Direct numerical simulations (DNS) of flow over an NACA-0012 airfoil are performed at a low and a moderate Reynolds numbers of Rec=50*10 and 1*10. The angles of attack are 5 and 15 degrees at the low and the moderate Reynolds number cases respectively. The three-dimensional unsteady compressible Navier-Stokes equations are solved using higher order compact schemes. The flow field in the low Rey...

This paper demonstrates a new performance enhancement methodology for Co-Flow Jet (CFJ) airfoils using discrete injection jets. This research is motivated by the hypothesis that a discrete CFJ (DCFJ) airfoil will generate both streamwise and spanwise vortex structures to achieve more effective turbulent mixing than an open slot CFJ airfoil. Aerodynamic forces and DPIV measurements show that the...

High-fidelity numerical simulations with the spectral difference (SD) method are carried out to investigate the unsteady flow over a series of oscillating NACA 4-digit airfoils. Airfoil thickness and kinematics effects on the flapping airfoil propulsion are highlighted. It is confirmed that the aerodynamic performance of airfoils with different thickness can be very different under the same kin...

This paper applies a Reinforcement Learning methodology to the problem of airfoil morphing. The reinforcement learning as it is applied to morphing is integrated with a computational model of an airfoil. The computational model utilizes a doublet panel method whose end yield is airfoil lift, drag, and moment coefficients. An episodic unsupervised learning simulation using the Q-Learning method ...

An experimental study was conducted to investigate the aerodynamic characteristics of a bio-inspired corrugated airfoil compared with a streamlined airfoil and a flat plate at the chord Reynolds number of Re= 58,000 ~ 125,000 to explore the potential applications of such bio-inspired corrugated airfoils for micro air vehicle (MAV) designs. In addition to measuring the aerodynamic lift and drag ...

An implicit, Navier-Stokes solution algorithm is presented for the computation of turbulent flow on unstructured grids. The inviscid fluxes are computed using an upwind algorithm and the solution is advanced in time using a backward-Euler time-stepping scheme. At each time step, the linear system of equations is approximately solved with a point-implicit relaxation scheme. This methodology prov...

An episodic unsupervised learning algorithm using the Q-Learning method is developed to learn the optimal shape and shape change policy of a morphing airfoil. Optimality is addressed by reward functions based on airfoil properties such as lift coefficient, drag coefficient, and moment coefficient about the leading edge representing optimal shapes for specified flight conditions. The reinforceme...

in this paper, the effect of electric field on two-dimensional low reynolds air flow around an airfoil and variation of the forces acting on the airfoil is numerically investigated. the electric current and poisson’s equations are solved and the outcome is considered as a source term in the momentum equations. the energy equation is not considered due to its weak effect on the phenomena. the fi...

Icing is widely recognized as one of the most serious weather hazards to aircraft operations. Aircraft icing occurs when small, super-cooled, airborne water droplets, which make up clouds and fog, freeze upon impact with a surface, which results in the formation of ice (Mason 1971). The freezing can be complete or partial, depending on how rapidly the latent heat of fusion can be released into ...

The unsteady load response of an airfoil encountering a gust is often modeled using analytical transfer functions, which assume idealized behavior both the flow and airfoil. One such function Sears function, models pure transverse interacting with flat-plate at zero mean incidence. was extended by Goldstein Atassi (“A Complete Second-Order Theory for Unsteady Flow About Airfoil due to Periodic ...