On Transition Detection at High Subsonic Freestream Mach Numbers Using Thermoresistive Surface Sensors

Leuckert, Janin; Erdmann, Ralf; Nitsche, W.; Rosemann, Henning

doi:10.2514/6.2011-879

Cited by 3 publications

(1 citation statement)

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“…Since the first investigations by Liepmann and Skinner (1954) and Bellhouse and Schultz (1966), surface mounted hot-film sensors have become an established measurement technique for measuring wall shear stresses. The application of multiple hot-film sensor (MHFS) arrays for the largescale investigation of the boundary layer of bodies in flows is common as well and, due to the high dynamic response of the measurement technique, particularly suitable for the more precise characterization of instability mechanisms in boundary layers as it was done by Leuckert et al (2011), for example. Lee and Basu (1998) used MHFS to study the unsteady development of the boundary layer on an oscillating airfoil model at low Reynolds numbers.…”

Section: Introductionmentioning

confidence: 99%

Application of hot-film anemometry to resolve the unsteady boundary layer transition of a laminar airfoil experiencing limit cycle oscillations

Braune

Koch

2020

Exp Fluids

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The unsteady boundary layer behavior of a supercritical laminar airfoil model, which undergoes limit cycle oscillations in pitch, is investigated by the application of hot-film anemometry. The data basis is a 2D flutter experiment under transonic flow conditions. The laminar airfoil model was elastically mounted with a single degree of freedom in pitch and performed self-excited limit cycle oscillations at a Mach number of Ma = 0.73 and a Reynolds number of Re ≈ 2 × 10 6. An analysis of the hot-film signals on the basis of the quasi-wall shear stress is carried out, with which the boundary layer state for steady and unsteady flow is resolved. An algorithm is presented which allows an automated detection of the transition position, so that a correlation between airfoil motion and transition location movement can be quantified. A sudden movement of the boundary layer transition is observed at the upper and lower reversal points of the limit cycle oscillation, while in parts of the up-and downstroke of the laminar airfoil a shock-induced transition occurs. During the limit cycle oscillation, a delayed response of the boundary layer occurs, resulting in a significant phase lag between the movement of the boundary layer transition and the motion of the laminar airfoil. List of symbols A Constant a Overheat ratio Mean angle of attack (•) Pitch amplitude, pitch motion (•) B Constant c Chord length (m) c d Drag coefficient c l Lift coefficient c m Pitching moment coefficient c p Pressure coefficient c * p

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Section: Introductionmentioning

confidence: 99%