Acquisition of Swept Aerodynamic Data by the Consecutive Changing of Wing Model Configuration in a Wind Tunnel Test Using Remote Feedback Control

This study conducted wind tunnel tests with consecutive deflection angle changes on a three-dimensional (3D) wing with a control surface to procure aerodynamic data by sweeping the deflection angle. Configuration changes of a wind tunnel test model, such as changing the deflection angle of control surfaces, are usually performed manually with the ventilation suspended. Hence, the number of configurations that can be implemented within a confined test period is restricted; the aerodynamic data gained are discrete values. To accomplish continuous angular modulation would dramatically improve the ability by sweeping through the aerodynamic data in wind tunnel tests, enhancing the test system as a tool for discussing complex physical phenomena. Thus, this study created a compact remote feedback control system using optical measurement to continuously obtain high-precision aerodynamic data without stopping the wind tunnel, eliminating human operation. In particular, this study targets a 3D wing wind tunnel model with a control surface, which is more challenging to fabricate, miniaturizing the system in a model. The system consequently attained consecutive aerodynamic data multiple times under numerous configurations, which had been impracticable to reach in the past, within a wind tunnel test period of several days, thereby dramatically increasing the testing capability. The reproducibility was quantitatively verified by comparing the multiple data for the identical configurations. Furthermore, the reliability was demonstrated using discrete data obtained by conventional stepwise deflection angle adjustments. Eventually, the system was able to grasp physical phenomena involving hysteresis.

Simulations of Aerodynamic Separated Flows Using the Lattice Boltzmann Solver XFlow

We present simulations of turbulent detached flows using the commercial lattice Boltzmann solver XFlow (by Dassault Systemes). XFlow’s lattice Boltzmann formulation together with an efficient octree mesh generator reduce substantially the cost of generating complex meshes for industrial flows. In this work, we challenge these meshes and quantify the accuracy of the solver for detached turbulent flows. The good performance of XFlow when combined with a Large-Eddy Simulation turbulence model is demonstrated for different industrial benchmarks and validated using experimental data or fine numerical simulations. We select five test cases: the Backward-facing step the Goldschmied Body the HLPW-2 (2nd High-Lift Prediction Workshop) full aircraft geometry, a NACA0012 under dynamic stall conditions and a parametric study of leading edge tubercles to improve stall behavior on a 3D wing.

Crosswise Wind Shear Represented as a Ramped Velocity Profile Impacting a Forward-Moving Aircraft

Abrupt changes in wind velocities over small distances in a lateral or vertical direction can produce wind shear which is known to have serious effects upon the performance of an aircraft. Brought about by large-scale changes in the atmospheric conditions, it is a three-dimensional flow phenomenon imposing severe velocity gradients on an aircraft from all possible directions. While it would be difficult to model an instantaneous velocity gradient in a lateral plane, a vortical flow impinging from the sides which represents a wind shear in a vertical direction is imposed on a forward-moving aircraft to investigate the effect on the aerodynamic performance. The maximum shear wind speed from the side was fixed at 0.3 times the forward velocity. After due validations under no-wind shear conditions on simpler half-reflection plane models, a BGK airfoil-based full 3D wing and the ONERA M6 3D wing model were selected for preliminary studies. The investigation was concluded using the ARA M100 wing-fuselage model.

Computational Analysis of 3D Lattice Structures for Skin in Real-Scale Camber Morphing Aircraft

Conventional or fixed wings require a certain thickness of skin material selection that guarantees structurally reliable strength under expected aerodynamic loadings. However, skin structures of morphing wings need to be flexible as well as stiff enough to deal with multi-axial structural stresses from changed geometry and the coupled aerodynamic loadings. Many works in the design of skin structures for morphing wings take the approach either of only geometric compliance or a simplified model that does not fully represent 3D real-scale wing models. Thus, the main theme of this study is (1) to numerically identify the multi-axial stress, strain, and deformation of skin in a camber morphing wing aircraft under both structure and aerodynamic loadings, and then (2) to show the effectiveness of a direct approach that uses 3D lattice structures for skin. Various lattice structures and their direct 3D wing models have been numerically analyzed for advanced skin design.

Lift Generation of an Elliptical Airfoil at a Reynolds Number of 1000

Bumblebees cannot fly! That conclusion is likely to be drawn by scientists who analysed the insect using aerodynamics of stationary wings such as that of a passenger aircraft. Looking at the insect again using a newfound understanding of unsteady aerodynamics; it is clear why bumblebees can fly. Bumblebees utilise mechanisms behind unsteady aerodynamics such as leading-edge vortices (LEVs) formation, wake capture, and rapid end-of-stroke rotation to generate forces that enable the insect to fly. This study focuses on two-dimensional (2D) elliptical airfoil. Earlier works found the aerodynamic characteristics of an elliptical airfoil to differ greatly from a conventional airfoil, and that this airfoil shape could generate the counter-rotating vortices used by insects to generate lift. Therefore, this research aims to study the lift generation of a bumblebee-inspired elliptical airfoil in a normal hovering flight. This study focuses on hovering flight with the insect flies in a nearly stationary position, which explains the importance of lift generation to stay aloft. The motion of the elliptical airfoil is inspired by the flapping kinematics of bumblebees at a typical Reynolds number range of . It is found that the current two-dimensional model is capable of capturing the counter-rotating vortices and correlates the formation of these structures to a high production of lift. These results show that bumblebees utilise these counter-rotating vortices to generate lift enough to fly in hovering flight. This results also indicate that flapping 2D elliptical airfoils can be used to investigate their 3D wing counterparts, which translate to a reduced time and computing costs.