Airfoil

About: Airfoil is a research topic. Over the lifetime, 24696 publications have been published within this topic receiving 337709 citations. The topic is also known as: aerofoil & wing section.

Boundary Layer Development in Axial Compressors and Turbines: Part 2 of 4—Compressors

Abstract: This is Part Two of a four-part paper. It begins with Section 6.0 and continues to describe the comprehensive experiments and computational analyses that have led to a detailed picture of boundary layer development on airfoil surfaces in multistage turbomachinery. In this part, we present the experimental evidence used to construct the composite picture for compressors given in the discussion in Section 5.0 of Part 1. We show the data from the surface hot-film gages and the boundary layer surveys, give a thorough interpretation for the baseline operating condition, and then show how this picture changes with variations in Reynolds number, airfoil loading, frequency of occurrence of wakes and wake turbulence intensity. Detailed flow features are described using raw time traces. The use of rods to simulate airfoil wakes is also evaluated.

Aerodynamic characteristics of a two-dimensional airfoil with ground effect

Abstract: The effect of Reynolds number on the aerodynamic characteristics of an airfoil with ground effect in viscous flow is investigated by numerical method. A numerical scheme, based on the standard k-e turbulence model, generalized body-fixed coordinates and the finite volume method, is developed to solve the two-dimensional wing-in-ground problem hi viscous flow. The steady, incompressible Navier-Stokes equations are solved using a grid generation program developed by the authors, and the PHOENICS code. Some numerical results are presented to show the effects of Reynolds number, ground clearance, and angles of attack on the aerodynamic characteristics of a NACA 4412 airfoil.

Mechanisms for laminar separated-flow control using dielectric-barrier-discharge plasma actuator at low Reynolds number

Abstract: Large-eddy simulations have been conducted to investigate the mechanisms of separated-flow control using a dielectric barrier discharge plasma actuator at a low Reynolds number. In the present study, the mechanisms are classified according to the means of momentum injection to the boundary layer. The separated flow around the NACA 0015 airfoil at a Reynolds number of 63 000 is used as the base flow for separation control. Both normal and burst mode actuations are adopted in separation control. The burst frequency non-dimensionalized by the freestream velocity and the chord length (F+) is varied from 0.25 to 25, and we discuss the control mechanism through the comparison of the aerodynamic performance and controlled flow-fields in each normal and burst case. Lift and drag coefficients are significantly improved for the cases of F+ = 1, 5, and 15 due to flow reattachment associated with a laminar-separation bubble. Frequency and linear stability analyses indicate that the F+ = 5 and 15 cases effectively exc...

On the Influence of Time-Varying Flow Velocity on Unsteady Aerodynamics.

Abstract: The effects of a periodic free-stream velocity on the unsteady aerodynamics of an airfoil in incompressible flow are examined. Existing theories are reviewed, and their simplifications and limitations are properly identified. A new general aerodynamic theory for an airfoil undergoing a combination of harmonic pitching, plunging and fore-aft motion is presented. An extension to arbitrary free-stream velocity variations and arbitrary airfoil motion is also given. The theoretical results are validated against numerical predictions made by a modern Euler code.