Numerical Study Of Air Cooled Turbine Blade With Crossed-rib Structure

Turbine blade cooling plays a crucial role in improving turbine inlet gas temperature,power and efficiency of gas turbine.And the crossed-ribs channel is drawing more and more attention for its strong effect of cooling.The work of this paper is using commercial software CFX to numerically investigate cross rib structure used in a turbine blade as well as the integrated turbine blade.Conjugate heat transfer method is used to get an accurate blade temperature distribution with unstructured tetrahedral meshes.This paper numerically investigated the influence of rib width,the incline angle β of ribs and rib spacing upon the flow and heat transfer characteristics by eleven different models under five different conditions.The calculation results show that the average Nusselt number and flow resistance coefficient of channel were increased with increasing rib width and decreased with increasing the rib spacing;The channels with the rib incline angle of 15° has a better comprehensive effect.The influence of positive and negative gaps on the heat transfer and flow resistance characteristics of the cross rib channel between two layers of ribs is studied.The results show that when there is a negative gap layer between the fins,the average Nusselt number increased slightly,the flow resistance coefficient increases,the comprehensive heat transfer effect is greatly reduced;The positive gap between the upper and lower channels has a great influence on the heat transfer of the channel,the larger the gap value,the worse the average Nusselt number,the smaller the flow resistance coefficient,the better the comprehensive heat transfer effect.In addition,the numerical simulation as the data sets for the prediction of neural network data and numerical simulation results and experimental data in the reference,detailed analysis and forecast the gas cooling efficiency of cross rib cooling channel in the approximate size of different fin geometric parameters values.Finally,a numerical simulation study on the turbine blade with compound cross rib internal cooling structure is carried out by means of fluid solid heat transfer coupling method.By changing the geometrical parameters of the 45 degree cross ribs and the arrangement of the upper and lower ribs,the simulation models of the different internal cooling structures are obtained.And the effects of different rib width,fin spacing and fin arrangement on the flow and heat transfer characteristics are analyzed in detail.The results show that the blade surface temperature distribution is more uniform when the composite cross rib cooling structure is adopted;When there is no gap between the upper and lower ribs,the surface temperature distribution is almost the same;When the internal composite cross rib cooling blade side there is gap or reduce the pressure surface of the composite cross rib rib number,not only better cooling effect,and can greatly reduce the processing difficulty and manufacturing cost of the blade.Through the comparative study of different cooling schemes,advantages and disadvantages of cooling structure used in low pressure turbine blade were analyzed which indicated a optimization direction on cooling structure.