| Summary: | LDV (Laser Doppler Velocimetry) measurement has been made in the high Reynolds number (1010≦Re τ≦20700) turbulent pipe flow to clarify its mean flow quantity. The accuracy of the mean velocity in LDV measurement was checked by a comparison between the integration of the mean velocity profile and the actual flow rate measured by a weighting system in AIST (Advanced Industrial Science and Technology), NMIJ (National Metrology Institute of Japan). Near wall measurement is achieved by evaluating accurately the effect of refraction at the pipe wall and the actual center of measurement volume. Mean velocity profiles are compared with functional forms in the overlap region proposed by previous studies (such as, Barrenblatt, Afzal, Wosnik, et al. and McKeon, et al.). As a result, the regions which satisfy power law or log law are consistent with the one suggested by Zagarola&Smits and McKeon, et al. However, the constants are γ = 0.143, C = 8.61, κ = 0.389 and B = 4.83, respectively, and are different from values proposed by McKeon et al. Especially in log law, the present data satisfies Wosnik's formula including the mesolayer. We assume that the differences of log low and power law coefficients from the previous result may be affected by some factors, such as differences of friction coefficient, velocimetry method, working fluid and pressure operation.
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