简介:Differentfrombirdsandinsects,batshavecomplexwing-deformationcapacitytogeneratehighaerodynamicforces.Inflight,theactivelymorphingofbatwingincludesthetwistingfromwingroottowingtip,thecamberingalongthechordwisedirection,thebendingalongthespanwisedirectionandthewingarea-changingcausedbythestretchandretractionofthewingspan.Itwasfoundthatthehighthrustandliftrequiredinbatflightaredependentonthewingtwistingandcamberingrespectively.Moreover,theintegratedwing-morphinggeneratestheaerodynamicliftandthrustmainlyduringthedownstrokeandalmostnegligibleforcesduringtheupstroke.Thewingarea-changingandbendingcanbeusedtoamplifythepositiveforcesinthedownstrokedurationandreducethenegativeforcesintheupstrokeduration.
简介:Thisletterdescribesnumericalsimulationoftheunsteadyflowoveraslow-flyingbatbyusingtheimmersedboundarymethodbasedonthemeasuredbatwinggeometryandkinematics.Themainvorticalstructuresaroundthebatflappingwingsareidentified,illuminatingthelift-generatingroleoftheleadingedgevorticesgeneratedmainlyinthedownstroke.Furthermore,theliftdecompositionindicatesthatthevortexlifthasthedominantcontributiontothetime-averagedliftandtheliftassociatedwiththefluidaccelerationhastherelativelymoderateeffect.
简介:Largeactivewingdeformationisasignificantwaytogeneratehighaerodynamicforcesrequiredinbat’sflappingflight.Besidesthetwisting,elementarymorphingmodelsofabatwingareproposed,includingwing-bendinginthespanwisedirection,wing-camberinginthechordwisedirection,andwingarea-changing.Aplateofaspectratio3isusedtomodelabatwing,andathree-dimensionalunsteadypanelmethodisusedtopredicttheaerodynamicforces.Itisfoundthatthecamberingmodelhasgreatpositiveinfluenceonthelift,followedbythearea-changingmodelandthenthebendingmodel.Furtherstudyindicatesthatthevortexcontrolisamainmechanismtoproducehighaerodynamicforces.Themechanismsofaerodynamicforceenhancementareasymmetryofthecamberedwingandamplificationeffectsofwingarea-changingandwingbending.Liftandthrustaregeneratedmainlyduringdownstroke,andtheyarealmostnegligibleduringupstrokebytheintegratedmorphingmodel-wing.