A computational study of pulsed detonation thermal spraying

Pulsed detonation thermal spraying is a process by which a powdered material with special properties is deposited on a substrate to improve its surface properties or to produce a protective coating layer. The process utilizes the high-energy concentration and extreme gas velocities associated with the detonation phenomena to propel the powdered material to high velocities and temperatures that are adequate to produce quality coatings at impact on the target surface.; The importance of the work addressed here arises from the need to have a theoretical multi-dimensional transient flow model with reasonable assumptions that can reveal some important features of pulsed detonation thermal spraying. A multi-component, two-dimensional axisymmetric transient dusty detonation model with variable gas properties was developed to analyze this process. Both one-way and two-way couplings between the gas and the particulate phase are considered.; The time splitting technique is used to split the gas-phase governing equations into homogenous and non-homogenous subsystems of equations. A high-resolution shock capturing numerical technique is used to solve the homogenous part of the gas-phase governing equations. The technique utilizes the flux vector splitting method in conjunction with a two-step Runge-Kutta scheme. The ordinary differential equations representing the non-homogeneous part of the gas-phase equations and the particulate phase governing equations are solved by an implicit method.; The analysis presented here shows that the shock reflection phenomena have negligible effects on the spraying process. Excessive mass loading of the particulate phase results in severe detonation attenuation and can severely degrade the process. The geometry of the system, the reactive mixture composition, the particulate phase physical properties and the loading locations of the sold phase are key parameters in pulsed detonation thermal spraying.; One cycle of detonation thermal spraying occurs on a time scale of the order of a millisecond due to the extreme transient effects associated with detonation. Thus, an extreme control of the process variable parameters is required to have a successful detonation coating process.