| The increasing power and efficiency of gas turbines has led to an increase in turbine inlet temperatures.The development of turbine cooling technology plays a crucial role in improving the thermal efficiency and power output of gas turbines.Turbine blades have a harsh working environment and are subject to strong centrifugal force,high thermal stress and strong aerodynamic bending and torsion stress.The cooling effect and strength of the blade are the main concerns.In view of the above problems,this paper develops the design and optimization of the internal cooling matrix structure of turbine blades and the study of flow and heat transfer characteristics on it.Firstly,in this paper,the blade is divided into three main areas: the leading edge of the blade,the middle of the blade and the trailing edge of the blade,and the geometric parameters of the matrix structure are obtained from the actual blade modeling.These parameters are used to determine the geometric parameters of molded matrix structure in different regions.The CFX is used to simulate the matrix structure of different rib angles,different rib widths and different rib spacings to study their flow and heat transfer characteristics.Finally,the 1stOpt software is used to fit the empirical formulas of geometric parameters and flow parameters to the average Nusselt number and flow resistance coefficient of the matrix structure in different regions,the estimated value is compared with the actual value,and the error is very small.The design of the modeled matrix structure is used to guide the design of the actual turbine blade matrix structure.The geometrical parameters of the modeled matrix structure of the relevant regions are extracted and applied to the design of the actual turbine blade matrix structure.The blade internal cooling channel is designed as three sets of entire matrix structure with different parameters.The conjugate heat transfer calculation of the entire matrix structure blade model was carried out by CFX.It was found that there was a local over-temperature zone at the leading edge and tip of the matrix structure blade.Therefore,the optimization of the front and the tip of the matrix structure blade is carried out twice,and the conjugate heat transfer calculation is carried out again.The calculation results show that the surface of the blade is not overheated under six different working conditions and meets the allowable temperature requirements of the material.Finally,the matrix structure blade is designed as follows: the rear part of the blade is designed as three sets of matrix structure,the leading edge of pressure surface and suction surface are each arranged with 1 row film hole,and the top of the blade is designed with 8 outflow holes,nine outflow holes are arranged near the top of the pressure surface,a total of 14 non-uniformly arranged impingement cooling holes are arranged between the first set of matrix cooling channel and the leading edge cavity.When the maximum surface temperature of the designed turbine blade meets the allowable temperature of the material,this paper uses the Workbench platform Static Structural module to interpolate the surface temperature and pressure calculated by the conjugate heat transfer to the corresponding blade model,and apply the centrifugal load then perform the intensity analysis.The calculation results show that the original design equal wall thickness matrix structure blade have local stress concentration.In view of the stress concentration phenomenon,this paper develops a low stress design,optimization based on original model,the variable wall thickness matrix structure blade is proposed,and recalculate the strength.The calculation results show that the local stress is reduced in the same area obviously,and the equivalent stress of the blade is within the allowable stress of the material.The safety factor of most of the blade is more than 1.2,and only a small part is above 1.07,which meets the design requirements. |
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