Evaluation of Dynamic Derivatives Using Computational Fluid Dynamics

TLDR

The paper evaluates the dynamic stability derivative formulation. The study validates dynamic derivative predictions using two test cases, assessing their ability to predict large‑amplitude motion forces and moments. Derivatives are computed with Euler and RANS equations using a time‑domain solver, and dynamic simulations for standard and transonic cruiser geometries were performed to validate static and unsteady aerodynamic characteristics. The dynamic derivative model shows satisfactory agreement with experiments and captures parameter dependencies, but it fails to represent all important aerodynamic effects, limiting its predictive capability for large‑amplitude motions.

Abstract

This paper focuses on the evaluation of the dynamic stability derivative formulation. The derivatives are calculated using the Euler and Reynolds-averaged Navier–Stokes equations, and a time-domain solver was used for the computation of aerodynamic loads for forced periodic motions. To validate the predictions, two test cases are used. For the standard dynamic model geometry, a database of dynamic simulations illustrates the effects of the systematic variation of motion and fluid parameters involved. A satisfactory agreement was observed with available experimental data, and the dependency of dynamic derivatives on a number of parameters, such as Mach number, mean angle of attack, frequency, and amplitude, was assessed. For the transonic cruiser wind-tunnel geometry, static and unsteady aerodynamic characteristics were validated against experimental measurements. The ability of models based on the dynamic derivatives to predict large-amplitude motion forces and moments was assessed. It was demonstrated that the dynamic derivative model does not represent all of the important effects due to aerodynamics.