LARGE-SCALE LAMINAR FLOW TESTS EVALUATED WITH LINEAR STABILITY THEORY

A short overview of the different ways to apply linear stability theory in the form of the ^-method for transition prediction in boundary layer flow is given. The ATTAS/VFW614, the Fokker F100, and the Airbus A320 flight tests are evaluated and compared to two hybrid-laminar-flow tests in the SI MA tunnel. N- factor correlations are given for all five tests. It is shown that for hybrid laminar flow transition prediction based on two N-factors, one to model the cross-flow instability and a second one for TollmienSchlichting instability, is superior to the envelope method. Results concerning the influence of surface roughness on the cross-flow instability are discussed. Furthermore, the evaluation shows that in hybrid laminar flow the internal noise coming from the suction system cannot be neglected for the Tollmien-Schlichting amplification.

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