Evaluation of flow stability and heat transfer coefficient distribution around heated substrate

Abstract

This study investigates the oscillation phenomenon in a locally heated cylindrical flow channel simulating low-temperature ozone CVD with an impinging jet stream. The results show that when the heated substrate is placed in the downward direction (+g configuration), a periodic oscillating flow with a period of about 2.7 seconds is observed between the gas inlet and the heated substrate under specific conditions (d_H = 50 mm, Q = 6 SLM, and Q = 9 SLM). On the contrary, when the heated substrate was placed face up (-g configuration), no oscillations were observed, resulting in a stable flow. We used the experimental setup to visualize the flow pattern and analyze the periodic nature of the flow in different configurations. The results highlight the importance of substrate orientation in determining flow stability in CVD processes, with upward facing configurations promoting more stable flow conditions. This study demonstrates how the interaction of natural and forced convection can lead to complex flow dynamics depending on the orientation of the heated substrate.