Fluid flow and heat transfer mechanisms in the spray deposition of tubularpreforms

A combined experimental and numerical investigation hto the fluid flow and heat transfer processes that take place in the spray deposition of tubular preforms is presented The work is concerned principally with impingement me chanisms at jet diameter to target distances that are large in comparison w ith previous reported studies. The experimental investigation required the design of a novel heat transfer meter that was capable of resolving the hea t transfer coefficient within 2.5 per cent The experiment gave a new correl ation for stagnation heat transfer, similar in form to correlations that ha ve been published for small jet diameter to target distance values. The exp eriments also showed the presence of skewing of the heat transfer coefficie nt in the deposition zone due to its tapered nature. A finite volume based model of the deposition chamber was developed and run to compared with the experimental data. This model was found to yield trends similar to those me asured experimentally, thus confirming its qualitative capability. However the absolute values of heat transfer coefficient that were computed were si gnificantly lower than measured values. This points to the requirement to c onsider alternative computing schemes and to investigate the methods of rep resenting the heat transfer mechanisms at the physical boundaries, particul arly at the preform surface.