Hydrodynamic Behavior of Liquid Quenchants In the Vicinity of Quench Probes

Heat extraction in quench probes is a complex phenomenon due to the strong correlation between the hydrodynamics of the quench bath and the phase transformations suffered by the quenchant. In turn, the hydrodynamic behavior in the vicinity of quench probes depends on the geometry and the physical properties of the quench bath. Building on previous findings, in this work we report CFD simulations of the pressure and velocity fields, as well as the streamlines, in the vicinity of cylindrical probes of various geometries. In particular, flat-end, conical-end, spherical-end and chamfered probes were studied. The simulations were carried out for probes located concentrically in a cylindrical tube with water flowing parallel to the probe longitudinal axis. An experimentally determined velocity profile (corresponding to fully-developed flow in a 44 mm-dia. tube) was used as boundary condition few centimeters bellow the probe tip. The system was assumed to be at room temperature in order to separate the hydrodynamic and the thermal effects. To validate the model, cellophane ribbons were attached to the probe tip in order to trace the streamlines near that region and compare them to their computed counterpart. From the simulations, it was concluded that the conical-end cylindrical probe generates hydrodynamic conditions particularly suitable for estimating the heat transfer boundary condition at the probe-liquid interphase as for studies on wetting front kinematics.