Current Issue : July - September Volume : 2017 Issue Number : 3 Articles : 5 Articles
This research describes a computational study undertaken to determine the effect of a flow control mechanism and its associated\naerodynamics for a finned projectile. The flow control system consists of small microflaps located between the rear fins of\nthe projectile. These small microflaps alter the flow field in the aft finned region of the projectile, create asymmetric pressure\ndistributions, and thus produce aerodynamic control forces and moments. A number of different geometric parameters, microflap\nlocations, and the number of microflaps were varied in an attempt tomaximize the control authority generated by the flaps. Steadystate\nNavier-Stokes computations were performed to obtain the control aerodynamic forces and moments associated with the\nmicroflaps. These results were used to optimize the control authority at a supersonic speed,...
A new annular lift fan configuration that has very high lift efficiency is explored by using\na numerical scheme. The inlet lip radius and diffuser angle are maximized by semicircle duct\nwalls and the location of the lift fan is moved from the throat to the diffuser area to maximize the\ndiffusion effect of the ducted fan. The improved lift fan achieves the figure of merit of 0.772 and the\npower loading of 9.03 lbs/hp without ground effect, very close to the theoretical limit. Under the\nground effect, the figure of merit reaches 0.822 with the power loading of 9.62 lbs/hp. The improved\nlift efficiency deteriorates the transition characteristics with higher momentum drag and pitching\nmoment. However, with the aid of jet thrusts directly providing part of the lift during transition,\nthe peak of momentum drag and pitching moment can be lowered. A total thrust to weight ratio of\n0.7 is enough for all of the requirements in transition and in hover and for the maximum speed of\n0.75 Mach in cruise flight....
Aeroelastic tailoring of laminated composite structure demands relatively high computational time especially for dynamic problem.\nThis paper presents an efficientmethod for aeroelastic dynamic response analysis with significantly reduced computational time. In\nthis method, a relationship is established between the maximum aeroelastic response and quasi-steady deflection of a wing subject\nto a dynamic loading. Based on this relationship, the time consuming dynamic response can be approximated by a quasi-steady\ndeflection analysis in a large proportion of the optimization process. This method has been applied to the aeroelastic tailoring of a\ncomposite wing of a tailless aircraft for minimum gust response.The results have shown that 20%ââ?¬â??36% gust response reduction has\nbeen achieved for this case. The computational time of the optimization process has been reduced by 90% at the cost of accuracy\nreduction of 2âË?¼4% comparing with the traditional dynamic response analysis....
Submersible aerial vehicle is capable of both flying in the air and submerging in the water. Advanced\nResearch Project Agency (DARPA) outlined a challenging set of requirements for a submersible aircraft and solicited\ninnovative research proposals on submersible aircraft since 2008. In this paper, a conceptual configuration design\nscheme of submersible unmanned aerial vehicle is proposed. This submersible UAV lands on the surface of water,\nthen adjusts its own density to entry water. On the contrary, it emerges from water by adjusting its own density and\nthen takes off from the surface of water. Wing of the UAV is whirling wing. It is set along aircraft�s fuselage while\nsubmerging for lift reduction. We analysis aerodynamic and hydrodynamic performance of this UAV by CFD method,\nespecially compare the hydrodynamic performance of the whirling wing configuration and normal configuration. It\nturns out that whirling wing is beneficial for submerging. This result proves that the configuration design scheme\nproposed in this paper is feasible and suitable for a submersible unmanned aerial vehicle....
A literature review of flight control technology is presented for large-scale helicopter. Challenges of large-scale helicopter flight\ncontrol system (FCS) design are illustrated. Following this, various flight control methodologies are described with respect to\ntheir engineering implementation and theoretical developments, whose advantages and disadvantages are also analyzed. Then,\nthe challenging research issues on flight control technology are identified, and future directions are highlighted....
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