TuPraS: Development of a simulation method for turbulence modelling of impinging flows

Impinge­ment jet nozz­le sys­tems are used for hea­ting and coo­ling in con­ti­nuous strip lines for the heat tre­at­ment of steel, alu­mi­ni­um and cop­per strips. Impinge­ment jet nozz­le sys­tems are also used in con­ti­nuous fur­naces for flat glass and in dry­ing sys­tems for paper and tex­ti­les. The nozz­le sys­tems, con­sis­ting of round or slot nozz­les, are direc­ted spe­ci­fi­cal­ly at the strip or mate­ri­al and gene­ra­te an impinge­ment flow that ensu­res high and as homo­ge­neous as pos­si­ble heat transfer.

When the jet impinges on the strip sur­face, a com­plex flow struc­tu­re is crea­ted, which is divi­ded into a free jet, a sta­gna­ti­on zone and a wall jet. The­se high­ly varia­ble flow con­di­ti­ons lead to local­ly very dif­fe­rent heat trans­fers. The nume­ri­cal model­ling of such impinge­ment flows is a major chall­enge, as exis­ting tur­bu­lence models can only relia­bly repre­sent parts of the flow. A con­sis­tent, pre­cise simu­la­ti­on of all rele­vant flow and heat trans­fer phe­no­me­na using sta­tio­na­ry RANS simu­la­ti­ons is not yet possible.

The aim of the pro­ject is to deve­lop a robust and prac­ti­cal simu­la­ti­on method and asso­cia­ted fur­ther deve­lo­p­ments of con­ven­tio­nal tur­bu­lence models to increase the nume­ri­cal accu­ra­cy and pre­dic­ti­ve capa­bi­li­ty of ste­ady-sta­te RANS simu­la­ti­ons for impinge­ment jet flows. Through the increased use of pre­cise nume­ri­cal simu­la­ti­ons, nozz­le geo­me­tries and ope­ra­ting para­me­ters are to be spe­ci­fi­cal­ly opti­mi­sed in the future in order to achie­ve hig­her and more uni­form heat trans­fer while redu­cing ener­gy consumption.

More effi­ci­ent nozz­le sys­tems enable grea­ter pro­cess sta­bi­li­ty, redu­ce ope­ra­ting cos­ts and expand the ran­ge of appli­ca­ti­ons for gas coo­ling in ther­mal pro­ces­sing plants. In many appli­ca­ti­ons, this eli­mi­na­tes the need for more com­plex coo­ling methods such as water or mist coo­ling. This is par­ti­cu­lar­ly important for the manu­fac­tu­re of modern, high-strength steel and alu­mi­ni­um pro­ducts. Sin­ce impact jets are used not only in metall­ur­gi­cal pro­ces­ses but also in the glass indus­try and paper and tex­ti­le pro­ces­sing, opti­mi­sed, nume­ri­cal­ly based design methods offer gre­at poten­ti­al for ener­gy savings, sus­tainable pro­duc­tion and long-term com­pe­ti­ti­ve­ness across the men­tio­ned industries.

The cor­re­spon­ding adjus­t­ments to the tur­bu­lence models are being deve­lo­ped in col­la­bo­ra­ti­on with Merk­le CAE Solu­ti­ons. At the Depart­ment for Indus­tri­al Fur­naces and Heat Engi­nee­ring (IOB), vali­da­ti­on mea­su­re­ments are being car­ri­ed out with sel­ec­ted indus­try-ori­en­ted nozz­le sys­tems, which are used to veri­fy the adapt­ed tur­bu­lence models for indus­tri­al application.