長い噴射管をもつコールドスプレーノズル内の貯気温度の推算法に関する研究

Abstract

A gas dynamic method, to estimate the mixed-mean gas temperature which is called stagnation temperature, in a stagnation chamber of a cold spray nozzle with a long injection-pipe, is proposed. The method does not use temperature measured by thermocouple but mass flow rate of the process/carrier gases and stagnation pressure upstream of the nozzle. The stagnation temperatures estimated by the present method were validated by comparing them with measured values using a coiled sheath-type φ 0.5mm thermocouple, inserted in the stagnation chamber of the nozzle. The gas flow experiment of cold spray was conducted under the conditions of gas pressure up to 0.96MPa, and heater-exit gas temperature up to 673K. The working gases selected were air and helium. The species of the process gas and the carrier gas was the same. The ratio of the mass flow rate of the carrier gas against that of the total mass flow rate selected was 0.2. The comparison of the estimated and measured stagnation temperatures shows that the estimation error of the present method is less than 4% for air, and less than 5% for helium gas.