Study On Flow And Heat Transfer Characteristics Of Rotational Cross-Rib Cooling Channel

Cross-rib cooling channel is an important kind of turbine blade internal cooling structure,cross-rib structure is more complex than the general cooling structure,the flow and heat transfer characteristics are completely different from the traditional column rib cooling chan-nel and rib cooling channel.When the cross-rib for blade internal cooling,the whole flow field in rotating state,the flow characteristics is more complicated than static,the differences between static and rotating flow condition will inevitably lead to differences in heat transfer,research on characteristics of cross-rib cooling channel under rotational condition is necessary.In this paper,the flow and heat transfer characteristics were studied by using commercial software CFX.The following main tasks were carried out:1.The grid independent test and the choice of turbulence model were carried out.The three-dimensional model of the cross-rib cooling channel was established by using the 3D modeling software UG.The size of the experimental section was consistent with that in the reference.The model was meshed with ICEM software and verified by grid independence.Seven different turbulence models were calculated,the data in each turbulence model was compared with the experimental data in the reference and the most suitable turbulence model was selected.2.The flow field data of cross-rib under different Rotation numbers and Rotation direc-tion angles was analyzed.When analyzing of Rotation number on the flow effect,Rotation number from 0 to 0.8,the distribution of the Coriolis force and the influence of the Coriolis force on the mass exchange and velocity of the upper and lower channels were analyzed.The data show that the role of Coriolis force changes the upper and lower channel mass exchange rules so that the upper channel impact to be stronger and the near-wall velocity increasing,the lower channel flow impact weakened and near wall velocity decreasing.The total pressure loss is an important index for evaluating the cooling structure,the total pressure loss charac-teristics under different Rotation number,Reynolds number and Rotation direction were cal-culated.The total pressure loss increases with the grow of Rotation number,decreases with the grow of Reynolds number.And the effect of Rotation number on the total loss of the crossed-rib is much greater than the influence of the Rotation direction on the total pressure loss.3.The cross-rib heat transfer data under different Rotation numbers,Reynolds numbers and Rotation direction angles was analyzed.The heat transfer characteristics under constant heat flux density also studied.Cross-rib surface is an important part of heat transfer.Accord-ing to the relative position of the cross-rib in the turbine blades the surface was divided into suction surface and pressure surface which is equivalent to the suction surface and pressure surface of the turbine blade.It is found that the heat transfer of the suction surface increase when Rotation number growing and the heat transfer of the pressure surface decrease.But the grow of the Reynolds number increases the heat transfer of suction surface and pressure sur-face.The influence of Rotation number on cross-rib heat transfer is much greater than that of Rotation direction on it.In this paper the constant heat flux boundary was studied in addition to the boundary of constant temperature and the heat transfer between the suction surface and the pressure surface decreases with the grow of the Rotation number.