Detection OfSurge Precursors InLocomotive Turbocharger

Locomotive engine performance depends among operating pointoftheturbocharger depends ontheengine otherfactors onturbocharger efficiency andoperating range.exhaust flow,temperature, pressure andenginebreathing Theturbocharger operating rangecanbeconstrained athigh characteristics. Incertain operating regions ofthecompressor, pressure ratio byflowinduced instabilities, namely surge, inthe* X l f centrifugal compressor. Theresulting lossofflowresults in especially atlowflowrates coupled withhighpressure ratio or degraded engine performance, higher exhaust emissions, highduring transients, flowinduced instabilities canoccur, leading turbocharger vibration andcanleadtomechanical damageonthe tosurge. compressor andadjoining airhandling equipment. Whilesurge Fig.1depicts atypical performance mapforacentrifugal avoidance methods areavailable torestrict theoperating point to liewellwithin astatic surge-avoid-line ofthecompressor, thesecomsor, sowingpressur asau i on methods canunnecessarily restrict theoperating range, resulting flowforarangeofcompressor speeds. inloss ofoverall performance andfuel efficiency. Surgedetection andcontrol isa closed loopstrategy wherea surgeavoidance Compressor MapwthSurge Line system starts acting iftheonset ofsurge isdetected. Useofsucha Surge line strategy allows running atreduced surgemargin topermit higher S line pressure ratioacrossthecompressor, atpotentially higher*i compressor efficiency, andyields increased poweroutput fromm theengine atreduced emissions andimproved fuel efficiency. This paperdiscusses a systematic approachadoptedto detect Surge-avoid line precursors tothesurgephenomenon, basedonexperiments on 9L- full-scale turbochargers andtheuseofa real-time wavelet - algorithm todetect precursors. rotational~~~~~~~~~~~~~~ ~ enrg to drv.hopesr.Teabetari ontheslope ofthecompressor characteristic insuchawaythat compressed andleaves atahigher pressure andmassflowfor aseprsoelast oe rqec,adals te lp improved engine combustion andincreased power.The ledtohgrfeqnc(12