The effect of geometrical parameters on the flow field of an opposed jet rim mix head: Equal flow and matched fluids

AbstractThe effect of geometrical parameters on the flow field present in the mix head used in reaction injection molding (RIM) are presented for Red (Red = 4Q/πdv, nozzle diameter d, fluid kinematic viscosity v and the volumetric flow rate Q through the nozzle) representative of commercial practice. Quantitative velocity measurements of the flow field in a mix head have not been reported in the literature despite the extensive use of the mix head for reaction injection molding. Flow visualization and velocity measurements using a laser Doppler anemometer have been obtained for different values of geometrical parameters such as mix chamber diameter (D), distance from the nozzle inlet to the closed end of the chamber (H), and nozzle needle position (N). The ratio of the mix chamber to nozzle diameter (d) (D* = D/d) was a significant parameter affecting the flow field. The distance from the impingement point to the closed end of the chamber was found to have little effect on the observed flow field beyond the impingement area. A nozzle needle position that partially constricted the nozzle opening was found to decrease the axial distance to unidirectional flow within the mix chamber.

The effect of geometrical parameters on the flow field of an opposed jet rim mix head: Equal flow and matched fluids Journal Articles