Coupled dynamics of steady jet flow control for flexible membrane wings

We present a steady jet flow-based flow control of flexible membrane wings for an adaptive and efficient motion of bat-inspired drones in complex flight environments. A body-fitted variational computational aeroelastic framework is adopted for the modeling of fluid-structure interactions. High-momentum jet flows are injected from the leading edge and transported to the wake flows to alter the aerodynamic performance and the membrane vibration. The phase diagrams of the coupled fluid-membrane dynamics are constructed in the parameter space of the angle of attack and the jet momentum coefficient. The coupled dynamical effect of active jet flow control on the membrane performance is systematically explored. While the results indicate that the current active flow control strategy performs well at low angles of attack, the effectiveness degrades at high angles of attack with large flow separation. To understand the coupling mechanism, the variations of the vortex patterns at different jet momentum coefficients are examined by the proper orthogonal decomposition modes in the Eulerian view and the fluid transport process is studied by the coherent flow structures in the Lagrange description. Two scaling relations that quantitatively connect the membrane deformation with the aerodynamic loads presented in our previous work are verified even when active jet flow control is applied. A unifying feedback loop that reveals the fluid-membrane coupling mechanism is proposed. This feedback loop provides useful guidance for designing optimal active flow control strategies and enhancing flight capabilities. These findings can facilitate the development of next-generation bio-inspired drones that incorporate smart sensing and intelligent control

2D flow around stationary side-by-side square columns at low Reynolds number

Flow over two side-by-side square columns is studied numerically and experimentally at low Reynolds number (Re=100-200) to investigate the effects of the gap distance on the behaviour of the flow. Different gap distances between two square columns are simulated to analyse the interactions of laminar wakes with a gap flow. Four different flow regimes are observed based on different gap distance. Experimental test are performed to validate the simulations. A new water tank has been built specifically for these tests due to the requirements of low Reynolds number and the high sensitivity of the gap flow. Initial experimental flow visualizations of the vortex wake confirm the findings of distinct gap flow regimes

Numerical study of the flow interference between tandem cylinders employing non-linear hybrid URANS-LES methods

10.1016/j.jweia.2015.03.017Journal of Wind Engineering and Industrial Aerodynamics142111-12