Research of Double Circular-Arc Gear Fast Modeling Based on CATIA Secondary Development
Through the analysis of double circular-arc gear basic gear profile and the use of coordinate transformation method, this paper deduces the gear end-face equation of double circular-arc gear. With CATIA secondary development as a tool and double arc gear as the study object, accurately calculates the gear teeth curve profile and generate a double circular-arc gear one-time three-dimensional model by using the VB language programming, so as to improve design efficiency and accuracy, which lays a foundation for the strength analysis of the double arc gear, follow-up design and development of simulation, virtual assembly solid model.
Computerized design and simulation of meshing of modified double circular-arc helical gears by tooth end relief with helix
The contents of the paper cover: (i) computerized design, (ii) method for modification, (iii) simulation of meshing, and (iv) finite element analysis of the unmodified and modified double circular-arc gears. The approach proposed of tooth end relief with helix is based on the curves of circumferential displacement differences between before and after tooth surfaces entering in mesh and exiting out mesh. And the solutions under the conditions of different modification parameters are investigated. The results demonstrate that the method enables to decline transmission errors, decrease the maximum contact stress, lessen the tooth end stress, and cut down the circumferential displacement difference, effectively. Therefore, the purposes for modification of reducing noise and vibration and avoiding edge contact are achieved. In comparison with conventional double circular-arc gears, the developed theory is illustrated with numerical examples that confirm the advantages of the gear drives of the modified geometry.
Numerical and experimental investigation on air distributor design of fluidized bed reactor of sawdust pyrolysis
Abstract An improved biomass conversion in a lab-scale fluidized bed reactor (FBR) is achieved by optimizing the air distributor orifice size and number. Two approaches for introducing air were numerically and experimentally examined. These included perforated plate and downward orifice sparger. 3 mm and 5 mm orifice diameters, and 7, 9 and 13 holes were simulated at flow velocities of 2, 4, 6, and 8 times the minimum fluidization velocity, Umf. The simulation results revealed that increasing the orifice number has a positive effect on gas holdup, particularly for the perforated plate, which showed a uniform distribution of bubbles. The sparger configuration produced larger bubbles sizes, which could lead to better recirculation of solid flux, while stagnant particle zones were observed at the lower section of both distributors. A pyrolysis unit is also inserted at the top of freeboard of the FBR. For perforated plate with 6Umf, the pyrolysis process achieved thermal and cold gas efficiencies of 82.91% and 52.03%, respectively, while combustible gases with 41.6%mol CO, 8.7%mol CH 4 and 2.17%mol HC, were obtained. For sparger pipe and 6U mf _sp, 35.33 ppm NOx and 111 ppm SO 2 were measured in flue gas from combustion process at bed region.