Numerical Study Of Turbine Cascade And Typical Internal Cooling Channels Based On OpenFOAM

Gas turbine is an integral part of economic sustainable development,with high efficiency and high stability advantages.Increasing the turbine inlet temperature is one of the important methods of achieving higher gas turbine cycle efficiency.However,the too high inlet temperature makes the stator and rotor blades and other parts of high pressure turbine suffering from the too high thermal load,even more than the allowable range of materials,so how to design the blade cooling system is particularly important.In a variety of cooling methods,the method of enhancing the cooling through the turbulence generator inside the blade has proven to be effective and convenient.In recent years,numerical simulation has become an effective method to study the internal cooling flow of turbine blades,and large eddy numerical simulation(LES)is becoming more and more widely used.In this paper,some algorithms are improved in open source software of OpenFOAM based on the rhoPimpleFoam solver,and then discusses the application of various turbulence models,including RANS turbulence model,LES One Eqddy subgrid model,DynOneEqEddy subgrid model and so on.In order to save computational resources in the large eddy numerical simulation process,the parallel acceleration in OpenFOAM has been studied.The computational platform is proved to be well compiled by typical viscous cavity flow.The improved numerical algorithm is applied to the simulation of 2D backward facing step and and 3D turbine cascade flow field,then the algorithm is has been verified.It is pointed out that the vortex structure after the step with hyperbolic tangent inlet condition is the most consistent with the experimental results.The results with the turbulent Inlet and fixedValue inlet condition in OpenFOAM are in good agreement,but,the difference with the experimental results is distinct.The comparison of the static pressure and the flow field structure of the 3D cascade shows that the results obtained by the k?-sst turbulence model are in good agreement with the experimental data.The flow mechanism of the ribbed double channel has been studied.It is pointed out that all kinds of turbulence models can simulate the basic law of channel wall heat transfer,but the the results of LES can clearly capture the fine structure of the strong shear effect and reveal the Reynolds stress distribution law.The LES OneEqddy subgrid model is used to study the ribbed dual channel in different rotation directions.The secondary flow induced by Coriolis force during rotation plays an important role in the momentum transport near the wall,and the rotation affects the flow separation?reattached and vortex structure induced by the presence of the ribs.The effects of different rotational directions on the pressure in the channel are similar: the pressure in the radial outflow channel increases as the flow increases,reaching the maximum at the elbow,and then the pressure gradually decreases.Compared with the stationary state:In general,rotation enhances the heat transfer performance on the wall.The ratio of Nusselt number in wall of radial outflow and the radial inward-flow channel increased by 22.72%,35.37%,when anticlockwise rotation,respectively,and increased by 31.18%,15.62%,when clockwise rotation,respectively.The development trend of heat transfer performance on the wall is the same as that of the theoretical analysis under the two rotational states.