A New Method of Powertrain Noise Source Identification using a Particle Velocity Probe for Acoustic Intensity Measurement

This paper describes the use of a new probe for direct measurement of particle velocity for an acoustic intensity survey of a test engine at Ricardo UK.

The new probe includes both a pressure and a particle velocity transducer in a single package [2], utilising the miniature hot wire principle. This probe enables near-field direct measurement of the acoustic intensity on a test powertrain, and is referred to here as the ‘P-U’ (Pressure- Velocity) Probe.

The new technique has significant advantages over the traditional pressure differential acoustic intensity technique that include a wider frequency bandwidth, better rejection of the reverberant sound field and the ability to easily and safely take measurements over a wider range of engine operating conditions.

The use of the method for noise source identification is described and the test results are shown to compare well with those obtained from the traditional pressure differential acoustic intensity technique.