Newsletter  2014.1  Index

Theme : "The Conference of Fluid Engineering Division" Preface M.Oshima, Y. Takahashi, H. Yoshikawa Development of coaxial electromagnetic energy conversion device for efficient wind energy utilization Akira TANIDA, Hidemasa TAKANA (Tohoku University) Augmentation and attenuation of large-scale intermittent structures in rotating channel flow Takahiro ISHIDA (Tokyo University of Science) An attempt to measure wall shear stress fluctuation in a turbulent wall jet Takuya SAWADA, Osamu TERASHIMA, Yasuhiko SAKAI, Kouji NAGATA, Mitsuhiro SHIKIDA, Yasumasa ITO (Nagoya University) Concentration statistics near the turbulent / non-turbulent interface of a planar liquid jet with a chemical reaction Takahiro NAITO, Tomoaki WATANABE, Yasuhiko SAKAI, Kouji NAGATA, Yasumasa ITO, Osamu TERASHIMA (Nagoya University) The valuable experience of the Dreams of Flow Contest Tsubasa OZAKI, Jumpei OHKUBO, Hiroaki KOBAYASHI, Kodai FUJITA (Hokkaido University) A story of creation for Dreams of Flow Contest Kodai FUJITA, Hiroaki KOBAYASHI (Hokkaido University)   |  Back  |

 

An attempt to measure wall shear stress fluctuation in a turbulent wall jet

Takuya SAWADA Osamu TERASHIMA Yasuhiko SAKAI Kouji NAGATA Mitsuhiro SHIKIDA Yasumasa ITO Nagoya University

Abstract

The objective of this study is to establish a technique for accurately measuring the wall shear stress in turbulent flows using a micro-fabricated hot-film sensor. In this study, micro-scale hot-film sensor, “Silicon hot-film sensor”, to measure wall shear stress fluctuation is fabricated. Silicon hot-film sensor has a 1 mm-thick silicon wafer, which is realized via an alkali etching process, as its substrate to reduce heat capacity of the substrate, whereas previous hot-film sensor has a 25 mm-thick polyimide film and 0.5 mm-thick silicone rubber film as the substrate. Calibration result in a turbulent wall jet by means of the Preston tube shows that the sensor can measure the time-averaged wall shear stress as expected. In addition, the result of the frequency response test with the sinusoidal wave heat current shows that the frequency response of the Silicon hot-film sensor is 1,000 Hz, whereas that of the previous hot-film sensor is 7 Hz.

 

Key words

Wall shear stress fluctuation, Turbulent wall jet, Micro-fabricated sensor, Hot-film sensor

 

Figures

Fig.1 Schematic view and photograph of the heated element of Silicon hot-film sensor

Fig.2 Calibration result of the Silicon hot-film sensor in a turbulent wall jet

Fig.3 Frequency response of the Silicon hot-film sensor