Modal decomposition techniques, flow field, and spectral analysis are employed to investigate the wake dynamics destabilization mechanisms of a four-bladed marine propeller with or without nozzle. Numerical simulations conducted using delayed detached eddy simulation model for arbitrary mesh interface method blade rotation. The presence nozzle significantly reduces wake's streamwise velocity, d...

.................................................................................................................................. 1 TABLE OF CONTENTS .............................................................................................................. 2 INTRODUCTION ...........................................................................................................................

This contribution describes the usage of the ducted fan as a possible actuator of a multicopter vehicle. The measurements are focused on both dependence of forward thrust on current consumption and on dependence of forward thrust on RPM. The measurement results of the ducted fan are compared with the measurement results of a regular propeller. The dependence of actual efficiency on static thrus...

Model predictive control (MPC) is applied to the Caltech ducted fan, a thrust-vectored flight experiment. A real-time trajectory generation software based on spline theory and sequential quadratic programming is used to implement the MPC controllers. Timing issues related to the computation and implementation of repeatedly updated optimal trajectories are discussed. Results show computational s...

The morphology of ELF hiss events observed at low-latitude ground station Varanasi (L = 1.07, geomagnetic latitude 14°55¢N) are reported, which consist of two types: (1) events which propagated in ducted mode along the geomagnetic ®eld line corresponding to observing station Varanasi and (2) events which propagated in ducted mode along higher L-values (L = 4±6), after reaching the lower edge of...

MIT is developing an Earth-based hopper prototype for autonomous planetary exploration. This paper describes the initial development of the hopper prototype and its application as a testbed for lunar hopper technologies. The prototype hopper consists of a gravity-canceling system, composed of battery-powered electric ducted fans, and an integrated lunar hopper system, which operates using cold ...

Sway reduction is very vital in a nonlinear oscillatory system such as a gantry crane. In this paper, a new design is proposed for active sway control of a gantry crane using an electrical ducted fan. The thrust force developed by the motor is used to cancel out payload oscillation. A dynamic model of the crane with a ducted fan is derived and simulated using Matlab. Performance of the proposed...

Ducted gravity waves are associated with potentially large perturbations in horizontal winds. It may be shown, neglecting friction, that these perturbations are maximized at the surface and minimized at the top of the wave duct, producing perturbation vertical wind shear as well. The magnitude of this shear is maximized in the wave ridge and the wave trough. The perturbation shear may be signif...