Investigations of Laminar to Turbulent Transition in an Oscillating Airfoil Boundary Layer

Ohno, Duncan; Romblad, Jonas; Khaled, Marwan; Rist, Ulrich

doi:10.1007/978-3-030-67902-6_40

Cited by 1 publication

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“…The authors reported noticeable agreement with the transition location highlighted by means of numerical simulations for the same flow case. Beside the optical techniques mentioned above, hot-wire probes and fast response pressure sensors are typically adopted to determine the boundary layer state with single point measurements (e.g., Siddiqui et al (2013), Ohno et al (2022)). Schulte and Hodson (1998) used signals from single hot-wire probe and surface-mounted hot-film gauges to investigate the turbulent patches originated from the wake boundary layer interaction in low-pressure turbine blades.…”

Section: Introductionmentioning

confidence: 99%

A procedure for computing the spot production rate in transitional boundary layers

et al. 2022

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The present work describes a method for the computation of the nucleation rate of turbulent spots in transitional boundary layers from particle image velocimetry (PIV) measurements. Different detection functions for turbulent events recognition were first tested and validated using data from direct numerical simulation, and this latter describes a flat-plate boundary layer under zero pressure gradient. The comparison with a previously defined function adopted in the literature, which is based on the local spanwise wall-shear stress, clearly highlights the possibility of accurately predicting the statistical evolution of transition even when the near-wall velocity field is not directly available from the measurements. The present procedure was systematically applied to PIV data collected in a wall-parallel measuring plane located inside a flat plate boundary layer evolving under variable Reynolds number, adverse pressure gradient (APG) and free-stream turbulence. The results presented in this work show that the present method allows capturing the statistical response of the transition process to the modification of the inlet flow conditions. The location of the maximum spot nucleation is shown to move upstream when increasing all the main flow parameters. Additionally, the transition region becomes shorter for higher Re and APG, whereas the turbulence level variation gives the opposite trend. The effects of the main flow parameters on the coefficients defining the analytic distribution of the nucleation rate and their link to the momentum thickness Reynolds number at the point of transition are discussed in the paper. Graphical abstract

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Section: Introductionmentioning

confidence: 99%