| In the recent years, the development of Unmanned Aerial Vehicles (UAVs) challenged the design of gas turbine engine. During high altitudes cruise of UAVs, the operation Reynolds numbers for the low pressure turbine (LPT) in an aircraft gas turbine engine can drop below 25000, a condition resulting in laminar boundary layers separation on the blade suction surface. The increased susceptibility of laminar boundary layers to separation can lead to drastically reduced stage efficiency. So, it is necessary to study and explore flow control methods to prevent the boundary layer separation.In this paper, detial numerical investigation was performed to control the flow separation occurred on the suction side of LPT at low Reynolds number condition using Vortex Generator Jets (VGJs). The intent of this research is to reveal in-depth the physical mechanisms of VGJs. It is hoped that this research can provide physical insights into this complex flow as well as establish the theoretical foundation for designing the high-performance gas turbine engine.The numerical simulation results show that flow loss caused by mixing loss and the separation loss can be largely reduced wilh VGJs. The effects of VGJs holes diameter and the holes space were investigated in this paper. Two new configurations of VGJs were put forward and were investigated One is the VGJs with combination of different diameter holes and another is the reversed injection VGJs. Because the effect of the interaction between the jet flow and the free stream is reduced, the combination VGJs could reduce the flow loss apparently with smaller jet flow mass.The analyse of reversed injection VGJs was shown that the VGJs with 180 Degree skew angle and 135 Degree skew angle can be treated as the Turbulence Intencity Generator. This mechanism of controlling the flow separation is very different from the 90 Degree VGJs. It was shown that the reversed injection VGJs may be the best way to reduce the flow loss.
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