Optimization method for nozzle control of governing turbine

Abstract

The compressed air energy storage (CAES) system necessitates rapid and precise adjustment of turbine operational states to align with fluctuating system loads during the energy release process. As the air storage pressure continuously declines, the adoption of an appropriate air distribution method becomes imperative to enhance turbine performance. This study innovatively investigates the coupled optimal method of nozzle control (NC) and relative stator installation angle (RSIA) to achieve maximum specific work under certain output work conditions, initially proposing the optimal method as a strong candidate for engineering applications. The stator channel has undergone redesign to allow adjustment of the stator installation angle. It is investigated to obtain the response surface model of specific work and output work with base pressure (BP), regulated pressure, inlet nozzle number, and RSIA as independent variables, and the maximum specific work as the optimization objective. The results indicate that, compared with the original NC method at rated output work, the optimized operation markedly elevates the specific work by a maximum of 6.1 % and an average of 3.4 %. Furthermore, the majority of losses within the turbine are attributed to entropy production rate by turbulent dissipation, accounting for up to 88.7 % of the total losses. The optimal method satisfies the output work requirement by adjusting the inlet nozzle number and RSIA without throttling the inlet nozzles under different BP conditions. This is achieved by adopting the 3-nozzle inlet method under high BP and the 4-nozzle inlet method under relatively lower BP conditions. The present study offers theoretical support for the optimal design and operation control of NC turbines, which has broad prospective applications in the optimized air distribution regulation of CAES systems.