The fluid dynamics of a microturbine system that is applied in a device for chemical and biological analysis—a so-called magic-angle spinning (MAS) probe—is investigated. The drive fluid is pressurized air at ambient temperature provided by nozzles aligned on an intake spiral, driving a Pelton-type microturbine. Computational fluid dynamics (CFD) simulations have been performed and compared with fluid dynamics measurements of the MAS system with 1.3 mm rotor diameter for spinning rates between 23 kHz and 67 kHz . The main optimization criteria of the MAS system are rotor speed and turbine stability and not primarily efficiency, which is standard for turbomachinery applications. In the frame of fabrication tolerances, a sensitivity study has been carried out by varying the nozzles diameter and the nozzle position relative to the rotor. The presented fluid dynamics study of the microturbine system includes the analysis of local fluid flow values such as velocity, temperature, pressure, and Mach number, as well as global quantities like forces and driven torque acting on the turbine. Comparison with the experimental results shows good agreement of the microturbine efficiency. Furthermore, the parameter study of the nozzle diameter reveals optimization potential for this high-speed microturbine system employing a smaller nozzle diameter.

This paper introduces and experimentally demonstrates the design concept of multistage microturbomachinery, which is fabricated using silicon microfabrication technology. The design process for multistage microscale turbomachinery based on meanline analysis is presented, along with computational fluid dynamics predictions of the key aerodynamic performance parameters required in this design process. This modeling was compared with a microturbine device with a 4 mm diameter rotor and 100 μ m chord blades, based on microelectromechanical system technology, which was spun to 330,000 rpm and produced 0.38 W of mechanical power. Modeling suggests a turbine adiabatic efficiency of 35% and Re = 266 at the maximum speed. The pressure distribution across the blade rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 W with an adiabatic efficiency of 63% at a rotor speed of 1.1 × 10 6 rpm .