分析简介robert l roedts ii气动.pptx

ABriefIntroductiontoHelicoptersRobertL.RoedtsIIThePennsylvaniaStateUniversityRotorcraftCenterofExcellence

WhatisaHelicopter?UniqueFeaturesRotating-wingvehiclesAbilitytohoverLandandtake-offverticallyFlyforward,backwardandsidewaysHelicoptersarecloselyrelatedtoautogyrosandtiltrotors.

MotivationTheoveralluniqueaspectofahelicopterisit’sabilitytohoverforextendedperiodsoftime.Theabilitytohoveritaveryusefulattribute.Angoodexampleisthatofahummingbird.

Withthisabilitytohover,helicopterscanperformawiderangeofmissions.HelicoptersatWork

ComparisonofFixed-WingAircraftandHelicoptersFixedWingAircraft

ComparisonofFixed-WingAircraftandHelicoptersHelicopter

ConfigurationsofRotorcraftManydifferentwaystocounterReactiveTorqueOtherpossibilities:Tipjets,tipmountedenginesQuestion:Whydoeachofthesemethodswork?Whatarethelikelyadvantagesanddisadvantagesofeach?

ConfigurationsofRotorcraft

MainRotor-TailRotorConfig.

ConfigurationsofRotorcraft

TandemRotors(Chinook)

ConfigurationsofRotorcraft

CoaxialRotors(KamovKA-52)

ConfigurationsofRotorcraft

NOTARHelicopter

ConfigurationsofRotorcraft

TiltRotor(BA609)

UnequalLiftDistributionLift~V2

High-SpeedForwardFlightLimitationsAstheforwardspeedincreases,advancingsideexperiencesshockeffects,retreatingsidestalls.Thislimitsthrustavailable.Vibrationsgoup,becauseoftheincreaseddynamicpressure,andincreasedharmoniccontent.Shocknoisegoesup.Fuselagedragincreases,andparasitepowerconsumptiongoesupasV3.Weneedtounderstandandaccuratelypredicttheairloadsinhighspeedforwardflight.

InteractionalAerodynamicsTherearemanywaystodealwiththeseproblems.Oneexamplewouldbetheairfoilselection.

RotorDescentStates

GroundInteractionsAtlowforwardspeeds,lesspowerisrequired.

AirfoilDesignRotorcraftpresentaninterestingproblemforairfoildesign.