Application of an air-curtain fluidic jet type seal to reduce turbine shroud leakage.

This paper describes the design and optimization of an ‘air-curtain’ type seal using a fluidic jet to reduce tip leakage losses on a small high-speed single stage axial turbine device. The application will essentially demonstrate proof of concept for turbomachinery applications, opening the door for the development of future designs for applications in all scales of turbomachine. CFD is used to develop and optimize the seal design. The performance benefit from applying the new seal is predicted. These calculations illustrate the importance of accurately accounting for the effects of the sealing jet on shroud shear forces, in addition to leakage flow reduction, when determining the overall gain in turbine output power from the improved sealing. It is planned to validate the new seal design in full-scale turbine tests, during the next phase of the work