Modelling and simulation of a fluid-driven microturbine

In this paper, an analytical study is presented which looks at the interaction between a rotor and shaft structure and surrounding viscous flow in steady state for a proposed microturbine. The finite element analysis (FEA) package, ANSYS, has been used for analysing in 3D, a nonlinear behaviour model of the fluid-structure interaction. The microturbine module consists of cavity, rotor, step and shaft with air applied as the driving fluid. The rotor can be fixed rigidly on to the shaft, where the shaft itself is free to move up or down but the rotor can also be considered to be rotating around a fixed shaft. Displacement and deflection of the rotor can be derived by the simulation model from the consideration of fluid pressure applied to the inlet at typically 2 kPa. Results are presented for levitation, torque and the volume of gas escaping from small gaps at the top and bottom of the unit, with the shaft protruding out of the module. This is the first step towards considering the power output from the turbine, since this would be done by attaching some sort of gearing mechanism to the protruding shaft.