The applicability of the numerical method for the heat transfer process of airflow

Abstract

To improve the accuracy of air flow and heat transfer in numerical study, the research on viscous model and data processing method of compressible air is conducted. The average heat transfer coefficients of airflow in the heating tube are obtained using the computational fluid dynamics method with Re ranging from 10 000 to 400 000 and temperature ranging from 450 K to 1 200 K. To solve the key problems of airflow and heat transfer, such as compressibility, qualitative temperature, and viscous heating effect, the average heat transfer coefficient of heated air pipe flow under different turbulence models is obtained. Combined with the classical heat transfer relation, the data processing method is determined, and the characteristics of the influencing factors of the viscous heating effect are discussed. The results indicate that the realizable k-ε model can simulate the high-temperature and high-speed compressible airflow. The deviation of the heat transfer correlation between the numerical method and Gnielinski correlation is determined to be within 10% using the average temperature of the inlet and outlet as qualitative temperature, which is acceptable. The viscous heating effect, which will decrease Nu under high Re conditions, should be considered. This study provides a basis for the accurate calculation of the heat transfer characteristics of air.