Relaminarization on swept leading edges under high-lift conditions

Viswanath, PR and Mukund, R and Narasimha, R and Crouch, JD (2006) Relaminarization on swept leading edges under high-lift conditions. AIAA Journal, 44 (11). pp. 2621-2629. ISSN 0001-1452

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Abstract

Detailed experiments were made to gain an improved understanding of relaminarization on swept wings under high-lift conditions. Two swept wings with different airfoil sections and flaps were tested, and measurements were made consisting of surface-pressure distributions13; and wall shear-stress fluctuations in the leading-edge zone. Measurements were made at a chord Reynolds number of 1.3 x 106 with wing-sweep angles of 45 and 60 deg and model incidence varied in the range of 3 to 18 deg in discrete steps. Following the attachment-line transition, the turbulent boundary layer relaminarized under certain13; conditions due to the acceleration around the wing's leading edge. Broad features of relaminarization and subsequent retransition are discussed based on wall shear-stressfluctuation data. The present dataset shows that relaminarization is likely if the maximum value of13; the acceleration parameter K, (evaluated along the external inviscid streamline) is greater than about 3 x 10-6, in agreement with earlier findings. Much higher maximum values of IC, result in significant reduction of intermittency during relaminarization. After relaminarization, the boundary layer retransitions across a separation bubble. Characteristics of the post relaminarization separation bubbles are shown to be similar to those of bubbles occurring in more pristine13; laminar boundary layers.

Item Type: Journal Article
Uncontrolled Keywords: Bubbles;Swept wings;Acceleration;Walls;Separation;Leading edges;Airfoils;Reduction;Turbulent flow;Reynolds number; Fluid flow;Laminar boundary layer;Mathematical models;Aircraft components;Flaps;Turbulent boundary layer;Incidence;Gain
Subjects: AERONAUTICS > Aeronautics (General)
Division/Department: National Trisonic Aerodynamic Facility, Experimental Aerodynamics Division, Other, Other
Depositing User: M/S ICAST NAL
Date Deposited: 17 Jan 2008
Last Modified: 24 May 2010 09:55
URI: http://nal-ir.nal.res.in/id/eprint/4304

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