Detection Of Surge Precursors In Locomotive Turbocharger

Locomotive engine performance depends among other factors on turbocharger efficiency and operating range. The turbocharger operating range can be constrained at high pressure ratio by flow induced instabilities, namely surge, in the centrifugal compressor. The resulting loss of flow results in degraded engine performance, higher exhaust emissions, high turbocharger vibration and can lead to mechanical damage on the compressor and adjoining air handling equipment. While surge avoidance methods are available to restrict the operating point to lie well within a static surge-avoid-line of the compressor, these methods can unnecessarily restrict the operating range, resulting in loss of overall performance and fuel efficiency. Surge detection and control is a closed loop strategy where a surge avoidance system starts acting if the onset of surge is detected. Use of such a strategy allows running at reduced surge margin to permit higher pressure ratio across the compressor, at potentially higher compressor efficiency, and yields increased power output from the engine at reduced emissions and improved fuel efficiency. This paper discusses a systematic approach adopted to detect precursors to the surge phenomenon, based on experiments on full-scale turbochargers and the use of a real-time wavelet algorithm to detect precursors.