The sphere melting technique: Mathematical modelling and experimental measurements.

摘要

The present investigation focuses on the application of the sphere melting technique to the measurement of velocity and the measurement of the Nusselt number in high temperature liquid metals. When a metallic sphere is immersed in a bath of the same composition as the sphere, the melting time depends on the sphere's material, size, and the bath's temperature and flow condition. To find the relationship between these parameters, a mathematical model is developed.; There is no established method to measure the velocity in high temperature liquid metals. The total melting time of a metal sphere immersed in a bath can be correlated with the velocity and temperature of the bath. This can be used to infer the magnitude of velocity inside the bath. An experimental apparatus is constructed to measure the melting times of Aluminum and AZ91 spheres as a function of the bath's temperature and velocity. In order to measure the direction of velocity in a liquid metal, a special device with several melting probes is designed, developed and constructed. The applicability of the method in different liquid metal systems is analyzed.; In order to calculate the dimensionless heat transfer coefficient in a liquid metal, a procedure is developed using the results that can be obtained using the sphere melting technique. Dimensionless correlations for natural and forced convection are obtained from results from the numerical model and from the experimental measurements carried out for this investigation. A comparison between the results obtained and from other authors proves that the heat transfer coefficient must be measured in a material with similar Prandtl number. The buoyancy parameter that limits the influence of natural convection in the solution is calculated from the experimental measurements. The present investigation focuses on the application of the sphere melting technique to the measurement of velocity and the measurement of the Nusselt number in high temperature liquid metals. When a metallic sphere is immersed in a bath of the same composition as the sphere, the melting time depends on the sphere's material, size, and the bath's temperature and flow condition. To find the relationship between these parameters, a mathematical model is developed.