Simplified Hybrid Laminar Flow Control for the A320 Fin - Aerodynamic and System Design, First Results

Schrauf, G.; Geyr, H. von

doi:10.2514/6.2020-1536

Cited by 31 publications

(30 citation statements)

References 3 publications

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“…To obtain reference skin-friction values in the laminarflow region, compressible boundary-layer calculations were carried out using the laminar boundary-layer solver COCO (Schrauf 1998), which is a well established code for boundary-layer stability analysis and laminar wing design (see Streit et al (2015) and Schrauf and von Geyr (2020), among others). The surface pressure distributions, measured by means of the pressure taps, served as inputs for the boundary-layer computations, together with the freestream Mach number, the chord Reynolds number, and the freestream static temperature.…”

Section: Discussion Of the Glofsfe Estimations In The Laminar-flow Rementioning

confidence: 99%

Feasibility of skin-friction field measurements in a transonic wind tunnel using a global luminescent oil film

et al. 2021

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The feasibility of skin-friction field measurements using the global luminescent oil-film skin-friction field estimation method was evaluated for a challenging case of a supercritical airfoil model under transonic wind-tunnel conditions (freestream Mach number of 0.72) at a high Reynolds number (10 million, based on the model chord length). The oil-film thickness and skin-friction coefficient distributions were estimated over the airfoil model upper surface for a range of angles of attack (from $$-0.4^{\circ }$$ - 0 . 4 ∘ to $$2.0^{\circ }$$ 2 . 0 ∘ ), thus enabling the study of different boundary-layer stability situations with laminar–turbulent transition, including cases with shock-wave/boundary-layer interaction. Conventional pressure measurements on the surface and in the wake of the model as well as Schlieren flow visualizations were conducted to support the oil-film based investigations. In the laminar-flow regions, the oil-film thickness could be generally kept below the critical limit of roughness that would induce premature boundary-layer transition. The skin friction in this region could be estimated with a moderate confidence level, as confirmed for portions of the chord by the reasonable agreement with numerical data obtained via laminar boundary-layer computations. Moreover, the location of transition onset was evaluated from the skin-friction estimations with relatively low uncertainty, thus enabling the examination of the transition location evolution with varying angle of attack. The estimated locations of transition onset were shown to be in general agreement with reference transition locations measured via temperature-sensitive paint. On the other hand, the oil-film thickness in the turbulent-flow regions was larger than the height of the viscous sublayer, which led to an hydraulically rough surface with increased skin friction, as compared to the clean configuration. For this reason, quantitative skin-friction estimations were not feasible in the turbulent-flow regions. The global effects of the oil-film setup on the flow around the airfoil were evaluated from the estimations of the aerodynamic coefficients. In particular, it was shown that the presence of the specific base coat used for the application of the oil film already induced a significant increase in airfoil drag, as compared to the clean configuration, whereas a thin oil film led to negligible or small additional increases in drag. Based on the present observations, considerations for the further improvement of the global luminescent oil-film skin-friction field estimation method in transonic flow experiments at high Reynolds numbers are elucidated. Graphic abstract

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Section: Discussion Of the Glofsfe Estimations In The Laminar-flow Rementioning

confidence: 99%

Feasibility of skin-friction field measurements in a transonic wind tunnel using a global luminescent oil film

et al. 2021

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“…A promising approach for simultaneously addressing all critical instability mechanisms is hybrid laminar flow control (HLFC); this technique combines the shaping of the airfoil in the mid-chord region (natural laminar flow, NLF) with the application of active suction ahead of the front spar (laminar flow control, LFC) [15]. Most recently, the potential of a simplified HLFC system on the vertical tailplane of an Airbus A320 was demonstrated in a flight test [30].…”

Section: Fundamentalsmentioning

confidence: 99%

HLFC-optimized retrofit aircraft design of a medium-range reference configuration within the AVACON project

2021

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This paper presents an approach for the design of a retrofit aircraft with integrated, optimized hybrid laminar flow control (HLFC). The basis for this research is a medium-range reference configuration derived within the German LuFo project “Advanced Aircraft Concepts” (AVACON). For the aerodynamics, an in-house-developed process chain for flow analysis is used, which requires airfoil shapes at specific sections of a known wing geometry. To improve the accuracy, pressure distributions from the 2D flow solver MSES are first aligned to high-fidelity 3D results from DLR’s TAU code for extracted airfoils. This is done by varying parameters of the transformation methods used. Subsequently, the required suction distributions are optimized based on pre-defined criteria; these include not only the aerodynamic effects but also the needed mass flows. After optimizing the HLFC system architecture concerning mass and power offtakes, a retrofit aircraft is designed with the in-house “Multidisciplinary Integrated Aircraft Design and Optimization” (MICADO) environment. Compared to the turbulent baseline, the promising potential of the HLFC technology is demonstrated. In addition, the actual benefit of the optimization approach is evaluated in the context of overall preliminary aircraft design. This is done by redesigning the aircraft with other suction distributions and HLFC system architectures. Although it is shown that the approach leads to an overall optimum, the optimization benefit remains small. This indicates the limits of the HLFC technology as a pure add-on for initially turbulent aircraft and the need for the application of new laminar wing design methods to tap the full potential of HLFC.

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“…This has allowed us to separate the system design from the development of the capabilities of the manufacturer. The final values of the coefficients are = 12400 /( 2 ) and = 18270 / 3 [6]. By inverting formula (1), we obtain the suction velocity .…”

Section: Suction Distributionmentioning

confidence: 99%

“…Nevertheless, it has been used for HLFC-design, as for example the design pf the DNW-LLF test (cf. Figure 2 in [6], for the design of this HLFC system, and for current projects.…”

Section: -Factor Correlationmentioning

confidence: 99%

“…The next step was a flight test demonstration within the European AFLoNext project based on a simplified HLFC system installed in the VTP of an A320 aircraft shown in Figure 2. The aerodynamic and systems design of the HLFC leading edge was described in our previous paper [6]. Now we will report on the flights tests and their evaluation with linear stability theory.…”

Section: Introductionmentioning

confidence: 99%

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Simplified Hybrid Laminar Flow Control for the A320 Fin. Part 2: Evaluation with the e^N-method

Schrauf

Geyr

2021

AIAA Scitech 2021 Forum

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Simplified Hybrid Laminar Flow Control for the A320 Fin - Aerodynamic and System Design, First Results

Cited by 31 publications

References 3 publications

Feasibility of skin-friction field measurements in a transonic wind tunnel using a global luminescent oil film

Feasibility of skin-friction field measurements in a transonic wind tunnel using a global luminescent oil film

HLFC-optimized retrofit aircraft design of a medium-range reference configuration within the AVACON project

Simplified Hybrid Laminar Flow Control for the A320 Fin. Part 2: Evaluation with the e^N-method

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Simplified Hybrid Laminar Flow Control for the A320 Fin - Aerodynamic and System Design, First Results

Cited by 31 publications

References 3 publications

Feasibility of skin-friction field measurements in a transonic wind tunnel using a global luminescent oil film

Feasibility of skin-friction field measurements in a transonic wind tunnel using a global luminescent oil film

HLFC-optimized retrofit aircraft design of a medium-range reference configuration within the AVACON project

Simplified Hybrid Laminar Flow Control for the A320 Fin. Part 2: Evaluation with the eN-method

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Simplified Hybrid Laminar Flow Control for the A320 Fin. Part 2: Evaluation with the e^N-method