Unsteady aerodynamics analysis for small amplitude pitch oscillations of transonic cruiser aircraft

The behavior of the aircraft under oscillations in pitch, roll, yaw and plunge during the flight are crucial for the development of flight control systems and in determining the flight envelope of the aircraft. At present, the prediction of dynamic behavior of the aircrafts are mainly carried out using flight tests. These analysis at the last stage of aircraft development leaves least opportunities to make design changes and are expensive and time consuming. Till date Computational Fluid Dynamics (CFD) is not effectively used in this field due to the huge computational requirements to carry out the required studies and due to the lack of maturity of numerical tools to predict the involved unsteady flow features like highly separated flows. With availability of advance computing capabilities and maturity of CFD solvers, authors have put efforts to use full RANS simulations in carrying out the unsteady forced dynamic motion of the aircraft and compared it with the experimental data. And efforts are put to evaluate the flow physics predicted by CFD. This research paper presents CFD validation of low-speed small amplitude pitch oscillations test data for a Transonic Cruiser (TCR) Aircraft using Metacomp's CFD++ solver. The Stiffness and Damping of the Normal Force and Pitching Moment, estimated by Linear Regression Analysis (Least Squares) are in good agreement with the experimental data even in high angle of attacks.