[PDF]    http://dx.doi.org/10.3952/lithjphys.49104

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 49, 91–96 (2009)


MEASUREMENT AND NUMERICAL SIMULATION OF TWO-PHASE PLASMA FLOWIN PLASMA SPRAY PROCESS
V. Grigaitienė, V. Valinčius, and R. Kėželis
Lithuanian Energy Institute, Breslaujos 3, LT-35444 Kaunas, Lithuania
E-mail: vika@mail.lei.lt

Received 26 September 2008; revised 10 February 2009; accepted 19 March 2009

Interaction of plasma jet with hard ceramic particles was numerically investigated by means of “Jets&Poudres" software improved and applied to model a specic plasma jet. The data on free plasma jet, with injected dispersed particles, its temperature and velocity distribution, as well as particles' melting state are presented. It was found that dispersed particles achieve higher temperature and velocity values than plasma gas at dimensionless distance x/d = 8–12 from exhaust nozzle. Numerical investigations were compared with experimental data. The results show that applied numerical model of two-phase high temperature jet calculation is in good agreement with experimental data and could be used to determine the optimal plasma spray parameters for coatings with desirable characteristics.
Keywords: plasma jet, plasma spraying, dispersed particles, coating synthesis
PACS: 68.47.Gh, 68.55.-a, 68.90.+g


DVIFAZIO PLAZMOS SRAUTO MATAVIMAI IR SKAITMENINIS MODELIAVIMAS PLAZMINIO PURŠKIMO PROCESE
V. Grigaitienė, V. Valinčius, R. Kėželis
Lietuvos energetikos institutas, Kaunas, Lietuva

Skaitmeniniai dvifazio plazmos srauto tyrimai buvo atlikti naudojant „Jets&Poudres“ programą, kuri yra specialiai pritaikyta modeliuoti plazmos srauto tekėjimą bei joje vykstančius procesus. Gauti dvifazio srauto modeliavimo rezultatai palyginti su eksperimentiniais duomenimis. Eksperimentinį plazminio purškimo įrenginį sudaro dispersinių dalelių maitinimo ir dozavimo sistema bei linijinis nuolatinės srovės 30–40 kW galios plazmos generatorius (PG) su karštu katodu ir laiptuotu anodu. Į aukštos temperatūros srautą tiekiamos įvairios medžiagos ar jų mišiniai: anglis, kaolinas, aliuminio, vario, cirkonio oksidai ir kt. Nustatyta, kad dispersinių dalelių temperatūra ties x/d = 8–12 viršija vidutinę dujų temperatūrą ir yra 1200–1600 K. Tiriant dalelių greičio kitimus priklausomai nuo nuskrieto atstumo, galima pastebėti, kad mažiausios dalelės per tą patį laiką pasiekia didesnį greitį. Dalelių greitis stabilizuojasi ties x/d = 8 nuo PG ištekėjimo angos ir beveik nepriklauso nuo jų dydžio. Tai rodo, kad paruoštas dengiamas substratas ties x/d = 8–12 bus bombarduojamas pastoviu jėgos impulsu, dalelių kinetinė energija bus maksimali. Gauti rezultatai parodė, kad skaitmeninio modeliavimo rezultatai neblogai sutampa su eksperimentų duomenimis, todėl gali būti naudojami nustatant optimalius plazmos purškimo parametrus, gaminant pageidaujamų savybių dangas.


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