This paper investigates a dual-timescale autopilot for a wing-damaged airplane applying nonlinear adaptive sliding mode approach. The adaptive flight control strategy is used to track outer-loop angle commands while accommodating wing damage effect. Two distinct adaptive sliding mode control strategies are designed for the inner- and outer-loop dynamics. The airplane nonlinear model is developed considering center of gravity shift and aerodynamic changes due to the asymmetric wing damage. The performance of the proposed nonlinear adaptive sliding mode controller is evaluated through numerical simulation on NASA generic transport model and is compared with two adaptive algorithms: model reference adaptive control and a robust adaptive control strategy. The results demonstrate that the proposed control law achieves closed-loop stability in the presence of wing damage and accelerometers bias, and also provides satisfactory tracking performance.
Purpose Water/Al2O3 nanofluid with volume fractions of 0, 0.3 and 0.06 was investigated inside a rectangular microchannel. Jet injection of nanofluid was used to enhance the heat transfer under a homogeneous magnetic field with the strengths of Ha = 0, 20 and 40. Both slip velocity and no-slip boundary conditions were used.
Design/methodology/approach The laminar flow was studied using Reynolds numbers of 1, 10 and 50. The results showed that in creep motion state, the constricted cross section caused by fluid jet is not observable and the rise of axial velocity level is only because of the presence of additional size of the microchannel. By increasing the strength of the magnetic field and because of the rise of the Lorentz force, the motion of fluid layers on each other becomes limited.
Findings Because of the limitation of sudden changes of fluid in jet injection areas, the magnetic force compresses the fluid to the bottom wall, and this behavior limits the vertical velocity gradients. In the absence of a magnetic field and under the influence of the velocity boundary layer, the fluid motion has more variations. In creeping velocities of fluid, the presence or absence of the magnetic field does not have an essential effect on Nusselt number enhancement.
Originality/value In lower velocities of fluid, the effect of the jet is not significant, and the thermal boundary layer affects the entire temperature field. In this case, for Hartmann numbers of 40 and 0, changing the Nusselt number on the heated wall is similar.
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