Studies on Secondary Flow Control in a Low Pressure Turbine Cascade for Aero-Engines by a Composite-Type Device

Abstract

This study proposes a new type of flow control device to minimize the secondary flow effects on aerodynamic performance of a high-lift Low-Pressure（LP）turbine cascade for aero-engines. The secondary flow near the end-walls accounts for a large proportion of the losses of the turbine stage, at the same time it causes a significant change in the exit flow angle, which could lead to increase in loss of the subsequent turbine stage. The proposed device is a combination of two different types of secondary flow control devices previously proposed and verified by the present authors, one is a dimple-type device and the other is a localized Gurney Flap（LGF）. This paper describes first the individual secondary flow control mechanism by each device, followed by the detailed investigation on the combination effects of them on the secondary flow. A linear cascade test facility is employed and measurements using a miniature Pitot tube and 5-hole probe are performed along with RANS simulations. As a result, the usefulness of each of the devices is confirmed in terms of loss reduction and exit flow angle control, while the device performance depends on the experimental conditions. It is also revealed that the combination of two types of devices has a great potential for improving the cascade aerodynamic performance.