Design Optimization of a Piezocomposite Morphing Multi-Element Airfoil

2020 ◽  
Author(s):  
Cody Wright ◽  
Onur Bilgen
Keyword(s):  
Leading Edge ◽  
Elastic Behavior ◽  
Interaction Method ◽  
Suction Surface ◽  
High Lift ◽  
Structure Interaction ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Fuel Burn ◽  
Natural Laminar Flow

Abstract A slotted natural-laminar-flow airfoil design is a two-element airfoil design that employs a slot between the fore and aft elements. This slot alters the pressure recovery condition on the suction surface of the fore element, minimizing skin-friction and inhibiting the laminar to turbulent transition. These benefits reduce overall aircraft drag and increase wing lift. This allows smaller planforms, in turn, reducing fuel burn. This paper investigates the proposal that by help of piezocomposite surface actuation the aft element can be moved, rotated, and morphed to be used as a high-lift effector for take-off and landing conditions. A theoretical analysis is performed using a coupled fluid-structure interaction method assuming static aero-elastic behavior. During analysis the fore-element of the multi-element airfoil is assumed rigid. Thus, shape optimization is limited exclusively to the aft element. Airfoil morphing is achieved by way of piezocomposite actuating elements applied to the pressure and suction sides of the aft element. A genetic algorithm is used to independently optimize substrate thicknesses for each piezocomposite actuator as well as voltage, chord position and piezocomposite length. The nominal and leading edge substrate thicknesses of the airfoil are also varied. The optimized geometry for the high lift configuration is presented.

Fluid Structure Interaction Analysis on a Transient Pitching Hydrofoil

2009 ◽  
Author(s):  
Antoine Ducoin ◽  
Jacques Andre´ Astolfi ◽  
Franc¸ois Deniset ◽  
Jean-Franc¸ois Sigrist
Keyword(s):  
Experimental Approach ◽  
Interaction Analysis ◽  
Structural Response ◽  
Leading Edge ◽  
Video Camera ◽  
Cavitating Flows ◽  
Structure Interaction ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Edge Vortex

In this paper, the structural behavior of a deformable hydrofoil in forced pitching motion is analyzed through an experimental approach. The experimental study is based on the measurement in a hydrodynamic tunnel of the foil displacement obtained with a video camera. Tip section displacement is compared to the hydrodynamic loading obtained on a rigid hydrofoil using wall pressure measurement. The structural response appears to be strongly linked to hydrodynamic phenomena such as laminar to turbulent transition and leading edge vortex shedding. The influence of pitching velocity is discussed. Finally, the paper presents displacement measurements in cavitating flows.

High-Lift Simulations of Slotted, Natural-Laminar-Flow Airfoils with Drooped Leading Edge

2020 ◽  
Author(s):  
Hector D. Ortiz-Melendez ◽  
Ethan Long ◽  
George Toth ◽  
Kathryn Keely ◽  
James G. Coder
Keyword(s):  
Laminar Flow ◽  
Leading Edge ◽  
High Lift ◽  
Natural Laminar Flow

Effects of periodic wakes on boundary layer development on an ultra-high-lift low pressure turbine airfoil

2016 ◽  
Vol 231 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Xingen Lu ◽  
Yanfeng Zhang ◽  
Wei Li ◽  
Shuzhen Hu ◽  
Junqiang Zhu
Keyword(s):  
Boundary Layer ◽  
Transition Process ◽  
Low Pressure ◽  
Suction Surface ◽  
High Lift ◽  
Low Pressure Turbine ◽  
Turbulent Transition ◽  
Boundary Layer Development ◽  
Unsteady Wake ◽  
Layer Development

The laminar-turbulent transition process in the boundary layer is of significant practical interest because the behavior of this boundary layer largely determines the overall efficiency of a low pressure turbine. This article presents complementary experimental and computational studies of the boundary layer development on an ultra-high-lift low pressure turbine airfoil under periodically unsteady incoming flow conditions. Particular emphasis is placed on the influence of the periodic wake on the laminar-turbulent transition process on the blade suction surface. The measurements were distinctive in that a closely spaced array of hot-film sensors allowed a very detailed examination of the suction surface boundary layer behavior. Measurements were made in a low-speed linear cascade facility at a freestream turbulence intensity level of 1.5%, a reduced frequency of 1.28, a flow coefficient of 0.70, and Reynolds numbers of 50,000 and 100,000, based on the cascade inlet velocity and the airfoil axial chord length. Experimental data were supplemented with numerical predictions from a commercially available Computational Fluid Dynamics code. The wake had a significant influence on the boundary layer of the ultra-high-lift low pressure turbine blade. Both the wake’s high turbulence and the negative jet behavior of the wake dominated the interaction between the unsteady wake and the separated boundary layer on the suction surface of the ultra-high-lift low pressure turbine airfoil. The upstream unsteady wake segments convecting through the blade passage behaved as a negative jet, with the highest turbulence occurring above the suction surface around the wake center. Transition of the unsteady boundary layer on the blade suction surface was initiated by the wake turbulence. The incoming wakes promoted transition onset upstream, which led to a periodic suppression of the separation bubble. The loss reduction was a compromise between the positive effect of the separation reduction and the negative effect of the larger turbulent-wetted area after reattachment due to the earlier boundary layer transition caused by the unsteady wakes. It appeared that the successful application of ultra-high-lift low pressure turbine blades required additional loss reduction mechanisms other than “simple” wake-blade interaction.

