Numerical simulation of temperature and velocity fields in plasma spray

Abstract

Based on the turbulence jet model, with respect to Ar-He mixture plasma gas injecting to ambient atmosphere, the temperature filed and velocity field under typical working conditions were investigated. Given the conditions of I=900 A, F_Ar = 1.98 m³/h, F_He = 0.85 m³/h, it is found that both the temperature and the velocity undergo a plateau region near the nozzle exit (0–10 mm) at the very first stage, then decrease abruptly from initial 13 543 K and 778.2 m/s to 4 000 K and 260.0 m/s, and finally decrease slowly again. Meanwhile, the radial temperature and radial velocity change relatively slow. The inner mechanism for such phenomena is due to the complex violent interaction between the high-temperature and high-velocity turbulent plasma jet and the ambient atmosphere. Compared with traditional methods, the initial working conditions can be directly related to the temperature and velocity fields of the plasma jet by deriving basic boundary conditions.

Keywords

plasma spray / plasma jet / temperature field / velocity field

References

[1] FinckeJ. R., SwankW. D., BewleR. L., et al.. Diagnostics and control in the thermal spray process [J]. Surface and Coatings Technology, 2001, 146–147: 537-543

[2] EckerE. R. G., PfenderE.Advances in Plasma Heat Transfer[M], 1967, New York, Academic Press

[3] LeeY.-c.Modeling Work in Thermal Plasma Process[D], 1984, Minneapolis, University of Minnesota

[4] ChenX.Heat Transfer and Flow of High-temperature Ionic Gas[M], 1993, Beijing, Science Press

[5] ChangC. H., RamshawJ. D.. Modeling of nonequilibrium effects in a high-velocity nitrogen-hydrogen plasma jet[J]. Plasma Chemistry and Plasma Processing, 1996, 16(s1): 5-17

[6] DussoubsB., FauchaisP., VardelleA., et al.. Computational analysis of a three-dimensional plasma spray jet[C]. XXIII International Conference on Phenomena in Ionized Gases, 1997, Toulouse, Centre de Phys Plasmas et leurs Applications de Toulouse: 158-159

[7] NishiyamaH., KuzuharaM., SolonenkoO. P., et al.. Numerical modeling of an impinging dusted plasma jet controlled by a magnetic field in a low pressure[C]. Proceeding of the International Thermal Spray Conference, 1998, Nice, ASM International: 451-456

[8] DussoubsB., VardelleA., MariauxG., et al.. Modeling of plasma spraying of two powders[J]. Journal of Thermal Spray Technology, 2001, 10(1): 105-110

[9] ChenK.-f., FanJ.-r.Theory and Calculation of Engineering Gas-solid Multi-phase Fluid[M], 1990, Hangzhou, Zhejiang University Press

[10] XieH.Theory and Experimental Study of Plasma Jet with Particles[D], 1988, Beijing, Tsinghua University

[11] SuB.-z.Flow and Heat Transfer of Thermal Plasma[D], 1988, Beijing, Tsinghua University

[12] FanQ.-b., WangL., WangF.-c.. Numerical simulation of basic parameters in plasma spray[J]. Journal of Beijing Institute of Technology, 2004, 13(1): 80-84

[13] SchlichtingH., GerstenK., KrauseE., et al.Boundary-Layer Theory[M], 2000, New York, Springer-Verlag