Wankel rotary engines

Wankel rotary engines

1. EME-505 I.C.ENGINES AND COMPRESSORS
UNIT-1
Wankel Rotary Engines
(2013 BATCH)
V.K.Yadav
Mechanical Engineering Department
GLBITM
May 20, 2021

2. Can you relate what you have
seen in video ???
May 20, 2021

3. ROTARY ENGINES
Wankel Engine (1957)
invented by Felix Wankel
Rotary engines use the four-stroke combustion
cycle, which is the same cycle that four-stroke
piston engines use. But in a rotary engine, this is
accomplished in a completely different way.

4. Theheartofarotaryengineistherotor.Thisisroughlythe
equivalentofthepistonsinapistonengine.Therotoris
mountedonalargecircularlobeontheoutputshaft.This
lobeisoffsetfromthecenterlineoftheshaftandactslikethe
crankhandleonawinch,givingtherotortheleverageit
needstoturntheoutputshaft.Astherotororbitsinsidethe
housing,itpushesthelobearoundintightcircles,turning
threetimesforeveryonerevolutionoftherotor.
j

5. Wankel Engines
intake
exhaust
+ve
Novalvesneeded
Continuousmotion
lessvibration
-ve
Leaksthroughseals
lowcompression
ratio
pollution(highlevelsof
HCandCO)
May 20, 2021

6. Why A Rotary Engine?
•Therotaryenginehasalotsofadvantagesthatmakeita
formidablecontenderforsomeofthetaskscurrentlyperformed
byreciprocatingengines.
•Thepistoninafour-stroke-cyclereciprocatingenginemust
momentarilycometorestfourtimespercycleasitsdirection
ofmotionchanges.
•Incontrast,themovingpartsinarotaryenginearein
continuousunidirectionalmotion.
•Higheroperatingspeeds,easeofbalancing,andabsenceof
vibrationareafewofthebenefits.
•Thehighoperatingspeedsallowtheenginetoproducetwice
asmuchpowerasareciprocatingengineofthesameweight.
•Ithassignificantlyfewerpartsandoccupieslessvolumethana
reciprocatingengineofcomparablepower.
May 20, 2021

7. Construction of The Wankel Engine
•Figureshowsacross-section
ofarotaryengine.
•The stationary housing
enclosesamovingtriangular
rotorthatrotateswithits
apexesinconstantcontact
withthehousinginnersurface.
•Airandcombustiongasesare
transportedinthespaces
betweentherotorandthe
housing.
•Therotorridesonaneccentric
thatisanintegralpartofa
shaft,asshowninthedual
rotorcrankshaft.
May 20, 2021

8. Parts of A Wankel Engine
•The housing and rotor of a rotary engine designed for aircraft
application are shown in Figure below.
May 20, 2021

9. Wankel Engine Operation: Intake
•TheoperationoftheWankelengine
asanOtto-cycleenginemaybe
understoodbystudyingtheevents
associated with the
counterclockwisemovementofagas
volume isolatedbetween the
housingandoneoftherotorflanks.
•Theair-fuelmixturemaybesupplied,
byaconventionalcarburetor,
throughtheintakeportlabeledIin
Figure.
•Astheshaftandrotorturn,the
intakeportiscovered,trappinga
fixedmassofairandfuel(assuming
noleakage).
•Thisisanalogoustothegasmass
capturedwithinthecylinder-piston
volumebyclosureofareciprocating
engineintakevalve.

10. Wankel Engine Operation: Compression
•Astherotorcontinuestoturn,the
captured(crosshatched)volume
containedbetweentherotorand
housingdecreases,compressing
theair-fuelmixture.
•When itreachestheminor
diameter,theactivemixture
volume is a minimum
correspondingtothevolumeat
topdead centerinthe
reciprocatingengine.
May 20, 2021

11. Wankel Engine Operation: Ignition & Power
•Oneormoresparkplugs,as
indicatedatthetopofeach
housing,initiatecombustion,
causingrapidrisesinpressure
andtemperature.
•The hot, high-pressure
combustiongastransmitsa
forceF[part(d)]totheeccentric
throughtherotor.
•Notethat,duringthepower
phase,thelineofactionofthe
force F provides a
counterclockwisetorqueacting
abouttheshaftaxis.
May 20, 2021

12. Wankel Engine Operation: Exhaust
•Astherotationproceeds,the
expandinggasesdrivetherotor
untiltheexhaustportisexposed,
releasingthem[part(e)].
•Theexhaustprocesscontinuesas
theintakeportopenstobegina
newcycle.
•Thisportoverlapisapparentin
thelowervolumeshowninpart
(b).
•Insummary,eachflankofthe
rotorisseentoundergothesame
intake,compression,ignition,
power,andexhaustprocessesas
in a four-stroke-cycle
reciprocatingOttoengine.
May 20, 2021

13. Remarks on Wankel Operation
•Allthreeflanksoftherotor
executethesameprocesses
atequallyspacedintervals
duringonerotorrotation.
•Hencethreepowerpulses
aredeliveredperrotationof
therotor.
•Becausetherearethreeshaft
rotationsperrotorrotation,
theWankelenginehasone
powerpulsepershaft
rotation.
•Thusithastwiceasmany
powerpulsesasasingle-
cylinderfour-stroke-cycle
reciprocating engine
operatingatthesamespeed,
aclearadvantage in
smoothnessofoperation.
•Thisfeatureofonepower
pulsepershaftrotation
causesmanypeopleto
comparetheWankelengine
withthetwo-stroke-cycle
reciprocatingengine.
May 20, 2021

14. Closure
•Continuedengineeringresearchontherotaryenginehas
resultedinperformanceimprovementsthroughimproved
seals,lean-burncombustion,fuelinjection,integralelectronic
control,improvedintakedesign,weightreduction,and
turbocharging.
•Despitevehicleweightincreases,theMazdaRX-7withatwo-
rotor80-in.
3
displacementengineimproved9.4%infuel
consumptionand8%inpoweroutputbetween1984and1987.
•Duringthistimeperiod,theadditiontotheengineofa
turbochargerwithintercoolingincreaseditspoweroutputby
35%.
•TheMazdaRX-Evolv,ayear-2000conceptcar,hasanaturally-
aspiratedrotaryenginecalled.RENESIS.
•Thetwo-rotor,sideintakeandexhaustengineisreportedto
havereducedemissionsandimprovedfueleconomyandto
haveattained280horsepowerat9000rpmand226N-mtorque
at8000rpm.

15. Rotary Combustion Engines:

16. Rotor Visual & Explanation

17. Anatomy Continued …

18. Rotary Combustion Engines:
–Intake:
–Compression
:
–Power:
–Exhaust:

19. Intake:
A
B

20. Compression:
A
B

21. Power:
A
B

22. Exhaust:
A
B

24. Rotary Combustion Engines: