Imomlbressibte Flow Summary.-The report presents the theoretical calculations of gust alleviation factor made for rigid aircraft and with one degree of freedom only (i.e., vertical motion). It is shown that for average gust lengths and for orthodox (tailed) aircraft the influence of thesecond degree of freedom (i.e., pitching) on the value of the gust alleviation factor is negligibly small, pro...

This paper discusses energy extraction from atmospheric turbulence by smalland microuninhabited aerial vehicles. A controller which superimposes a gust-dependent control input on a state-feedback derived control input is proposed, and a genetic algorithm is used to obtain control gains as well as the optimal nominal trim state is described. Control laws are designed for both vertical sinusoidal...

The unsteady motion of thin, slender wings with leading-edge vortioes is considered. Incompressible flow and slender-wing theory are assumed throughout , and use is made of an analogy between the unsteady flow and related steady flows. The particular motions treated are: (i) a sudden plunging motion, or change of incidence, (ii) entry into a gust, For the first case, it is shown that the flow i...

Experimental results of sharp edge potentials in the quantum Hall (QH) regime of a two-dimensional electron system are presented. First the general QH edge state picture is reviewed, including recent theory which explains the importance of incompressible strips at the sample edge. Then two sharp edge geometries are presented where incompressible strips are predicted to vanish below the scale of...

The objective of this paper is the implementation and validation of an adaptive controller for aircraft gust load alleviation. The contribution of this paper is the design of a robust controller that guarantees the reduction of the gust loads, even when the nominal conditions change. Some preliminary results are presented, considering the symmetric aileron deflection as control device. The prop...

Anomalous acoustic streaming is observed emanating from sharp edges of solid bodies that are vibrating in fluids. The streaming velocities can be orders of magnitude higher than expected from the Rayleigh streaming at similar amplitudes of vibration. Acoustic velocity of fluid relative to a solid body diverges at a sharp edge, giving rise to a localized time-independent body force acting on the...

Future hypersonic vehicles are likely to use sharp leading edges on wings and engine inlets to reduce drag. The radius of curvature associated with such structures may be one centimeter or less. The very small size leads to high heating rates that can be accommodated using advanced materials. An additional aspect of the small size concerns the basic gas dynamics. At such small scales, the conti...

In many cases, a set of obstacles, such as bridge piers and abutments, are located in the river waterway. Bridge piers disrupt river’s normal flow, and the created turbulence and disturbance causes diversion of flow lines and creates rotational flow. Geometric shape and position of the piers with respect to flow direction and also number of piers and their spacing are effective on changing the ...