Preliminary Results from an Experimental Assessment of a Natural Laminar Flow Design Method

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

“…Lately, a new discussion on the value for the transition -factor to be used with compressible stability theory has arisen in the context of the NASA NLF common research model and the Crossflow-Attenuated NLF design [17][18][19][20]. The question is whether = 10 is adequate when using compressible stability theory.…”

Robust Design of Transonic Natural Laminar Flow Wings under Environmental and Operational Uncertainties

“…The extent of the laminar flow regions strongly depends on the environment [8]. Hence, the robustness of laminar wings against environmental changes, causing instabilities that can unexpectedly trigger transition, and off-design conditions is crucial.…”

Robust Design of Transonic Natural Laminar Flow Wings Under Environmental and Operational Uncertainties

“…These uncertainties will effectively reduce the critical N-Factor used to predict the transition location and transition will be shifted upstream. This problem is present not only in free flight but can also be observed during wind tunnel testing [8]. For example, wind tunnel tests performed at the National Transonic Facility in NASA Langley estimated a critical N-Factor between 4 to 8 for transition caused by TS instabilities [10].…”

“…However, it is possible to obtain pressure profiles that mitigate CF instabilities through shape design without the need for active flow-control devices. An example for the redesign of the NASA Common Research Model can be found in [7,8] applying inverse design techniques.…”

“…Step 3: Iterate The extent of the laminar flow regions strongly depends on the environment [8]. Hence, the robustness of laminar wings against environmental changes, causing instabilities that can unexpectedly trigger transition, and off-design conditions is crucial.…”