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179 results on '"Friswell, M.I."'

42. Powering smart pipes with fluid flow: Effect of velocity profiles

Author

Lumentut, Mikail, Friswell, M.I., Lumentut, Mikail, and Friswell, M.I.

Abstract

The dynamics of elastic cantilevered smart pipes conveying fluid with non-uniform flow velocity profiles is presented for optimal power generation. The Navier-Stokes equations are used to model the incompressible flow in the circular smart pipe, and flow profile modification factors are formulated based on the Reynolds number and Darcy friction factor. The coupled constitutive dynamic equations, including the electrical circuit, are formulated for laminar and turbulent flows. Due to viscosity in a real fluid, non-uniform flow profiles induce dynamic stability and instability phenomena that affect the generated power. The system consists of an elastic pipe with segmented smart material located on the circumference and longitudinal regions, the circuit, and the electromechanical components. The modified coupled constitutive equations are solved using the weak form extended Ritz method. For faster convergence, this model is reduced from the exact solution of the pipe structure with proof mass offset. Initial validation with a uniform flow profile from previous work is conducted. With increasing flow velocity, the optimal power output and their frequency shifts are investigated both with and without the flow profile modification factors, to identify the level of instability. Further parametric studies with and without flow pulsation and base excitation are given.

Published
2022

49. Experimental investigation of bistable winglets to enhance wing lift takeoff capability

Author

Gatto, A., Mattioni, F., and Friswell, M.I.

Subjects
Lift (Aerodynamics) -- Analysis, Load factor design -- Analysis, Airplanes -- Wings, Airplanes -- Design and construction, Aerospace and defense industries, Business, Science and technology
Abstract

An experimental investigation into the use of a bistable winglet to enhance the lift characteristics of a wing transitioning from lower to higher subsonic flow speeds is presented in this paper. The concept centers around the use of a specifically designed composite winglet, manufactured with an unsymmetric layup, which, when increasingly loaded, snaps between two stable states. Initially, during low-speed operation, the winglet is fixed in one stable state that is specifically designed to be cambered, thus enhancing the lift capability of the wing. At higher dynamic pressures, the winglet snaps to a configuration more intuitive and conventional to current winglet design. Results presented in this paper show the concept to be viable at enhancing the lift produced by a swept wing as aerodynamic loading increases before snap-through. During snap-through, however, the absence of any method of controlling the snap-through process generated significant dynamic loading that was transmitted, unhindered, throughout the entire test rig.

Published
2009

50. Aircraft control via variable cant-angle winglets

Author

Bourdin, P., Gatto, A., and Friswell, M.I.

Subjects
Flying-machines -- Analysis, Aerospace and defense industries, Business, Science and technology
Abstract

DOI: 10.2514/1.27720 This paper investigates a novel method for the control of 'morphing' aircraft. The concept consists of a pair of winglets with adjustable cant angle, independently actuated and mounted at the tips of a baseline flying wing. The general philosophy behind the concept was that for specific flight conditions such as a coordinated turn, the use of two control devices would be sufficient for adequate control. Computations with a vortex lattice model and subsequent wind-tunnel tests demonstrate the viability of the concept, with individual and/or dual winglet deflection producing multi-axis coupled control moments. Comparisons between the experimental and computational results showed reasonable to good agreement, with the major discrepancies thought to be due to wind-tunnel model aeroelastic effects.

Published
2008

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