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.

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 Analysis-Driven Design Optimization of a SMA-Based Slat-Cove Filler for Aeroacoustic Noise Reduction

2013 ◽  
Author(s):  
William Scholten ◽  
Darren Hartl ◽  
Travis Turner
Keyword(s):  
Structural Response ◽  
Leading Edge ◽  
Optimized Design ◽  
Analysis Model ◽  
Element Analysis ◽  
Airframe Noise ◽  
Aeroacoustic Noise ◽  
Aerodynamic Pressure ◽  
Configuration Change ◽  
Design Variables

Airframe noise is a significant component of environmental noise in the vicinity of airports. The noise associated with the leading-edge slat of typical transport aircraft is a prominent source of airframe noise. Previous work suggests that a slat-cove filler (SCF) may be an effective noise treatment. Hence, development and optimization of a practical slat-cove-filler structure is a priority. The objectives of this work are to optimize the design of a functioning SCF that incorporates superelastic shape memory alloy (SMA) materials as flexures that permit the deformations involved in the configuration change. The goal of the optimization is to minimize the actuation force needed to retract the slat-SCF assembly while satisfying constraints on the maximum SMA stress and on the SCF deflection under static aerodynamic pressure loads, while also satisfying the condition that the SCF self-deploy during slat extension. A finite element analysis model based on a physical bench-top model is created in Abaqus such that automated iterative analysis of the design could be performed. In order to achieve an optimized design, several design variables associated with the current SCF configuration are considered, such as the thicknesses of SMA flexures and the dimensions of various components, SMA and conventional. Design of experiment (DOE) studies are performed to investigate structural response to an aerodynamic pressure load and to slat retraction and deployment. DOE results are then used to inform the optimization process, which determines a design minimizing actuator forces while satisfying the required constraints.

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.

Flow Around a Leading-Edge Slat: Part I — Turbulent Flow Statistics

2014 ◽  
Author(s):  
Patrick R. Richard ◽  
Stephen J. Wilkins ◽  
Joseph W. Hall
Keyword(s):  
Leading Edge ◽  
Aircraft Engine ◽  
Reynolds Numbers ◽  
Small Scale ◽  
Reynolds Stresses ◽  
Airframe Noise ◽  
Aeroacoustic Noise ◽  
Image Velocimetry ◽  
Strong Shear ◽  
The University

As aircraft engine noise continues to decrease with advancing research, the focus has been partially shifted to airframe noise. One of the main sources of airframe noise are high lift devices, which includes the leading-edge slat on wings. The leading-edge slat works along with the tail flap to provide increased lift to the aircraft during takeoff and landing. This paper will present the findings of an experimental investigation aimed at identifying the sources of noise produced by the leading-edge slat geometry. The main focus of the experiments was the slat cove. Small scale wind tunnel experiments were undertaken at the University of New Brunswick using Particle Image Velocimetry (PIV) to obtain time-averaged Turbulent Kinetic Energy (TKE), Reynolds stresses and vorticity. The experiments were performed at Reynolds numbers of 156,000 and 312,000 for an angle of attack of 20 degrees. The results indicate the presence of a strong shear-layer formed at the slat cusp which is likely to be an significant source of aeroacoustic noise.

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.

The effect of doors and cavity on the aerodynamic noise of fuselage nose landing gear

2021 ◽  
pp. 1475472X2110032
Author(s):  
Yongfei Mu ◽  
Jie Li ◽  
Wutao Lei ◽  
Daxiong Liao
Keyword(s):  
Separated Flow ◽  
Leading Edge ◽  
Landing Gear ◽  
Aerodynamic Noise ◽  
Sound Waves ◽  
Detached Eddy Simulation ◽  
Airframe Noise ◽  
Interference Phenomenon ◽  
Delayed Detached Eddy Simulation ◽  
The Doors

The aerodynamic noise of landing gears have been widely studied as an important component of the airframe noise. During take-off and landing, there are doors, cavity and fuselage around the landing gear. The noise caused by these aircraft components will interfere with aerodynamic noise generated by the landing gear itself. Hence, paper proposes an Improved Delayed Detached Eddy Simulation (IDDES) method for the investigation of the flow field around a single fuselage nose landing gear (NLG) model and a fuselage nose landing gear model with doors, cavity and fuselage nose (NLG-DCN) respectively. The difference between the two flow fields were analyzed in detail to better understand the influence of these components around the aircraft’s landing gear, and it was found that there is a serious mixing phenomenon among the separated flow from the front doors, the unstable shear layer falling off the leading edge of the cavity and the wake of the main strut which directly leads to the enhancement of the noise levels. Furthermore, after the noise sound waves are reflected by the doors several times, an interference phenomenon is generated between the doors. This interference may be a reason why the tone excited in the cavity is suppressed.

Experimental Results From Controlled Blade Tip/Shroud Rubs at Engine Speed

2006 ◽  
Author(s):  
Corso Padova ◽  
Jeffery Barton ◽  
Michael G. Dunn ◽  
Steve Manwaring
Keyword(s):  
Computational Models ◽  
Engine Speed ◽  
Leading Edge ◽  
Experimental Results ◽  
Trailing Edge ◽  
Metal On Metal ◽  
Non Linear ◽  
Blade Tip ◽  
Force Components ◽  
Tip Shroud

Experimental results obtained for an Inconel compressor blade rubbing a steel casing at engine speed are described. Load cell, strain gauge and accelerometer measurements are discussed and then applied to analyze the metal-on-metal interaction resulting from sudden incursions of varying severity, defined by incursion depths ranging from 13 μm to 762 μm (0.0005-in to 0.030-in). The results presented describe the transient dynamics of rotor and casing vibro-impact response at engine operational speed similar to those experienced in flight. Force components at the blade tip in axial and circumferential directions for a rub of moderate incursion depth (140 μm) are compared to those for a severe rub (406 μm). Similar general trends of variation during the metal-to-metal contact are observed. However, in the nearly three-fold higher incursion the maximum incurred circumferential load increases significantly, while the maximum incurred axial load increases much less, demonstrating the non-linear nature of the rub phenomena. Concurrently, the stress magnification on the rubbing blade at root mid-chord, at tip leading edge, and at tip trailing edge is discussed. The results point to the possibility of failure occurring first at the airfoil trailing edge. Such a failure was in fact observed in the most severe rub obtained to date in the laboratory, consistent with field observations. Computational models to analyze the non-linear dynamic response of a rotating beam with periodic pulse loading at the free-end are currently under development and are noted.

