Coupled Analysis of the Film-Cooling and Infrared Characteristics of an Axisymmetric Vectored Nozzle

This study adopts a narrow band model to investigate the cooling and radiation of a vectoring nozzle and to compute the gas spectral characteristic in infrared band. The radiative heat transfer between the hot gas and the wall is considered with an enclosure model. The calculation of film cooling is performed through a cooling effectiveness method. A coupled heat balance equation of heat flux and wall temperature is established on the multilayer structure of the nozzle, including the wall, heat shield, and outer shield, and a Newton-Raphson scheme is taken for solution. Temperature on the expansion part of an experimental nozzle in NASA TN D-1988 is investigated for verification. Another vectoring nozzle with a multirow of film cooling is also investigated. This study shows that the film in the heat shield remarkably cools the convergent part of the nozzle, thereby increasing the temperature on the expansion part of the nozzle. The deflection of the nozzle can change the distribution of the wall temperature and the radiation on the expansion part, which is lower on the deflection side than on the opposite side. The radiation from the nozzle outlet is high, particularly along the deflection direction in the rear hemisphere.

Wear Modeling of Steel Surfaces to the Flow under Pressure of Melts Polymers with SGF

Consequences of the wear processes at screws and barrels of injection machines and extruders for processing of plastics reinforced with short glass fibers, arise after a longer time (10,000 cycles). Because of this they are working that through appropriate modeling attempts on the profits to be obtained in a short time as much information relating to both the mechanisms of wear and its size, so that the effect can be easily confuted in practice. Starting from the idea that the greatest pressure and velocity of composite melted is in the die nozzle, was an experimental nozzle with wear samples of sizes and weights which can be measured with precision as good. For a larger accuracy of measurements, we used a method for radiometric measuring, extremely accurate. Different nitriding steels have been studied as nitriding treatments, as well as some special steels and alloyed steels. Besides these, there have been preliminary attempts made to describe and checking corrosive action of termoplastelor on metals. This was another way of checking the wear testing of the samples semi-cylindrical wear samples, which served to simulate the wear of the top layer of the barrel and screw. The first results showed that wear increases depending on the increased pressure. One of the findings is that in similar conditions of injection, with the same content of glass fiber, polyamide 6.6 produces a wear greater than polycarbonate. It was also found that increasing the concentration of glass fibres increase the surfaces wear of barrels and screws.

About an Experimental Modeling of Steel Surfaces Wear in Injection of Plastic Composites with Short Glass Fibres

Consequences of the wear processes at screws and barrels of injection machines and extruders for processing of plastics reinforced with short glass fibers, arise after a longer time (10,000 cycles). Because of this they are working that through appropriate modeling attempts on the profits to be obtained in a short time as much information relating to both the mechanisms of wear and its size, so that the effect can be easily confuted in practice. Starting from the idea that the greatest pressure and velocity of composite melted is in the die nozzle, was an experimental nozzle with wear samples of sizes and weights which can be measured with precision as good. For a larger accuracy of measurements, we used a method for radiometric measuring, extremely accurate. Different nitriding steels have been studied as nitriding treatments, as well as some special steels and alloyed steels. Besides these, there have been preliminary attempts made to describe and checking corrosive action of thermoplasts on metals. This was another way of checking the wear testing of the samples semi-cylindrical wear samples, which served to simulate the wear of the top layer of the barrel and screw. The first results showed that wear increases depending on the increased pressure. One of the findings is that in similar conditions of injection, with the same content of glass fiber, polyamide 6.6 produces a wear greater than polycarbonate. It was also found that increasing the concentration of glass fibres increase the surfaces wear of barrels and screws.

Air Flow in Yarn Texturing Nozzles

The air-jet texturing process, a purely mechanical means of texturing continuous filament yarns, is described. Industrial texturing nozzles are reviewed and categorized in two groups, either as converging-diverging or cylindrical type nozzles. A mathematical model is developed for the complex airflow in cylindrical type texturing nozzles, and experimental data obtained from various nozzles verify the flow predicted by this model. The mathematical model is also shown to be in good agreement with the data obtained from a modified experimental nozzle, which has a trumpet shaped diverging exit. Further experimental work with a scaled-up model of a typical industrial texturing nozzle is also reported.