RESUMO
This study aims to experimentally and theoretically investigate the roles of a threaded nozzle and yield stress in the coaxial air blast atomization of a gelled jet by means of rheological tests and high-speed flow visualization techniques. Similar to the breakup types of Newtonian fluids, a gelled jet will gradually exhibit an oscillation mode, membrane-type breakup, fiber-type breakup and a superpulsating submode as the airflow velocity increases. The transition conditions for each type are determined and plotted in the dimensionless map of We-Oh. For the jet spray angle, the maximum occurs when We = 600 and is clearly enlarged by the gas-side thread in the nozzle. The numerical results of the linear stability analysis indicate that a smaller dominant unstable growth rate is acquired by swelling the yield stress, while the higher dominant unstable growth rate and truncated wavenumber appear as the rotational airflow is acquired through the gas-side threaded nozzle.
RESUMO
Traditional calibration technology has been widely used in measurement and monitoring; however, there are limitations of poor calibration accuracy, which can not meet the accuracy requirements in some scenarios. About this problem, we proposed a grey wolf optimization algorithm based on levy flight and mutation mechanism to solve camera internal parameters in this paper. The algorithm is based on the actual nonlinear model, which takes the minimum average value of reprojection error as the objective function. The grey wolf position is randomly generated within a given range. Then, the grey wolf optimization algorithm based on levy flight and mutation mechanism is used to iteratively calculate the optimal position, which is the internal parameters of cameras. The two groups of experimental data were performed to verify the algorithm. The result shows better effectiveness and calibration accuracy of the proposed algorithm compared with other optimization methods.