scholarly journals Experimental Investigation of Transition to Turbulence as Affected by Passing Wakes

2001 ◽  
Author(s):  
Richard W. Kaszeta ◽  
Terrence W. Simon ◽  
David E. Ashpis
Keyword(s):  
Reynolds Number ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Turbine Engines ◽  
Bypass Transition ◽  
Pressure Gradients ◽  
Suction Surface ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Near Wall

This paper presents experimental results from a study of the effects of periodically passing wakes upon laminar-to-turbulent transition and separation in a low-pressure turbine passage. The test section geometry is designed to simulate unsteady wakes in turbine engines for studying their effects on boundary layers and separated flow regions over the suction surface by using a single suction surface and a single pressure surface to simulate a single turbine blade passage. Single-wire, thermal anemometry techniques are used to measure time-resolved and phase-averaged, wall-normal profiles of velocity, turbulence intensity and intermittency at multiple streamwise locations over the turbine airfoil suction surface. These data are compared to steady-state wake-free data collected in the same geometry to identify the effects of wakes upon laminar-to-turbulent transition. Results are presented for flows with a Reynolds number based on suction surface length and stage exit velocity of 50,000 and an approach flow turbulence intensity of 2.5%. While both existing design and experimental data are primarily concerned with higher Reynolds number flows (Re > 100,000), recent advances in gas turbine engines, and the accompanying increase in laminar and transitional flow effects, have made low-Re research increasingly important. From the presented data, the effects of passing wakes on transition and separation in the boundary layer, due to both increased turbulence levels and varying streamwise pressure gradients are presented. The results show how the wakes affect transition. The wakes affect the flow by virtue of their difference in turbulence levels and scales from those of the free-stream and by virtue of their ensemble-averaged velocity deficits, relative to the free-stream velocity, and the concomitant changes in angle of attack and temporal pressure gradients. The relationships between the velocity oscillations in the freestream and the unsteady velocity profile shapes in the near-wall flow are described. In this discussion is support for the theory that bypass transition is a response of the near-wall viscous layer to pressure fluctuations imposed upon it from the free-stream flow. Recent transition models are based on that premise. The data also show a significant lag between when the wake is present over the surface and when transition begins.

A Study on Fluid-Structure Interaction Performance of a Flexible Hydrofoil

2018 ◽  
Author(s):  
Zheng Huang ◽  
Ying Xiong ◽  
Ye Xu ◽  
Shancheng Li
Keyword(s):  
Center Of Pressure ◽  
Separation Bubble ◽  
Fluid Structure Interaction ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Fluid Structure ◽  
Maximum Deformation ◽  
Structure Interaction ◽  
Turbulent Transition

To research the flexible hydrofoils’ hydroelastic response, the fluid-structure interaction (FSI) characteristic investigation is conducted on the basis of the analysis of a rigid hydrofoil’s hydrodynamic performance. For a rigid cantilevered rectangular hydrofoil, the pitching hydrodynamic performance is calculated using boundary motion with remeshing strategy. The Laminar Separation Bubble (LSB) and turbulent transition are captured. Numerical flow analysis revealed that the LSB occurs at 0.8c when pitching at initial angle of attack. As the angle increases to 5.1°, the laminar to turbulent transition occurs and the lift presents an inflection. For a geometric equivalent flexible hydrofoil, the static FSI characteristic is researched using oneway and two-way FSI method. The lift decreases and the drag increases using two-way compared to one-way FSI. The center of pressure and the maximum deformation move from trailing edge to leading edge as the angle of attack increases, showing the necessary of two-way FSI calculation. The transient FSI characteristic of the flexible hydrofoil is then studied using LES model. The lift fluctuation at 8° in frequency domain is calculated . The dry mode and wet mode natural frequency of the flexible hydrofoil are calculated to simulate the vibration performance, which meet the experiment data quite well, laying foundation for further research on the hydroelastic vibration response.

Visualization of Flow Field and Wake over Clean and Under-Loaded Wings

2014 ◽  
Vol 629 ◽  
pp. 24-29
Author(s):  
Hussain H. Al-Kayiem
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Flow Field ◽  
Visualization Technique ◽  
High Lift ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Wake Interaction ◽  
Airfoil Flow ◽  
External Body

Experimental details of the flow field and wake over airfoils and 2-D wings are time and cost consumption. In this study, the flow visualization technique was adopted to investigate the flow field surrounding NACA4412 airfoil. The investigations were carried out in smoke tunnel, operating at low Reynolds number in a range of 105. The airfoil was tested in two operational cases: first as clean wing and the second as under-loaded wing by attached missile model. The experiments were conducted at various angles of attack as 00, 50,100, 150and 200. It was found that the under-load of external body under the wing is influencing the flow structure over the wing. Also, the wake after the external body is swirling, leading to very complicated wake interaction. The results from the work can support the numerical simulation and the prediction of the laminar to turbulent transition and the separation and wake interaction of high lift airfoil flow fields.

