MovingStrip: Investigation of heat transfer in the impingement flow on moving metal strips

Effi­ci­ent nozz­le sys­tems for hea­ting or rapid coo­ling of metal strips are gene­ral­ly desi­gned using for­mu­lae from the lite­ra­tu­re and mea­su­re­ments of the heat trans­fer coef­fi­ci­ent. Howe­ver, the­se do not direct­ly take into account the strip move­ment and the asso­cia­ted chan­ges in the tem­pe­ra­tu­re boun­da­ry lay­er. The strip move­ment gives rise to what is known as a Sakia­dis flow, which increa­ses the tem­pe­ra­tu­re of the boun­da­ry lay­er on the strip and ther­eby redu­ces con­vec­ti­ve heat trans­fer at the strip. Preli­mi­na­ry inves­ti­ga­ti­ons at the IOB sug­gest that the­re are inter­ac­tions bet­ween the Sakia­dis flow and the impinging jet gene­ra­ted by the nozz­le system.

As part of the rese­arch pro­ject, both expe­ri­men­tal and nume­ri­cal inves­ti­ga­ti­ons into the influence of strip move­ment on heat trans­fer will be car­ri­ed. This requi­res the modi­fi­ca­ti­on of an exis­ting expe­ri­men­tal test rig for stu­dy­ing tran­si­ent strip move­ment, as well as the deve­lo­p­ment of a nume­ri­cal model. Sub­se­quent­ly, a com­pre­hen­si­ve expe­ri­men­tal stu­dy will be con­duc­ted, sup­ple­men­ted by the nume­ri­cal model. The results will be appli­ed to indus­tri­al nozz­le sys­tems. Over­all, the project’s objec­ti­ves will be achie­ved through the fol­lo­wing four key are­as of focus.

The modi­fi­ca­ti­on and com­mis­sio­ning of the test rig for the expe­ri­men­tal inves­ti­ga­ti­on of the influence of strip move­ment on heat trans­fer as a func­tion of nozz­le geo­me­try, and the deve­lo­p­ment of a nume­ri­cal model for the exten­ded inves­ti­ga­ti­on of the super­im­po­sed flow cau­sed by strip move­ment and the impinging jet on heat trans­fer. The results are appli­ed to heat trans­fer by deter­mi­ning the local and avera­ge Nusselt num­bers. In the final step, based on the Nusselt num­bers deter­mi­ned for indus­tri­al nozz­le sys­tems, a gui­de is pro­du­ced con­tai­ning empi­ri­cal for­mu­lae for the design of nozz­le sys­tems that take into account the influence of belt movement.