Optimized Design And Analysis Of Supercritical Carbon Dioxide Radial Inflow Turbine

The supercritical CO₂?SCO2?Brayton cycle has been receiving an increasing amount of attention due to its advantages,which include high efficiency,compactness,environmentally friendliness,etc.The radial-inflow turbine?RIT?is a key component of the SCO2 Brayton cycle,and its efficiency has a significant impact on the cycle efficiency.Therefore,it is necessary to carry out design research and performance analysis for the SCO2 RIT.In this paper,the design method of the SCO2 RIT is studied,and the influence of the inlet volute and the wheel back cavity on the performance of the SCO2 RIT is analyzed.A one-dimensional optimized design and analysis system for the SCO2 RIT has been established.Based on the one-dimensional design method and the optimization algorithm,the one-dimensional optimized design program and the one-dimensional performance prediction program under off-design condition for SCO2 RIT have been developed in this paper.Besides,the existing loss models of RIT have been selected using the experimental data and CFD supplementary data.Finally,the two SCO2 RITs are designed by the optimized design program.In order to evaluate the calculation accuracy of the loss model and the effectiveness of the optimized design program,the one-dimensional performance predictions have been compared with the numerical simulation results for the optimized RIT and baseline.The comparison results show that the selected loss models have good prediction accuracy for the SCO2 RIT in the whole working condition;compared with the baseline,the performance of the optimized RITs is improved under the most operating conditions for the both SCO2 RITs.The inlet volute of the SCO2 RIT has been designed ans analyzed.In this paper,the coupling calculation for the inlet volute,nozzle and rotor impeller of the SCO2 RIT has been carried out by the numerical simulation method to analyze the influence of the inlet volute on the SCO2 RIT.The loss models of the stator component are checked based on the simulation results.The simulation results show that the aerodynamic performance of the designed inlet volute is good,and its internal flow field does not change with the change of operating conditions;the total pressure loss coefficient of stator component is about 0.133.The numerical simulation has been carried out on the SCO2 RIT with the wheel back cavity.Fousing on the flow characteristics in the wheel back cavity,and the influence of the wheel back cavity on the SCO2 RIT efficiency and axial force with the leakage flow is found.The calculation results show that the leakage flow has a recirculation phenomenon near the suction surface of the impeller blade of the cavity inlet,and the size of the recirculation zone is affected by the pressure difference between the inlet and outlet of the wheel back cavity.As the leakage flow increases,the increase of the loss caused by the wheel back cavity results in the decrease of the turbine efficiency,and the decrease of cavity outlet pressure results in the increase of the volute axial force Overall,the wheel back cavity has a great impact on the performance of the SCO2 RIT.