three dimensional time linearized Euler method, Lin3D, is used for tonal noise generation calculations due to cascade row interaction in a 3-stage high speed low pressure (LP) compressor. The goal is to identify the dominating sound generation mechanisms and to explore possible noise reduction potentials due to design changes. Computations are carried out for three different noise generating mechanisms, namely: Noise due to (i) viscous wakes of the upstream cascade, (ii) pressure potential field of the upstream and (iii) pressure potential field of the downstream cascades. found that the sound levels due to viscous wake interactions are considerably higher than the sound levels due to pressure potential field interference of the cascades. Furthermore, in order to identify which of the rows are relevant in terms of the noise level arriving at the inlet of IGV the sound propagation through the compressor was calculated using an in-house code based on the four-pole theory. The numbers of blades and vanes and the distance between the cascade rows of the first stage were varied as design parameters to reduce noise emissions of that LP compressor.