A Method of Reducing Trace Deviation of the Flow Field in the Model Experiment: An Example of a Tundish

The tracer is widely used in model experiments to obtain the key flow characteristics of reactors. However, it was found that the dead zone fraction varies with the tracer density in the experiment with the tundish water model (TWM). The flowing behavior of different density tracers in TWM was simulated by OpenFOAM v8. The centroid height deviation of the tracer and the volume-average additional velocity ratio are proposed as the indexes of the effect of gravity on the tracer and the effect of the tracer on the original flow flown, respectively. In the first 30 seconds, the former exceeds 40 pct for the densest tracer, while the latter is about 4.0 pct. The results indicate that gravity is the key factor of the tracing deviation. To minimize the density difference, a method for preparing the tracer is suggested. A relationship between the mixture density and the mass fraction of KCl and ethanol is fitted as \(\rho = 0.99196 + 0.66575w_{{{\text{KCl}}}} \, {\text{pct}} - 0.16261w_{{{\text{ethanol}}}} \, {\text{pct}}\) $\rho =0.99196+0.66575w_{\text{KCl}}\text{pct}-0.16261w_{\text{ethanol}}\text{pct}$ .