Gas-dynamic analysis of the bandage seal of an LPI impeller manufactured by SLS printing

Abstract

The development of additive technologies and polymer materials opens up new applications in mechanical engineering, particularly in turbine engineering. For instance, studies have already demonstrated the potential of using polyamide parts manufactured by SLS printing for low-flow turbine stages, with experimental investigations confirming their effectiveness. This manufacturing method allows the consideration of new shapes for elements of the flow part of gas turbines that cannot be produced by mechanical machining of workpieces. This article discusses a radial centripetal impeller of Leningrad Polytechnic University design, intended for use in an autonomous turbogenerator in a gas distribution line. This impeller features an adapted bandage seal designed to accommodate the specific requirements of SLS printing manufacture. The aim of this work is to demonstrate the effectiveness of the proposed seal design through a gas dynamic analysis of three stage variants: without a seal, with a bandage seal, and with a counter labyrinth on the stator. The calculation was performed at the design parameters, accounting for the circumferential periodicity of the stage in the Ansys CFX software package during the combined operation of the nozzle assembly and the impeller. The final comparison is made by calculating the adiabatic efficiency, determined from the power generated on the impeller (via torque) and the available power. Analysis of the results showed the positive effect of using this seal, especially for the variant with reciprocal labyrinth channels, indicating the feasibility of introducing this design into such machines and the need for further work to optimize the seal in terms of both gas-dynamic and strength properties.