Noise generation from turbomachinery has received increased research attention during the last several decades. This was prompted initially by the advance of modern high speed jet aircraft and is now promoted by increasingly strict environmental noise level restrictions and customer demands. In order to limit development costs and time design and analysis of candidate geometries are performed on computers and this requires reliable prediction tools.
A good part of the research so far has focused on noise generation mechanisms in axial machines with the aim of reducing noise emission from aircraft engines. However, radial machines have not received the same level of attention. It seems that the main reason for this discrepancy is the great difficulties in predicting and analysing the very complex flow structures. This view is supported by the total lack of published numerical investigations and the truly challenging task of obtaining experimental flow field data at sufficient locations and in adequate detail to characterise the flow field.
This research is concerned with predicting and characterising noise sources in turbochargers. The aim is to develop numerical techniques for identifying noise generation mechanisms with the ultimate purpose of predicting noise signatures for changing geometries and operating points. The developed methods are currently being validated against the experimentally obtained noise data for a simplistic geometry. Once this step is successfully completed a whole turbine stage will be modelled to ascertain whether trends can be correctly predicted. Along the way such issues as non-reflecting boundary conditions, numerical and experimental methods, parallel computation and others will have to be considered.