A New Alternative for Reduction in Secondary Flows in Low Pressure Turbines

This paper describes a new flow mechanism for the reduction in secondary flows in low pressure turbines using the benefit of contoured endwalls. The extensive application of contoured endwalls in recent years has provided a deeper understanding of the physical phenomenon that governs the reduction in secondary flows. Based on this understanding, the endwall geometry of a linear cascade of solid-thin profiles typical of low pressure turbines has been redesigned. Experimental data are presented for the validation of this new solution. Based on these data, a reduction of 72% in the secondary kinetic energy helicity (SKEH) and 20% in the mixed-out endwall losses can be obtained. Computational fluid dynamics simulations are also presented to illustrate the effect of the new endwall on the secondary flows. Furthermore, an explanation of the flow mechanism that governs the reduction in the SKEH, and the losses is given.