低压排汽缸气动优化设计

Aerodynamic Optimization on the Low Pressure Exhaust Hood

结合三阶贝齐尔曲线参数化方法、静压恢复系数评价方法、拉丁立方试验设计、三阶响应面近似模型及Hooke-Jeeves直接搜索算法的组合优化策略,基于iSight优化软件平台,建立了排汽缸外导流环优化设计系统。以静压恢复系数最大为目标完成了单独排汽缸优化设计,采用数值求解三维Reynolds-Averaged Navier-Stokes(RANS)方程的方法验证了耦合低压末级和排汽缸结构的排汽缸优化设计系统的有效性。结果表明,基于优化设计系统进行的优化设计,使得排汽缸静压恢复系数相对于初始排汽缸提高了61.1%,排汽缸蜗壳内的静压损失明显减小,从而验证了排汽缸优化设计的有效性和耦合低压末级对排汽缸气动性能分析的必要性。

Combined with three-order Bezier curve parameterization method of exhaust diffuser profile, static pressure recovery coefficient evaluation method, the combinatorial optimization strategy including Latin square design of experiment, three-order response surface approximated model and Hooke-Jeeves optimization method, aerodynamic optimization design of exhaust hood diffuser for steam turbine is established based on the software iSight. Aerodynamic optimization design of exhaust hood is conducted for the maximum of the static pressure recovery coefficient of exhaust hood. The design variables are specified by the exhaust diffuser profile parameterization method. The aerodynamic performance of the optimized exhaust hood and referenced design is numerically calibrated with consideration of the full last stage and rotor tip clearance. The validation of the presented optimization design system of the exhaust hood is demonstrated. The optimization design results show that the static pressure recovery coefficient of the optimized exhaust hood is higher by 61.1 ~ than that of the referenced design with consideration of the upstream last stage influence. The static pressure loss coefficient of the optimized exhaust hood decreases significantly by comparison with the referenced design. The availability of the developed aerodynamic optimization design of the exhaust hood diffuser and necessity of the coupled with the last stage on the aerodynamic performance of the exhaust hood were also validated.