Abstract
An analysis of a high-velocity oxygen fuel thermal spray torch is presented using computational fluid dynamics (CFD). Three-dimensional CFD results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco diamond jet rotating wire torch, but wire feed is not simulated. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Argon is injected through the center of the nozzle. Premixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled assuming instantaneous chemistry. A standard, two-equation, k-e turbulence model is employed for the turbulent flow field. An implicit, iterative, finite volume numerical technique is used to solve the coupled conservation of mass, momentum, and energy equations for the gas in a sequential manner. Computed flow fields inside and outside the aircap are presented and discussed.
Highlights
Spray torch is presented using computational fluid dyaamics (CFD).Three-dimensional CFD results are presented for a med aircap used for coating interior surfaces such as engine cylinder bores
The combustion process produces temperatures in the range of 3000 K inside the thermal spray device which result in supersonic streams exterior to the device
CFD simulationshave been done in two-dimensions, primarily on axisymmehic thermal spray devices both with and without powder injection.Thefirst CFD simulation of theHVOFprocess was conductedby Power et al.I2 and Smith et al.%ey modeled the internal and external flow of the Metco Diamond Jet torch with a powder feeder
Summary
Theydirection,by 0.406 mm (0.016 in.) from the centerline of the conical portion of the aircap This shift provides more aircoolingflow to the bottom portion of the aircap where the heat transfer rates will be higher, primarily in the curved =@on of the aircap near the exit. Both the premixed fuel/mygen and the air cooling streams enter the aircap at an angle of 5 degrees, which is the half angle of the conicalse~ti[011]. Radial grid clustering was performed in the regions of the shear layers surrounding the fuel/oxygen inlets and in the boundary layer on the d a c e of the aircap.
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