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| Abstract No.: |
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Scheduled at:
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Monday, June 02, 2008, Room 05 3:00 PM
New Equipment 2
Latest developments in thermal spray equipment, modern multiple arc plasma guns, optimized powder feeder, new vacuum processes
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| Title: |
Gaseous pulse detonation spraying: current status, challenges and future perspective
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| Authors: |
Yuriy Kharlamov* / Ghulam Ishaq Institute of Engineering Sciences and Technology, Pakistan
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| Abstract: |
In a gaseous pulse detonation spraying unit (GPDSU) detonation is initiated in a barrel that servers as the combustor. The detonation wave rapidly traverses the barrel resulting in a nearly constant-volume heat addition process that produces a high pressure in the combustor and provides the formation of two-phase impulse flow and subsequent single layer coating deposition. In general, the near-constant-volume operational cycle of GPDSU provides a higher thermodynamic efficiency as compared to the conventional constant-pressure cycle. In order to use propagating detonations for thermal spraying and realize the GPDSU advantages, a number of challenging fundamental and engineering problems has yet to be solved. These problems deal basically with low-cost achievement and control of successive detonations and impulse two-phase jets formation in a spraying gun. To ensure rapid development of a detonation wave within a short cycle time, one needs to apply (1) efficient fuel and oxidizer gases supply systems to provide fast and nearly homogenous mixing of the components and their delivery to the detonation chamber (DC); (2) low-energy source for detonation initiation to provide fast and reliable detonation onset; (3) geometry of the combustion chamber to promote detonation initiation and propagation at lowest possible pressure loss and to ensure high operation frequency; (4) efficient powder supply system to provide fast and required solid particles distribution into barrel for optimal interaction between solid and gaseous phases; (5) cooling technique for rapid, preferably recuperative, heat removal from the walls of DC and adjoining channels and components to ensure stable operation and avoid premature ignition of fuel-oxidizer mixture leading to detonation failure; (6) efficient integration of GPDSU barrel with inlets and nozzles to provide high performance; (7) control methodology that allows for adaptive, active control of operation process to ensure optimal performance at variable spraying conditions. The operation of multi combustion chambers GPDSU configurations at high detonation-initiation frequency (about 100 Hz and over) can produce a near-constant high-velocity gas flow.
Current understanding and thermodynamic grounds for gaseous detonation-based spraying, principles of practical implementation of the detonation-based thermodynamic cycle, and various operational constraints of GPDSU are discussed.
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