Research on One-dimensional Coupling Design of Axial Turbine and Diffuser Section of Exhaust Casing
In order to explore the one-dimensional design variable selection law of the axial turbine cou-pled exhaust casing diffuser section,and improve the performance of the exhaust casing diffuser section,referring to the existing NRCC cascade guide vane model,a one-dimensional design model of the coupling of axial turbine and exhaust diffuser section was constructed by using self-programmed program and theo-retical analysis.The factors affecting the static pressure recovery coefficient and overall performance of the diffuser section in the coupling design were analyzed in detail.The results show that the area ratio,average inclination angle,divergence angle and wall friction coefficient in the design parameters of the diffuser section not only affect the static pressure recovery coefficient of the diffuser section,but also af-fect the aerodynamic efficiency of the turbine;for the research model in this paper,the overall perform-ance is best when the area ratio is 3.5,the average inclination angle is 30°,and the divergence angle is 5°;however,the Mach number,blade tip leakage flow and outlet swirl of the turbine outlet gas flow have a great influence on the performance of the diffuser section,and the increase of the outlet radius ratio re-duces the static pressure recovery coefficient,so the selection of the above parameters of the turbine should be fully considered when coupling the design.
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