Study on flow and heat transfer characteristics of two axial preswirl structures

Abstract

Turbine blade cooling air is facilitated in part by the pre-swirl system, a crucial part of the aero-engine secondary air system. This article primarily focuses on the pre-swirl angle and the turbine co-rotating cavity in order to improve the pre-swirl system's temperature drop. It also employs the thermochromic liquid crystal test method to investigate the pre-swirl system's temperature drop characteristics and the cavity's cooling effect. The experimental parameters are measured at different flow rates when the rotational Reynolds number is between 2.97 × 10⁶ and 4.23 × 10⁶. The results indicate that within the experimental operating range, for the axial pre-swirl structure, the fluid velocity is fast and the static temperature is significantly reduced after pre-rotation. The higher the rotational Reynolds number, the lower the static temperature of the fluid passing through the receiving hole, and the higher the outlet temperature rise. The tangential velocity of the 15-degree preswirl structure is low, the static temperature of the receiving hole is high, and the average outlet temperature increases. In terms of pressure loss, the higher the rotational Reynolds number, the lower the fluid static pressure. The larger the pre-swirl flow rate, the higher the static pressure inside the cavity. The outlet static pressure of the 15-degree structure is higher than that of the 10-degree structure. The swirl ratio increases with an increasing flow rate. The swirl ratio decreases as the rotational Reynolds number increases. The 15-degree structure's swirl ratio is significantly lower than that of the 10-degree structure. Entropy generation is mostly produced along the trailing edge of the blade and in the vicinity of the wall, and the entropy generation of the 15-degree preswirl structure is higher than that of the 10-degree structure. On the disc's surface, the convective heat transfer coefficient rises with a rising dimensionless flow rate and falls with an increasing rotational Reynolds number.