Lagrangian potential flow methods are a promising alternative to mainstream wind turbine aerodynamics tools such as blade element momentum methods and grid-based computation fluid dynamics approaches. Potential flow methods are relatively easy to setup and robust with respect to geometry. With the advent of numerical techniques such as the fast multipole method, potential flow methods can be made computationally fast. Viscous core modelling has led to improvements in accuracy and numerical robustness. A C++ programming library employing Prandtl-Weissinger lifting line wing models and tailorable potential flow wake models has been developed under the name LibAero. The library offers steady-state, periodic, and unsteady flow simulators that can be used interchangeably with wake models. (Periodic and unsteady simulation are still under development and validation.) Wake models are constructed from potential flow elements such as vortex particles, laments, and sheets. Fast multipole method, symmetry modelling, multigrid method, and relaxation iteration are utilized to accelerate the computation of element-by-element interactions. The computational performance is assessed and the numerical results are validated against wind tunnel experimental data from the MEXICO Project and the Tj reborg wind turbine. The results of steady-state simulations with respect to a variety of numerical options and rotor blade designs are presented and conclusions are drawn.