Patent ID: 8527247

Claim:
A method of determining pitch stability characteristics of an airfoil, comprising using a computer to numerically integrate a differential equation of motion characterizing a time-dependent response of an airfoil's pitch angle, α, measured relative to direction of an incoming fluid flowing towards the airfoil; wherein the method comprises steps of: a) inputting airfoil design parameters and system initial conditions to a memory unit of a computer; b) programming into the memory unit a differential equation of motion that models a response of the airfoil's pitch angle as a function of time; c) the computer calculating the time-dependent response of the airfoil's pitch angle, energy generation (E gen ), and energy dissipation (E diss ), by using a microprocessor in the computer to numerically integrate the differential equation of motion over a specified period of time; d) storing results of the numerical integration step in the computer's memory, wherein the results comprise: α, E gen , and E diss as a function of time; e) inspecting the results, and then categorizing an airfoil's transient response as being: (1) Passive if the response is damped and dissipative, (2) Neutral Limit-Cycle if the response is balanced and stable, or (3) Unstable if the response is generative and divergent.