Effect of nozzle profile on the performance of nozzle governing radial turbine

For the compressed air energy storage (CAES) system, the air storage pressure changes continuously throughout its operation. It is important to adopt an appropriate air distribution method for the turbine to ensure its efficient operation. In this study, the response surface-assisted Sobol sensitivity analysis method is used to find the nozzle profile parameters that have pronounced effects on nozzle governing (NG) turbine performance. The influence of nozzle profiles on flow fields and loss characteristics is also analyzed. The total throat area and the wedge angle of the pressure surface are the nozzle profile parameters that have more influential impacts on the performance of the turbine. The NG turbine performance is markedly affected by the throttling loss, and the internal loss of the turbine with different nozzle profiles exhibits pronounced differences at high base pressure. A non-axisymmetric nozzle stator design method is proposed to improve the specific work. At the base pressure of 10 MPa, when both are regulated using the NG method, the turbine with the selected nozzle profile exhibits a 6.8% increase in specific work compared to the original turbine.