Wing rock is a highly nonlinear phenomenon when the aircraft suffers undesired roll-dominated oscillatory at high angle of attack (AOA). Considering the strong nonlinear and unsteady aerodynamic characteristics, an uncertain multi-input and multi-output (MIMO) nonlinear wing rock model is studied, and system uncertainties, unsteady aerodynamic disturbances and external disturbances are consider...

An unsteady aerodynamics model of a flexible unmanned air vehicle is presented in this paper. The unsteady aerodynamics results from structural vibrations of the flexible airframe which affect the airflow around it. The doublet lattice method, which is a potential flow based panel method, is used for obtaining the basic unsteady aerodynamics model. It gives the pressure distribution on a liftin...

The goal of this work is to develop low-order models for the unsteady aerodynamic forces on a small wing in response to agile maneuvers and gusts. In a previous study, it was shown that Theodorsen’s and Wagner’s unsteady aerodynamic models agree with force data from DNS for pitching and plunging maneuvers of a 2D flat plate at Reynolds numbers between 100 and 300 as long as the reduced frequenc...

3D techniques are increasingly used in aerospace industry to improve quality and performance of aircrafts. This paper presents a 3D imaging technique for studying the aerodynamic shape and flight performance of micro air vehicles. 3D stereoscopic vision, based upon stroboscopic imaging, was utilized to obtain the 3D information of the aircraft’s flexible aerodynamic surface. The aircraft models...

The effect of an increase in speed relative to the speed of sound on the unsteady flow round a harmonically oscillating aerofoil, is to increase the lag of the aerodynamic forces and moments behind the deflection when the frequency is small. It is shown theoretically that this will result in a serious deterioration of the damping of both the lateral oscillation and the high frequency longitudin...

The unsteady aerodynamic forces of a model fruit fly wing in flapping motion were investigated by numerically solving the Navier-Stokes equations. The flapping motion consisted of translation and rotation [the translation velocity (u(t)) varied according to the simple harmonic function (SHF), and the rotation was confined to a short period around stroke reversal]. First, it was shown that for a...

The unsteady-state aerodynamic performance results of various MEMS-fabricated titanium-alloy wing designs are presented. These wing are tested in a high-quality low-speed wind tunnel with velocity uniformity of 0.5%.. For the first time, we have identified the importance of spanwise stiffness effect in generating the leading edge vortices. These vortices, generated around each wing, cause a low...

Low Reynolds number aerodynamics is important for various applications including micro-aerial vehicles, sailplanes, leading edge control devices, high-altitude unmanned vehicles, wind turbines and propellers. These flows are generally characterized by the presence of laminar separation bubbles. These bubbles are generally unsteady and have a significant effect on the overall resulting aerodynam...

The results from two numerical simulations of the unsteady flow in a 1-1/2 stage axial-flow turbine are presented and compared with experimental data to show both the effect of blade count on the solution accuracy and the time-averaged and unsteady flow physics present. The TFLO three-dimensional, multi-block, massively parallel turbomachinery flow solution procedure is used to simulate the flo...