A Variable Camber Piezocomposite Trailing-Edge for Subsonic Aircraft: Multidisciplinary Design Optimization

2019 ◽  
Author(s):  
Cody Wright ◽  
Onur Bilgen
Keyword(s):  
Genetic Algorithm ◽  
Fuel Efficiency ◽  
Leading Edge ◽  
Optimization Method ◽  
Population Diversity ◽  
Elastic Behavior ◽  
Algorithm Optimization ◽  
Migration Strategy ◽  
High Lift ◽  
Reynold’S Number

Abstract A continuous-surface morphing airfoil is desirable for commercial aircraft in order to improve fuel efficiency, and due to the potential to morph the wing into a high-lift configuration for take-off and landing. Piezocomposite actuators have shown to be a feasible strategy for camber morphing in small unmanned fixed-wing aircraft with a Reynold’s number in the range of 50,000 to 250,000. As an extension, this paper presents a theoretical framework and results for morphing in single and multi-segment natural laminar flow airfoils with a maximum Reynold’s number of 825,000. The airfoils presented employ a continuous inextensible surface. To achieve morphing, piezocomposite actuating elements are applied on the suction and pressure surfaces of the airfoils. The geometric properties of the airfoils are determined using a genetic algorithm optimization method with a migration strategy in order to maintain population diversity. The algorithm optimizes independently the substrate thicknesses for the nominal airfoil, the leading edge, and the piezocomposite bonded surfaces. In addition, positions and voltages for each piezocomposite actuators are optimized. The genetic algorithm uses an objective function to maximize the change in coefficient of lift to morph the airfoil from its baseline (i.e. cruise) state to the high-lift state. Analysis is performed using a coupled fluid-structure interaction method assuming static aero-elastic behavior. Optimization is followed by a parametric analysis to examine lift, drag, and lift-to-drag ratio of the airfoils over their full operational range. The optimization is performed on a symmetric, asymmetric, and the aft element of a slotted multi-segment airfoil to examine the capabilities of induced-strain actuation at high dynamic pressures.

scholarly journals Aerodynamic Shape Design and Validation of an Advanced High-Lift Device for a Regional Aircraft with Morphing Droop Nose

2019 ◽  
Vol 2019 ◽  
pp. 1-21 ◽  
Author(s):  
Alessandro De Gaspari ◽  
Frédéric Moens
Keyword(s):  
Laminar Flow ◽  
Tracking System ◽  
Three Dimensional ◽  
Design Procedure ◽  
Leading Edge ◽  
Optimization Procedure ◽  
Shape Design ◽  
High Lift ◽  
Aerodynamic Shape ◽  
Natural Laminar Flow

In the present work, the aerodynamic shape design of an advanced high-lift system for a natural laminar flow (NLF) wing, based on the combination of a morphing droop nose and a single slot trailing edge flap, is presented. The paper presents both the aerodynamic design and optimization of the NLF wing and the high-lift configuration considering the mutual effects of both flap devices. Concerning the morphing droop nose (DN), after defining the parameterization techniques adopted to describe the geometry in terms of morphing shape and flap settings, the external configuration is obtained by an aerodynamic shape optimization procedure able to meet geometrical constraints and the skin structural requirements due to the morphing. The final performance assessment of the three-dimensional high-lift configurations is performed by high-fidelity aerodynamic analyses. The design procedure is applied to a twin-prop regional aircraft equipped with a natural laminar flow wing. The morphing droop nose is compatible with an NLF wing that requires the continuity of the skin and, at the same time, extends the possibilities to improve the performances of the class of regional aircraft which usually are not equipped with conventional leading edge devices. Additionally, the morphing technology applied to the flap allows the design of a tracking system fully integrated inside the airfoil geometry, leading to a solution without external fairings and so with no extra friction drag penalty for the aircraft.

INFLUENCE OF THE PLATE LEADING-EDGE SHAPE AND THICKNESS ON THE BOUNDARY LAYER LAMINAR-TURBULENT TRANSITION IN HYPERSONIC FLOW

2019 ◽  
Vol 50 (5) ◽  
pp. 461-481
Author(s):  
Sergei Vasilyevich Aleksandrov ◽  
Evgeniya Andreevna Aleksandrova ◽  
Volf Ya. Borovoy ◽  
Andrey Vyacheslavovich Gubernatenko ◽  
Vladimir Evguenyevich Mosharov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Hypersonic Flow ◽  
Leading Edge ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition
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