Effect of Initial Temperature of a Cylindrical Steel Block on Heat Transfer Characteristics of Staggered Array Jets During Water Jet Quenching

The effects of initial temperature of a cylindrical stainless steel block on heat transfer characteristics are investigated for a staggered-array circular jet during water jet quenching. The initial temperature of a block is set to change from 500 degrees C to 1,000 degrees C by an induction heating method. Transient temperature measurements are made at discrete locations near the surface along radial direction. The surface temperature and heat flux distributions can be numerically estimated by solving a two-dimensional axisymmetric inverse heat conduction problem. The heat transfer characteristics of staggered-array jets in the impingement jet zone are compared with those in the wall jet flow zone. The effect of initial temperature of the test block in the nucleate boiling regime is also examined to solve the difficulties in most water jet quenching of hot steel. The area-averaged heat flux curves are used to evaluate representative cooling performance of staggered-array jets. The maximum area-averaged heat flux linearly increases as the initial temperature of the test block increases. Regardless of initial temperature of the test block, the nucleate boiling regimes are remarkably similar to each other. The area-averaged heat flux is also provided for fully developed nucleate boiling.