Aeroacoustic Study on a Simplified Nose Landing Gear

2012 ◽  
Vol 184-185 ◽  
pp. 18-23 ◽  
Author(s):  
Shuang Li Long ◽  
Hong Nie ◽  
Xin Xu
Keyword(s):  
Simulation Analysis ◽  
Sound Field ◽  
Low Noise ◽  
Landing Gear ◽  
Broadband Noise ◽  
Detached Eddy Simulation ◽  
Gear Design ◽  
Aeroacoustic Noise ◽  
Eddy Simulation ◽  
Landing Gear Noise

Simulation analysis and experiment research are performed on the aeroacoustic noise of a landing gear component in this paper. Detached Eddy Simulation (DES) is used to produce the flow field of the model. The Ffowcs-Williams/Hawkings (FW-H) equation is used to calculate the acoustic field. The sound field radiated from the model is measured in the acoustic wind tunnel. A comparison shows that the simulation results agree well with the experiment results under the acoustic far field condition. The results show that the noise radiated from the model is broadband noise. The directivity of the noise source is like a type of dipole. The wheel is the largest contributor and the strut is the least contributor to the landing gear noise. The results can provide some reference for low noise landing gear design.

scholarly journals Experiments on the Effects of Reynolds Number and Advance Ratio on the Unfolding of Disorganization in Low-Speed Underwater Propulsors With Vibrating Blades

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Promode R. Bandyopadhyay
Keyword(s):  
Acoustic Radiation ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Limit Cycle Oscillation ◽  
Blade Vibration ◽  
Low Reynolds Numbers ◽  
Low Speed ◽  
Aircraft Wings ◽  
Wall Boundary Layer ◽  
Cycle Oscillation

Ships and submarines are acoustic hazards to marine life. The rational control of acoustic radiation would be possible at least at low Reynolds numbers if the underlying organization buried in seeming randomness is revealed. We build a novel low-speed propulsor where all blades undergo small-amplitude pitch oscillation while spinning at large pitch angles at transitional chord Reynolds numbers (3.75 × 103 ≤ Rec ≤ 3.75 × 104) and advance ratios (0.51 ≤ J ≤ 4.89). We measure and model time-averaged and temporal thrust. The relationship between the time-averaged and the temporal thrust is observed when the latter is mapped as limit cycle oscillation (LCO), or departure from it. High-thrust coefficients occurring at large (30 deg and 45 deg) angles of amplitude of blade vibration are modeled assuming poststall lift enhancement due to flapping blades when a leading edge vortex (LEV) forms, while the lower thrust coefficients occurring at 20 deg are modeled by its absence. The disorganization in temporal thrust increases with J and Rec. An external orthogonal oscillator, perhaps a vibration, is modeled to couple with the thrust oscillator for temporal control of disorganization. The unfolding disorganization is seen as a departure from LCO, and it is attenuated by smooth-wall boundary-layer fencing, compared to unfenced smooth and rough surfaces. When the fencing properties of the leading edge tubercles of whale fins are recognized, the ratio of the spacing of the fences and chord is found to be similar (0.5–1.0) in both whale flippers and aircraft wings.

Experimental Results From Controlled Blade Tip/Shroud Rubs at Engine Speed

2006 ◽  
Vol 129 (4) ◽  
pp. 713-723 ◽  
Author(s):  
Corso Padova ◽  
Jeffery Barton ◽  
Michael G. Dunn ◽  
Steve Manwaring
Keyword(s):  
Computational Models ◽  
Engine Speed ◽  
Leading Edge ◽  
Experimental Results ◽  
Trailing Edge ◽  
Metal On Metal ◽  
Non Linear ◽  
Blade Tip ◽  
Force Components ◽  
Tip Shroud

Experimental results obtained for an Inconel® compressor blade rubbing a steel casing at engine speed are described. Load cell, strain gauge, and accelerometer measurements are discussed and then applied to analyze the metal-on-metal interaction resulting from sudden incursions of varying severity, defined by incursion depths ranging from 13μm to 762μm (0.0005in. to 0.030in.). The results presented describe the transient dynamics of rotor and casing vibro-impact response at engine operational speed similar to those experienced in flight. Force components at the blade tip in axial and circumferential directions for a rub of moderate incursion depth (140μm) are compared to those for a severe rub (406μm). Similar general trends of variation during the metal-to-metal contact are observed. However, in the nearly threefold higher incursion the maximum incurred circumferential load increases significantly, while the maximum incurred axial load increases much less, demonstrating the non-linear nature of the rub phenomena. Concurrently, the stress magnification on the rubbing blade at root mid-chord, at tip leading edge, and at tip trailing edge is discussed. The results point to the possibility of failure occurring first at the airfoil trailing edge. Such a failure was in fact observed in the most severe rub obtained to date in the laboratory, consistent with field observations. Computational models to analyze the non-linear dynamic response of a rotating beam with periodic pulse loading at the free-end are currently under development and are noted.

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