Nozzle

About: Nozzle is a research topic. Over the lifetime, 158675 publications have been published within this topic receiving 893026 citations. The topic is also known as: spout.

In-situ monitoring of polymer flow temperature and pressure in extrusion based additive manufacturing

Abstract: We demonstrate a novel Fused Filament Fabrication (FFF) nozzle design to enable measurements of in-situ conditions inside FFF nozzles, which is critical to ensuring that the polymer extrudate is flowing at appropriate temperature and flow rate during the part build process. Testing was performed with ABS filament using a modified Monoprice Maker Select 3D printer. In-situ measurements using the printer’s default temperature control settings showed an 11 °C decrease in temperature and significant fluctuation in pressure during printing as well as fluctuations while idle of ± 2 °C and ±14 kPa. These deviations were eliminated at lower flow rates with a properly calibrated proportional–integral–derivative (PID) system. At the highest tested flow rates, decreases in melt temperature as high as 6.5 °C were observed, even with a properly calibrated PID, providing critical insight into the significance of flow rate and PID calibration on actual polymer melt temperature inside the FFF nozzle. Pressure readings ranging from 140 to 6900 kPa were measured over a range of filament feed rates and corresponding extrusion flow rates. In-situ pressure measurements were higher than theoretical predictions using a power-law fluid model, suggesting that the assumptions used for theoretical calculations may not be completely capturing the dynamics in the FFF liquefier. Our nozzle prototype succeeded in measuring the internal conditions of FFF nozzles, thereby providing a number of important insights into the printing process which are vital for monitoring and improving FFF printed parts.

Main stage fuel mixer with premixing transition for dry low Nox (DLN) combustors

Abstract: A main stage fuel mixer that reduces NO x and CO emissions of a gas turbine combustor by providing a more homogeneous fuel/air mixture for main stage combustion is provided. A gas turbine combustor according to the present invention includes a nozzle housing having a nozzle housing base, a plurality of main nozzles, and a main stage fuel mixer. A main combustion zone is located adjacent to the nozzle housing. Each main nozzle extends through the nozzle housing and is attached to the nozzle housing base. The main stage fuel mixer has a plurality of inlets, each of which is adapted to receive a flow of gas, and an outlet adjacent to the main combustion zone. The main stage fuel mixer has a plurality of transition ducts, each associated with one inlet. Each transition duct provides fluid communication from the inlet associated with the transition duct to the outlet.

Fuel nozzle guide heat shield for a gas turbine engine

Abstract: Fuel Nozzle Guide Heatshield For A Gas Turbine Engine Abstract This invention relates to the construction of the heatshield of a fuel nozzle guide of a turbine power plant and provides the separation of the higher temperature operating structure from the cooler structure to assure that the expansion and contraction is permitted without undue restrain for increasing its durability.

Throughput enhancement of parallel step emulsifier devices by shear-free and efficient nozzle clearance

Abstract: Step emulsification is an attractive method for production of monodisperse drops. Its main advantage is the ability to parallelize many step emulsifier nozzles to achieve high production rates. However, step emulsification is sensitive to any obstructions at the nozzle exit. At high production rates, drops can accumulate at nozzle exits, disturb the formation of subsequent drops and impair monodispersity. As a result, parallelized step emulsifier devices typically do not work at maximum productivity. Here a design is introduced that parallelizes hundreds of step emulsifier nozzles, and effectively removes drops from the nozzle exits. The drop clearance is achieved by an open collecting channel, and is aided by buoyancy. Importantly, this clearance method avoids the use of a continuous phase flow for drop clearance and hence no shear is applied on the forming drops. The method works well for a wide range of drops, sizing from 30 to 1000 μm at production rates of 0.03 and 10 L per hour and achieved by 400 and 120 parallelized nozzles respectively.