No abstract

A new numerical method, verified by the analytical solution of the weight functions and experimental paths, is developed to evaluate the crack initiation and propagation generally in mixed mode (I-II). This numerical method combining the interaction integral method and the maximum tangential stress (MTS) criterion is based on the finite element method of secondary development. The influence of combined confining pressure and diametric forces on crack propagation trajectories for CCBD specimens are studied. It is indicated that the crack propagation direction independent of the confining pressure keeps the same with the line of original crack as the loading angle is equal to [Formula: see text]. But when the loading angle is greater than [Formula: see text], the curvature of the curve trajectory in the early stage of crack propagation increases with a larger confining pressure. Further, it is found that larger values of the loading angle and relative length will make the effect of confining pressure more significant at the early stage of crack growth.

No abstract

An experimental investigation of phase distribution for subcooled flow boiling in an inclined circular tube (i.d. 24 mm) was conducted in this paper. The local interfacial parameters were measured by a double-sensor optical fiber probe, and the measurements were performed on three different directions in the inclined tube cross section. The experiment shows that the phase distribution under the inclined condition is different from the phase distribution under the vertical condition. The profiles skewed highly for 90°and 45°direction in the tube cross section, whereas the profile was also symmetrical at 0°direction. These results can be explained by the fact that buoyancy caused the bubbles to move toward the top of the tube cross section under inclined condition. In addition, the typical distributions were also influenced by the inclination angles.

The experimental study on the pressure drop characteristics of the gas-liquid two-phase flow under heaving condition is carried out. The influence of the heaving condition on the transient and time-averaged two-phase pressure drop is obtained. On this basis, the calculation model of two-phase transient pressure drop under heaving condition is constructed, which is in good agreement with the experimental results. According to the experimental data and the results of the model calculation, the influence of heaving condition on the pressure drop components is analyzed. It is found that the transient total pressure drop is fluctuating periodically, while the time-averaged value is nearly the same as that under static condition. Further analysis shows that the friction pressure drop and the gravity pressure drop are basically the same under heaving condition. The fluctuation of additional pressure drop introduced by heaving motion is the reason for the periodic fluctuation of the total pressure drop.