A Tailored Nonlinear Slat-Cove Filler for Airframe Noise Reduction

2018 ◽  
Author(s):  
Gaetano Arena ◽  
Rainer Groh ◽  
Alberto Pirrera ◽  
William Scholten ◽  
Darren Hartl ◽  
...  
Keyword(s):  
High Strain ◽  
Interaction Analysis ◽  
Effective Means ◽  
Leading Edge ◽  
Structural Behavior ◽  
Deployable Structures ◽  
Airframe Noise ◽  
Structure Interaction ◽  
Slat Noise ◽  
Displacement Constraints

Exploiting mechanical instabilities and elastic nonlinearities is an emerging means for designing deployable structures. This methodology is applied here to investigate and tailor a morphing component used to reduce airframe noise, known as a slat-cove filler (SCF). The vortices in the cove between the leading edge slat and the main wing are among the important sources of airframe noise. The concept of an SCF was proposed in previous works as an effective means of mitigating slat noise by directing the airflow along an acoustically favorable path. A desirable SCF configuration is one that minimizes: (i) the energy required for deployment through a snap-through event; (ii) the severity of the snap-through event, as measured by kinetic energy, and (iii) mass. Additionally, the SCF must withstand cyclical fatigue stresses and displacement constraints. Both composite and shape memory alloy (SMA)-based SCFs are considered during approach and landing maneuvers because the deformation incurred in some regions may not demand the high strain recoverable capabilities of SMA materials. Nonlinear structural analyses of the dynamic behavior of a composite SCF are compared with analyses of similarly tailored SMA-based SCF and a reference, uniformly thick superelastic SMA-based SCF. Results show that by exploiting elastic nonlinearities, both the tailored composite and SMA designs decrease the required actuation energy compared to the uniformly thick SMA. Additionally, the choice of composite material facilitates a considerable weight reduction where the deformation requirement permits its use. Finally, the structural behavior of the SCF designs in flow are investigated by means of preliminary fluid-structure interaction analysis.

scholarly journals Development of a SMA-Based, Slat-Cove Filler for Reduction of Aeroacoustic Noise Associated With Transport-Class Aircraft Wings

2013 ◽  
Author(s):  
Travis L. Turner ◽  
Reggie T. Kidd ◽  
Darren J. Hartl ◽  
William D. Scholten
Keyword(s):  
Computational Models ◽  
Effective Means ◽  
Leading Edge ◽  
Low Noise ◽  
Aerodynamic Load ◽  
Airframe Noise ◽  
Aircraft Wings ◽  
Aeroacoustic Noise ◽  
Slat Noise ◽  
Deformable Structure

Airframe noise is a significant part of the overall noise produced by typical, transport-class aircraft during the approach and landing phases of flight. Leading-edge slat noise is a prominent source of airframe noise. The concept of a slat-cove filler was proposed in previous work as an effective means of mitigating slat noise. Bench-top models were developed at 75% scale to study the feasibility of producing a functioning slat-cove filler. Initial results from several concepts led to a more-focused effort investigating a deformable structure based upon pseudoelastic SMA materials. The structure stows in the cavity between the slat and main wing during cruise and deploys simultaneously with the slat to guide the aerodynamic flow suitably for low noise. A qualitative parametric study of SMA-enabled, slat-cove filler designs was performed on the bench-top. Computational models were developed and analyses were performed to assess the displacement response under representative aerodynamic load. The bench-top and computational results provide significant insight into design trades and an optimal design.

Noise Reduction in a High Lift Wing Using SMAs: Computational Fluid-Structural Analysis

2016 ◽  
Author(s):  
William Scholten ◽  
Ryan Patterson ◽  
Darren Hartl ◽  
Thomas Strganac ◽  
Jeff Volpi ◽  
...  
Keyword(s):  
Structural Model ◽  
Leading Edge ◽  
Fluid Models ◽  
Cfd Analysis ◽  
High Lift ◽  
Airframe Noise ◽  
Weakly Coupled ◽  
Tunnel Model ◽  
Slat Noise ◽  
Flow Speeds

