A new calibration method for measuring acoustic transfer matrixes with flow and application to an automotive compressor

• Improvements in automotive engine efficiency decrease carbon dioxide emissions.
• Acoustic tuning of air intake lines is used to improved engine air filling.
• Wave propagation through a radial compressor is studied to improve engine efficiency.
• A method for measuring acoustical transfer matrixes is developed.

A new method for measuring acoustic transfer matrixes with flow has been developed. It is based on two-load technique. Great improvements were obtained on specific calibration of the connections. We present here the calibration principles and validation. Measurements of basic resonating systems, first without flow then with flow up to Mach 0.2 clearly validated the accuracy of the technique, even under extreme flow conditions.This technique was developed to allow the determination of the acoustic behavior of an automotive engine intake line, comprising a compressor. Measurements of the transfer matrix of an automotive compressor are presented without flow then under realistic engine conditions. The results obtained are compared to those of a basic acoustic model of the compressor.