Analytical and experimental studies on natural laminar flow nacelles

Younghans, James L.; Lahti, D. J.

doi:10.2514/6.1984-34

Cited by 10 publications

(2 citation statements)

References 2 publications

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“…[4][5][6] In many ways, the problem of the sustainment of laminar flow over an engine nacelle is much less restrictive than the equivalent investigations on aircraft wings, as lift generation is not the primary function. Early analytical studies on the effectiveness of a natural laminar flow nacelle [7][8][9][10] indicated that a potential drag reduction of up to 2% of total aircraft drag could be achieved, without incurring a weight penalty, solely by maintaining laminar flow on an engine nacelle. This was reinforced in the NASA study by Obara 11 who indicated that the percentage drag reduction on a typical business jet configuration could be increased from 12 to 24% by extending laminar flow over all aircraft surfaces, rather than limiting efforts to the wing alone.…”

Section: A Backgroundmentioning

confidence: 99%

Influence of Surface Waviness for Laminar Flow Nacelle Applications

Medina¹,

Early²,

Riordan

2009

27th AIAA Applied Aerodynamics Conference

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Transition onset over an engine nacelle is influenced by a large number of factors (for instance, surface roughness, steps, gaps and damage), many of which can be introduced as a result of the manufacturing process. Rivetting processes can lead to the introduction of surface deviations, which can be represented as either a bump or depression wave function. Previous work on the influence of leading edge roughness has demonstrated that such surface deviations can either promote or delay transition onset. The current work at Queen's University Belfast seeks to conduct a comprehensive investigation into the consequences of a depression-type surface irregularity on the transitional characteristics exhibited by a laminar flow nacelle, with specific attention paid to both the depression amplitude and streamwise location. Intial work has indicated that careful positioning of the streamwise location of the depression relative to the leading edge is critical in the selection of appropriate manufacturing tolerances, as even milliscale depressions, which have no appreciable influence on the transitional characteristics of the boundary layer, can have a significant affect on the downstream growth of the turbulent boundary layer. There is also some evidence to suggest that small depressions placed close to the leading edge can have a stabilising effect on the laminar boundary layer, leading to a delay in the transitional Reynolds number in a manner similar to that observed for subcritical protrusions.

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Section: A Backgroundmentioning

confidence: 99%

Influence of Surface Waviness for Laminar Flow Nacelle Applications

Medina¹,

Early²,

Riordan

2009

27th AIAA Applied Aerodynamics Conference

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show abstract

“…The greater part of past research into laminar flow technology has been aimed at aircraft wing surfaces; only recently has attention been turned to other surfaces such as fins and nacelles. The concept of a Natural Laminar Flow (NLF) nacelle shaped to produce a favourable pressure gradient over much of its surface, and hence to maintain laminar stability, was investigated by Younghans and Lahti for General Electric [2] in windtunnel tests. A similar nacelle concept was tested by Barber et al [3] for Pratt and Whitney.…”

Section: Introductionmentioning

confidence: 99%

The Flight Testing of Natural and Hybrid Laminar Flow Nacelles

Barry

Parke

Bown

et al. 1994

Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery

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The achievement of large areas of laminar flow over aircraft engine nacelles offers significant savings in aircraft fuel consumption. Based upon current engine configurations nett sfc benefits of up to 2% are possible. In addition the engine nacelle is ideally suited to the early inclusion of laminar flow technology, being relatively self contained with the possibility of application to existing airframes. In September 1992 a European Consortium managed by Rolls-Royce including MTU and DLR began flight testing of a natural laminar flow nacelle. This programme was later extended by R-R and DLR to flight test a hybrid laminar flow nacelle featuring boundary layer suction and insect contamination protection. The tests evaluated the effects of flight and engine environment, boundary layer transition phenomena, suction system operation and insect contamination avoidance strategies. This paper describes the global conclusions from these flight tests which are a significant milestone leading to the future application of laminar flow technology to engine nacelles.

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Adaptive-surrogate-based robust optimization of transonic natural laminar flow nacelle

Yao

Yang

et al. 2021

Chinese Journal of Aeronautics

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Analytical and experimental studies on natural laminar flow nacelles

Cited by 10 publications

References 2 publications

Influence of Surface Waviness for Laminar Flow Nacelle Applications

Influence of Surface Waviness for Laminar Flow Nacelle Applications

The Flight Testing of Natural and Hybrid Laminar Flow Nacelles

Adaptive-surrogate-based robust optimization of transonic natural laminar flow nacelle

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