The leading-edge-slat on an aircraft is a significant contributor to the airframe noise during the low speed maneuvers of approach and landing. It has been shown in previous work that the slat noise may be reduced with a slat-cove filler (SCF). The objective of this current work is to determine how the SMA SCF behaves under steady flow using finite element structural models and finite volume (FV) fluid models based on a scaled wind tunnel model of a newly considered multi-element wing with a SCF. Computational fluid dynamics (CFD) analysis of the wing is conducted at multiple angles of attack, different flow speeds and high lift device deployment states. The FV fluid models make use of overset meshes, which overlap a slave mesh (that can undergo movement and deformation) unto a fixed master mesh, allowing for retraction and deployment of the slat and flap in the CFD analysis. The structural and fluid models are linked using a previously developed framework that permits the use of custom user material subroutines (for superelastic response of the SMA material) in the structural model, allowing for the performance of fluid-structure interaction (FSI) analysis. The fluid and structural solvers are weakly coupled such that the fluid solver transfers pressure data and the structural solver transfers displacements, but the physical quantities of each program are solved independently. FSI results are shown for the cases of the slat/SCF in the fully-deployed configuration as well as for the case of the slat/SCF undergoing retraction in flow.

Reduction of Actuation Loads in a Self-Deploying SMA-Based Slat-Cove Filler for a Transport Aircraft

2015 ◽  
Author(s):  
William Scholten ◽  
Darren Hartl ◽  
Thomas Strganac ◽  
Travis Turner
Keyword(s):  
Leading Edge ◽  
Element Analysis ◽  
Airframe Noise ◽  
Complex Load ◽  
Transport Aircraft ◽  
Actuation Force ◽  
User Subroutine ◽  
Slat Noise ◽  
Contact Complex ◽  
Force Reduction

During low speed maneuvers such as approach and landing, a significant component of the total environmental noise produced by a typical transport aircraft is associated with flow over the airframe, termed airframe noise. A key contributor to airframe noise is the leading-edge-slat, a high-lift device. Previous work showed that a slat-cove filler (SCF) may be effective at reducing the slat noise and optimal designs for an SMA-based SCF have been determined, considering stow/deploy and aerodynamic loads as well as other constraints for two realistic airframe configurations such that actuation force was minimized as the design objective. The objective of this current work is to further reduce the actuation force required to retract the SCF by an auxiliary method. The methods considered for force reduction are 1) utilization of structural instabilities in the SCF, 2) addition of auxiliary SMA actuators, and 3) replacement of selected metallic regions of the SCF with more compliant polymer-based alternatives. These methods are investigated using finite element analysis (FEA) models based on a physical bench-top model developed previously. The FEA models are also capable of modeling contact, complex load cases, and they benefit from the use of a custom user subroutine that captures the pseudoelastic response of SMA materials. For each of the three force reduction concepts considered, design optimizations are conducted using open source optimization codes and the non-dominated sorting genetic algorithm. An overall best design is proposed.

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.

State-of-the-Art Techniques for Seismic Soil-Structure Interaction Analysis of Steel Gravity Structures

2014 ◽  
Author(s):  
Frederick Tajirian ◽  
Mansour Tabatabaie ◽  
Basilio Sumodobila ◽  
Stephen Paulson ◽  
Bill Davies
Keyword(s):  
Soil Structure ◽  
State Of The Art ◽  
Interaction Analysis ◽  
Layered Soil ◽  
Soil Structure Interaction ◽  
Soil System ◽  
Cyclonic Storm ◽  
Structure Interaction ◽  
Analysis Methods ◽  
Moderate Seismicity

The design of steel jacket fixed offshore structures in zones of moderate seismicity is typically governed by Metocean loads. In contrast the steel gravity structure (SGS) presented in this paper, is a heavy and stiff structure. The large mass results in foundation forces from seismic events that may exceed those created by extreme cyclonic storm events. When computing the earthquake response of such structures it is essential to account for soil-structure interaction (SSI) effects. Seismic SSI analysis of the SGS platform was performed using state-of-the-art SSI software, which analyzed a detailed three-dimensional model of the SGS supported on layered soil system. The results of this analysis were then compared with those using industry standard impedance methods whereby the layered soil is replaced by equivalent foundation springs (K) and damping (C). Differences in calculated results resulting from the different ways by which K and C are implemented in different software are presented. The base shear, overturning moment, critical member forces and maximum accelerations were compared for each of the analysis methods. SSI resulted in significant reduction in seismic demands. While it was possible to get reasonable alignment using the different standard industry analysis methods, this was only possible after calibrating the KC foundation model with software that rigorously implements SSI effects. Lessons learned and recommendations for the various methods of analysis are summarized in the paper.

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