On the Development of High-Lift, High-Work Low-Pressure Turbines

Abstract

Here, we describe a combined design, numerical, and experimental program intended substantially to increase the lift and work of low-pressure turbine stages. This exercise is critically dependent upon the appropriate modeling of boundary-layer transition over airfoil surfaces. The effort proceeds through the design of turbine stages consistent with future unmanned air vehicle engine cycles. Then, a series of experiments are described that increase in complexity while driving the technology to more realistic embodiments. Representative experimental data are compared to pre-test predictions of the flow field, and it is shown that acceptable Reynolds-lapse behavior is achievable even for turbines with significantly increased lift and work over state-of-the-art systems. Additionally, it is shown that through the judicious use of appropriate flow control technologies, it is possible to improve further the lapse characteristics of very high-lift airfoils. Finally, the benefits of applying such high-lift, high-work low-pressure turbine components are outlined with respect to a notional aircraft system, and future experiments are proposed.