ガスジェット冷却特性に及ぼすガス混合比率の影響

抄録

Gas jet cooling is widely used because the device is simple, it is possible to prevent oxidation and a uniform cooling ability can be obtained with thin steel sheets. Because the gas jet cooling ability is affected by physical properties of the gas such as the mixed gas ratio, quantitative evaluation of the influence of these factors is very important. However, few studies concerning prediction of the mixed gas jet cooling ability in atmospheres with different concentrations have been published.

In this research, the results of experiments and fluid analyses with an air-helium gas jet in an air atmosphere were compared with the results obtained with Martin's non-dimensional empirical equations. As the nozzle condition, a single round nozzle with a tapered shape was examined. The helium concentrations with respect to air were 0, 20, 50 and 100 vol%, and the pressure conditions were 3 and 5 kPa.

Compared with the experimental results, Martin's equations largely predicted improvement of cooling performance with increasing helium concentrations. In the analyses, mixing with air increased as the helium concentration decreased.

The trend of divergence between the experimental and predicted cooling ability was clearly presented in this research. The results of this study make it possible to improve the accuracy of predictions of the impinging jet cooling ability with different concentrations between an atmosphere and a gas jet.