Yasunori Sakuma

Numerical Analysis of Flow in a Transonic Compressor With a Single Circumferential Casing Groove: Influence of Groove Location and Depth on Flow Instability

The effect of circumferential single grooved casing treatment on the stability enhancement of NASA Rotor 37 has been examined with computational fluid dynamics analysis. Stall inception mechanism of Rotor 37 is presented first with principal focus on the tip leakage flow behavior, passage blockage, and the vortical flow structures. Detailed observation showed that the combined interaction of the stagnated flow of tip leakage vortex breakdown and the jetlike leakage flow from the midchord region leads to the blade tip-initiated stall inception. The result of numerical parametric study is then demonstrated to show the effect of varying the axial location and the depth of a circumferential single groove. The evaluation based on stall margin improvement showed a higher potential of deeper grooves in stability enhancement, and the optimal position for the groove to be located was indicated to exist near the leading edge of the blade.

Numerical Analysis of Flow in a Transonic Compressor With a Single Circumferential Casing Groove: Application to Two Different Compressor Rotors

The effect of a single circumferential casing groove on the stability enhancement of two different transonic compressors has been examined with CFD analysis. The differences in flow field and stall inception mechanism between two rotors are presented with principal focus on passage blockage and tip leakage flow behavior. Detailed observation showed that the blockage flow which leads the compressor to stall was different between each other. A parametric study conducted with respect to the axial location of the groove has clarified that the effect which groove has on the tip leakage flow behavior changes according to the blade tip loading and the design tip clearance gap at the location where the groove is applied. When the casing treatment was applied to the compressors with different instability mechanism, whether the casing treatment could enhance the stability of compressor or not was not only dependant on the extent of the influence which it had on the flow field but also on whether it could affect the original stall-initiating phenomena at the adequate location.Copyright