THE BIRD-CAGE METHOD USED FOR MEASURING CYLINDRICITY. A PROBLEM OF OPTIMAL PROFILE MATCHING.
The bird-cage method used for measuring cylindricity is reported to be the most effective, as it pro- vides the most detailed information about an analyz ed ob- ject. The average values of profiles measured with the cross- section and the generatrix methods may differ sligh tly, yet this may result from some design imperfections of t he measurement instruments used. In this study, the pr oblem of optimal profile matching is formulated and solved. As a result, the differences between the values of the r egistered profiles at the points of intersection of the scann ing trajecto- ries can be minimized.
Assessing cylindricity for oblique cylindrical features
This research investigates the algorithmic aspect of cylindricity assessment. With the surface points measured with coordinate measuring machines (CMMs), cylindricity can be assessed under different kinds of reference cylinders. In order to explore the full capability of CMMs, supplementary methodologies for finding a fine-tuned axis of the cylinder have been developed, including rotational devices, quasi-linear equations and complicated procedures. This research derives a mathematical model so that the axis of the reference cylinder can be tuned algorithmically. The global optimum of the model, which yields the assessment of cylindricity, is computed by using a simulated annealing algorithm, namely Hide-and-Seek.
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.