Адиабатическая газодинамическая модель для специфической геометрии сопла холодного напыления низкого давления

Abstract

Изучение газодинамических характеристик процесса, как правило, проводится через адиабатические газодинамические модели и гидродинамические вычисления. В данной работе, представлена инновационная адиабатическая газодинамическая модель для расчета энергетических параметров потока в сопле при использовании метода холодного напыления низкого давления. Адиабатическая газодинамическая модель, представленная в этой работе, предназначена для изучения неправильной геометрии сопла. Результаты параметров потока газа через сопло используются для расчета скорости частиц и температуры коммерчески доступных порошкообразных материалов.The study of the gas dynamic process through a DeLaval nozzle is one of the main subjects aimed for the optimization of the Cold Spraying technology. The study of the gas dynamic characteristics of the process is generally achieved through isentropic gas dynamic models and computational fluid dynamics. A novel approach for the calculation of the energy parameters of a gas being expanded through a DeLaval nozzle is presented. This approach is capable of calculating the gas velocity and temperature for any cold spraying nozzle geometry. The model can be used as well in order to calculate the particles acceleration and heat transfer between a particles and the gas stream during their residence inside the cold spraying nozzle. In this work, the effect of the boundary layer created inside the nozzle is studied using a pitot tube. The experimentation with the pitot tube shows a clear effect of the boundary layer on the Mach number development through the nozzle. It was found that for the studied cold spraying nozzle a Mach number of ~1.55 is developed. Calculations for the acceleration of Nickel, Aluminum and Copper particles were performed for the studied nozzle. The calculations have shown that the acceleration of particles is directly affected by the air density that decreases during its expansion through the cold spraying nozzle. The present model can be used in the future for the optimization of particle acceleration taking into account the effect of gas velocity and density through a DeLaval nozzle.