Laminar-Turbulent Intermittency Measurement Based on the Uncalibrated Hot-Film Data

Abstract A new technique for the laminar-turbulent intermittency measurement based on the surface hot-film data is presented. The existing techniques require data acquired from the calibrated hot-films which leads to the real wall shear stress values. However, calibration of the hot-films is usually very complex. In the proposed method, a technique based on the probability distribution function (PDF) of the acquired data using the uncalibrated hot-film sensors is presented and evaluated. The PDF is prepared for a reduced form of the quasi-wall shear stress value instead of the real shear stress value one. This leads to a standard normal distribution curve for the PDF in the turbulent flow region and used as an identifier for the turbulent boundary layer detection. This identifier is employed to calculate the intermittency from the output signal of the hot-film. The sensitivity analyses for the present technique along with a detailed discussion of the results are presented. Following a complete review of the previous techniques, the importance, impact, and applicability of the current method are stated.