Challenges in Aerodynamic Performance of Micro Gas Turbines and Design Inefficiencies

Abstract Micro Gas Turbines (MGTs) hold significant potential for applications in distributed power generation, aviation, and military sectors due to their compact size and high power density. However, their performance is hindered by substantial aerodynamic challenges, including inherently low Reynolds number flows, large tip clearances, thick trailing edges, and low aspect ratios, all of which contribute to increased aerodynamic losses. To investigate these challenges, this study employs Large-Eddy (LES) with Reynolds-Averaged Navier-Stokes (RANS) methodologies on a single-stage Wren100 turbine (capable of 100 N thrust and ∼20kW power), focusing on critical design aspects such as stator and rotor Reynolds number of around 30,000 to 60,000. The research begins with baseline LES analyses to capture unsteady flow structures, laminar separation, and tip leakage effects. Parametric redesigns of stator vane count, aspect ratio (AR), trailing edge thickness, and rotor tip clearance are then proposed to address identified loss sources. Results demonstrate a thrust increase from 24.25N to 29.95N and a rise in rotor isentropic efficiency from 80.1% to 81.1% by optimising stator parameters. Further reducing rotor tip clearance from 5% to 2.5% of blade height improves efficiency to 83.4% while sustaining the improved thrust levels. Although aerodynamic challenges remain, targeted geometry refinements can yield tangible performance gains, offering guidance for next-generation MGT development that balances efficiency with manufacturability. Future work will focus on experimental testing of these redesigned components, along with optimisation methods that incorporate thermal and structural constraints to further refine MGT performance.