EXPERIMENTAL STUDY ON FACTORS AFFECTING THE END EFFECT FOR NITROGEN FLOW IN MICRO TUBE

In this work, we studied factors affecting the end effect in microtubes by conducting nitrogen microscale flow experiments in 31~100 μm tubes under the conditions of 5~20 MPa and 25~60℃. We proposed the double tube-length differential pressure calculation method for end-effects induced additional differential pressure Δp_end. Using this method, it is found that there is a negative correlation between Δp_end and tube diameter d, and Δp_end increases monotonically with the flow velocity v. The effect of pressure on Δp_end is not significant under low flow rate conditions, however Δp_end increases with increasing pressure under high flow rate conditions. Under the experimental conditions in this paper, temperature has little effect on Δp_end. Finally, we established an empirical model to describe the relationship between Δp_end and v, d.