Flow controlling on low pressure turbine using passive methods

Abstract

Flow control in low pressure turbine using passive devices is efficient technique to raise the efficiency of engine. In this study T106A LP Turbine geometry is used for controlling the flow separation using passive device. A lot of work is done for flow controlling using different kind of passive devices like dimples, bumps, riblets etc. Work on the backward step geometry for controlling the flow separation is not done effectively. Fine structured mesh is created with boundary layer (y + <; 1) an unstructured meshing in the rest of the domain. Unsteady RANS are solved using the Gamma-Theta Model Transitional Model for capturing the laminar separation bubble. In this study a smooth backward step of different height to length ratios (h/1) are applied on the 65% axial chord length for the reduction of loss coefficient which is another way to specify the efficiency of turbine using pressure values. After specifying the best h/1 ratio at 65% axial chord where the losses are minimum, this specific h/1 ratio step is shifted at different axial locations to And out the optimal location where the maximum losses are reduced. By making the coefficient of pressure plots and boundary layer profiles, it has been confirmed that backward step completely control the laminar separation bubble and also reduce the loss coefficient.