Efficiency Variation on a 4-Stage Low Speed Research Compressor With a Redesigned Cantilevered Stator

Numerical simulations with the steady 3D RANS were performed on a 4-stage low speed research compressor (LSRC) with two typical configurations (a shrouded and a redesigned cantilevered stator of the third stator). The shrouded stator (SS) with 0.67% labyrinth seal clearance of the blade height is the prototype, and the cantilevered stator (CS) with 1.2% hub clearance of the blade height is the redesigned cantilevered stator. The fourth rotor that follows after the cantilevered stator was redesigned (RE) according to blade load and inlet flow angle changed based on the redesigned cantilevered stator. The overall performance of the 4-stage LSRC and the distribution of aerodynamic parameters along the blade height were compared between the prototype and the redesigned third stator. Flow characteristics of the third stator and fourth rotor were analyzed in detail. The results indicate that the flow characteristics below the 35% blade height are very different between the prototype and the redesigned due to the effect of leakage flow from seal cavity and hub gap, respectively. The stall margin of CS is 57% higher than SS. The efficiency of CS at the design point is 0.82% higher than SS. Through the redesigned process of R4, the stall margin of RE is 45% higher than CS and the efficiency of R4 is 0.6% higher on average over the entire operating range.