Acoustic Liner Drag: A Parametric Study of Conventional Configurations

Howerton, Brian M.; Jones, Michael G.

doi:10.2514/6.2015-2230

Cited by 17 publications

(17 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…79. Thus ourCFD study suggests that the simple equation(2) overestimates the absolute skin friction ratio the skin-friction penalty…”

mentioning

confidence: 65%

“…Our CFD study, based on conventional RANS turbulence modeling, of the NASA Langley Grazing Flow Impedance Tube appears conclusive, and to provide quantitative information. The principal conclusion is that the simple equation (2) which has been used to deduce the skin friction from the pressure drop overestimates the skinfriction absolute value by about 25% and the relative penalty (  L /  SW -1 ) by nearly 90%, which is significant enough to be taken into account. This is due to both the sustained inhomogeneity of the flow as the pressure drops and the momentum flux steadily increases, which the formula ignored, and to transient effects as the effective roughness is imposed, and then removed.…”

Section: Discussionmentioning

confidence: 99%

“…he NASA Langley Grazing Flow Impedance Tube (GFIT) is used for creative design and testing of acoustic liners in the presence of grazing flow [1,2]. Recent efforts have added drag measurement capabilities, which have been employed to develop liners that appear to suppress their typical skin-friction penalty.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

CFD Analysis of an Installation Used to Measure the Skin-Friction Penalty of Acoustic Treatments

Spalart

Garbaruk²,

Howerton

2017

23rd AIAA/CEAS Aeroacoustics Conference

Self Cite

View full text Add to dashboard Cite

There is a drive to devise acoustic treatments with reduced skin-friction and therefore fuel-burn penalty for engine nacelles on commercial airplanes [1]. The studies have been experimental, and the effects on skin-friction are deduced from measurements of the pressure drop along a duct. We conduct a detailed CFD analysis of the installation, for two purposes. The first is to predict the effects of the finite size of the rig, including its nearsquare cross-section and the moderate length of the treated patch; this introduces transient and blockage effects, which have not been included so far in the analysis. In addition, the flow is compressible, so that even with homogeneous surface conditions, it is not homogeneous in the streamwise direction. The second purpose is to extract an effective sandgrain roughness size for a particular liner, which in turn can be used in a CFD analysis of the aircraft, leading to actual predictions of the effect of acoustic treatments on fuel burn in service. The study is entirely based on classical turbulence models, with an appropriate modification for effective roughness effects, rather than directly modeling the liners. Nomenclature

show abstract

“…79. Thus ourCFD study suggests that the simple equation(2) overestimates the absolute skin friction ratio the skin-friction penalty…”

mentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

CFD Analysis of an Installation Used to Measure the Skin-Friction Penalty of Acoustic Treatments

Spalart

Garbaruk²,

Howerton

2017

23rd AIAA/CEAS Aeroacoustics Conference

Self Cite

View full text Add to dashboard Cite

show abstract

“…This method can be applied to small ducts with fully-developed, turbulent flow and is similar to Nikuradse's approach when studying roughness in pipes. 5,6 With the static pressure data and selected flow parameters, one can compute the duct resistance factor, λ (also known as the 'friction factor'), given by the following:…”

Section: Liner Drag Measurementsmentioning

confidence: 99%

A Conventional Liner Acoustic/Drag Interaction Benchmark Database

Howerton

Jones

2017

23rd AIAA/CEAS Aeroacoustics Conference

Self Cite

View full text Add to dashboard Cite

“…This facility uses a force balance to measure the drag force directly, from which the drag coefficient is calculated. Another cross-reference that will be used in future analyses is provided by the Grazing Flow Impedance Tube (GFIT) 17 , which is located in the same laboratory as the CDTR. The capability of the GFIT, which like the CDTR was originally intended as an acoustic facility, is being expanded for drag measurement, in this case using the change in static pressure, which is directly proportional to the skin friction drag.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Skin Friction Drag for Liner Applications in Aircraft

Gerhold

Brown

Jasinski

2016

54th AIAA Aerospace Sciences Meeting

View full text Add to dashboard Cite

A parameter that is gaining significance in the evaluation of acoustic liner performance is the skin friction drag induced by air flow over the liner surface. Estimates vary widely regarding the amount of drag the liner induces relative to a smooth wall, from less than a 20% increase to nearly 100%, and parameters such as face sheet perforate hole diameter, percent open area, and sheet thickness are expected to figure prominently in the skin friction drag. Even a small increase in liner drag can impose an economic penalty, and current research is focused on developing 'low drag' liner concepts, with the goal being to approach the skin friction drag of a smooth wall. The issue of skin friction drag takes on greater significance as airframe designers investigate the feasibility of putting sound absorbing liners on the non-lifting surfaces of the wings and fuselage, for the purpose of reducing engine noise reflected and scattered toward observers on the ground. Researchers at the NASA Langley Research Center have embarked on investigations of liner skin friction drag with the aims of: developing a systematic drag measurement capability, establishing the drag of current liners, and developing liners that produce reduced drag without compromising acoustic performance. This paper discusses the experimental procedures that have been developed to calculate the drag coefficient based on the change in momentum thickness and the companion research program being carried out to measure the drag directly using a force balance. Liner samples that are evaluated include a solid wall with known roughness and conventional liners with perforated facesheets of varying hole diameter and percent open area.

show abstract

Acoustic Liner Drag: A Parametric Study of Conventional Configurations

Cited by 17 publications

References 7 publications

CFD Analysis of an Installation Used to Measure the Skin-Friction Penalty of Acoustic Treatments

CFD Analysis of an Installation Used to Measure the Skin-Friction Penalty of Acoustic Treatments

A Conventional Liner Acoustic/Drag Interaction Benchmark Database

Evaluation of Skin Friction Drag for Liner Applications in Aircraft

Contact Info

Product

Resources

About