Acoustic One-Dimensional Compressor Model for Integration in a Gas-Dynamic Code 2012-01-0834

An acoustic one-dimensional compressor model has been developed. This model is based on compressor map information and it is able to predict how the pressure waves are transmitted and reflected by the compressor. This is later on necessary to predict radiated noise at the intake orifice. The fluid-dynamic behavior of the compressor has been reproduced by simplifying the real geometry in zero-dimensional and one-dimensional elements with acoustic purposes. These elements are responsible for attenuating or reflecting the pressure pulses generated by the engine. In order to compensate the effect of these elements in the mean flow variables, the model uses a corrected compressor map. Despite of the fact that the compressor model was developed originally as a part of the OpenWAM™ software, it can be exported to other commercial wave action models. An example is provided of exporting the described model to GT-Power™.

The model has been validated using experimental results obtained in a turbocharger test bench under pulsating flow conditions. The characteristics of the pressure waves (amplitude, frequency and mean flow) are similar to those of the pulses that the compressor undergoes when working coupled to a reciprocating internal combustion engine. This facility allows wave decomposition upstream and downstream of the compressor. The experimental pressure waves have been compared versus the results provided by the model analyzing both in frequency domain and in time domain in the two codes used to host the model. Finally, a comparison between the proposed 1D-0D model, which furthermore applies the compressor map, and the standard methodology used by GT-Power™, which directly only interpolates in the compressor map, has been performed. Results show better performance in the case of the proposed model and evidence the interest for the compressor geometrical description.