Abstract
A mathematical model was developed to describe the gas dynamics and heat-transfer mechanism in the gas/particle flow of high- velocity oxyfuel (HVOF) systems. A numerical solution was carried out using a PC- based computer program. One- dimensional predictions of the temperature and velocity profiles of gas and particles along the axis of flow were obtained to conduct cost- effective parametric studies and quality optimization of thermal spray coatings produced by HVOF systems. The numerical computer model allows for the variation of the HVOF system parameters, such as air/fuel ratio and flow rates, cooling water inlet temperature and flow rate, barrel length, standoff distance, particle size, and gun geometry.
Because of the negligible volume of the powder relative to the gas, the gaseous phase was modeled as continuous nonadiabatic, and friction flow with variable specific heats and changing cross- sectional areas of flow. The generalized continuity, momentum, and energy equations with the influence parameters were used to model the gaseous flow regime and predict its thermodynamic properties. Empirical formulas for the mean axial decay of both velocity and temperature in the supersonic jet plume region were generated from published measurements of these parameters using laser Doppler velocimeter and Ray leigh scattering techniques, respectively. The particle drag and heat- transfer coefficients were calculated by empirical formulas in terms of Reynolds, Nusselt, and Prandtl numbers to evaluate both the momentum and heat transferred between the combustion gases and the powder particles. The model predictions showed good agreement with the particle and gas temperature and velocity measurements that are available in the literature.
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F. Zimmerman, NASA/Marshall Space Flight Center, private communication, 1995
R.L. Daniel, H.L. Sanders, and M.J. Mendrek, Replacement of Environmentally Hazardous Corrosion Protection Paints on the Space Shuttle Main Engine Using Wire Arc Sprayed Aluminum, Thermal Spray Industrial Applications, C.C. Berndt and S. Sampath, Ed., ASM International, 1994, p 93–98
D. Rome, Naval Surface Warfare Center, private communication, 1993
P. Siitonen, T. Konos, and P. Kettunen, Corrosion Properties of Stainless Steel Coatings Made by Different Methods of Thermal Spraying, Thermal Spray Industrial Applications, C.C. Berndt and S. Sampath, Ed., ASM International, 1994,p 105–110
R. Shah, K.-C. Wang, K. Parthasaathi, J. Jo, and E. Onesto, Towards Manufacturing High-Quality Thermal Spray Coatings, Thermal Spray Industrial Applications, C.C. Berndt and S. Sampath, Ed., ASM Inter- national, 1994, p 675–681
O. Knotek, E. Lugscheider, P. Jokiel, U. Schnaut, and A. Wiemers, Chromium Coatings by HVOF Thermal Spraying: Simulation and Practical Results, Thermal Spray Industrial Applications, C.C. Berndt and S. Sampath, Ed., ASM International, 1994, p 179–184
W.D. Swank, J.R. Fincke, D.C. Haggard, G. Irons, and R. Bullock, HVOF Particle Flow Field Characteristics, Thermal Spray Industrial Applications, C.C. Berndt and S. Sampath, Ed., ASM International, 1994, p 319–324
CM. Hackett and G.S. Settles, Turbulent Mixing of the HVOFThermal Spray and Coating Oxidation, Thermal Spray Industrial Applications, C.C. Berndt and S. Sampath, Ed., ASM International, 1994, p 307–312
H. Tawfik and F. Zimmerman, “Quality Optimization of Thermally Sprayed Coatings Produced by HVOF Systems Using Mathematical Modeling,” paper presented at NASA/ASEE Summer Faculty Fellowship Program, NASA Marshall Space Flight Center, 1994
TAFA, Inc., Technical Specifications JP 5000
J.C. Lau and P.J. Morris, Measurements in Subsonic and Supersonic Free Jets Using a Laser Velocimeter, J. Fluid Mech., Vol 93, Part 1, 1979, p 1–27
N.T. Lagen and J.M. Sciner, “Evaluation of Water Cooled Supersonic Temperature and Pressure Probes for Application to 2000 °F Flows,” NASA Technical Memorandum 102612
L.Y. Jiang and J.P. Sislian, “LDV Measurements of Mean Velocity Components and Turbulence Intensities in Supersonic High-Temperature Exhaust Plumes,” AIAA-93-3067, American Institute of Aeronautics and Astronautics, 1993
W.L. Oberkampf and M. Talpallikar, Analysis of a High Velocity Oxygen-Fuel (HVOF) Thermal Spray Torch, Part 1: Numerical Formula- tion, Thermal Spray Industrial Applications, C.C. Berndt and S. Sampath, Ed., ASM International, 1994, p 381–386
M.L. Thorpe and H.J. Richter, A Pragmatic Analysis and Comparison of HVOF Processes, J. Therm. Spray Technol., Vol 1 (No. 2), 1992, p 161–170
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Tawfik, H.H., Zimmerman, F. Mathematical modeling of the gas and powder flow in HVOF systems. J Therm Spray Tech 6, 345–352 (1997). https://doi.org/10.1007/s11666-997-0069-6
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DOI: https://doi.org/10.1007/s11666-997-0069-6