简介:Thispaperpresentsananalysisofthepotentialforenginespeedreductioninhydraulicequipment,takingintoaccountnotonlytheminimumenginespeedrequiredtomeetthecurrentflowdemand,butalsotheminimumspeedcapableofacceleratingtheenginetomeetincreasedflowdemandinthenearfuture.Thisisapredictivetask,asitrequiresanestimateoftheoperator'sintentiontoincreaseflowdemand.Wepresentananalysisofthepotentialforenginespeedreductionusingaworkcyclefroma40tonexcavatorloadingatruck,whichresultsinapotential33%reductioninthemeanenginespeedwithnoreductioninusefulworkrate.Wealsopresenttwonewenginespeedcontrolalgorithmstoperformthispredictivetask.
简介:Laboratoryexperimentswereconductedtostudythespallationbehaviourofthermalbarriercoatings(TBCs)onaero-engineturbinebladesmanufacturedbytheelectron-beamphysicalvapourdepositiontechnique(EB-PVD).Intactbladeswereheatedattemperature1135°Cinafurnaceforcertaintimeandthencooledtotheroomtemperatureinthelaboratorycondition.Itwasfoundthatnospallationoccurredduringcooling,butspallationhappenedatconstantroomtemperatureaftercooling.Thespallationmechanismisstudiedbyusingthemechanicalmodeldeveloped(Harvey2017andWang2017),whicharebasedonthehypothesisofpocketsofenergyconcentration(PECs).Someobservationsofthespallationbehaviourarewellpredictedbythemodel.
简介:Whenanaircraftishoveringordoingadive-hikeflightatafixedspeed,aconstantadditionalinertialforcewillbeinducedtotherotorsystemoftheaero-engine,whichcanbecalledaconstantmaneuverload.Takehoveringasanexample.AJeffcottrotorsystemwithabiasedrotorandseveralnonlinearelasticsupportsismodeled,andthevibrationcharacteristicsoftherotorsystemunderaconstantmaneuverloadareanalyticallystudied.Byusingthemultiple-scalemethod,thedifferentialequationsofthesystemaresolved,andthebifurcationequationsareobtained.Then,thebifurcationsofthesystemareanalyzedbyusingthesingularitytheoryforthetwovariables.IntheEG-plane,whereEreferstotheeccentricityoftherotorandGrepresentstheconstantmaneuverload,twohysteresispointsetsandonedoublelimitpointsetareobtained.Thebifurcationdiagramsarealsoplotted.Itisindicatedthattheresonanceregionsofthetwovariableswillshifttotherightwhentheaircraftismaneuvering.Furthermore,themovementalongthehorizontaldirectionisfasterthanthatalongtheverticaldirection.Thus,thedifferentoverlappingmodesofthetworesonanceregionswillbringaboutdifferentbifurcationmodesduetothenonlinearcouplingeffects.Thisresultlaysatheoreticalfoundationforcontrollingthestabilityoftheaero-engine’srotorsystemunderamaneuverload.