The same dimensions and pressure drop as that of a straight tube should have same mass flow rate through bend tube if the flow is fully attached without any secondary flow. Therefore, lower mass flow rate through the bend tube indicates that the flow is with secondary flow due to bend and has to overcome additional resistance due to secondary flow causing the LDC1267 in mass flow rate. This conclusion (on the basis of measurements and analytical solution) further reinforces the numerically obtained streamlines and velocity vector plots showing the secondary flows (Fig. 11).
In this work, experiments for low pressure nitrogen gas flowing through three different bend test sections of diameters (8, 13 and 20 mm) and lengths (208, 213 and 220 mm) are performed. The measurements cover part of the continuum and slip flow regimes (0.0003 < Kn < 0.0385; 0.27 < Re < 418.5). The static pressure measurements along the inner, outer and top walls are undertaken and analyzed to understand the flow behavior. The results are compared with analytical solution obtained for flow in a straight tube under similar flow conditions. The velocity field is thermiogenesis obtained through numerical analysis for better understanding of the flow behavior near the bend.