Title :
Skin friction measurement in variable temperature flow
Author :
Shen, C. ; Song, T. ; Lemmin, U.
Author_Institution :
LRH-DGC-EPFL, Lausanne, Switzerland
Abstract :
A new skin friction sensor with constant sensitivity in variable temperature flow has been developed. It is based on a specially designed temperature compensation bridge which contains two sub-bridges for flow and temperature sensors. In our case identical hot film elements (active surface 1.5 mm×2.5 mm), one operating as a hot film (skin friction) and one as a cold film (temperature) were mounted side by side on a small plate. Calibration shows the good performance of the system when the water temperature varies in a wide range and with strong temperature gradients. When the friction velocity u* meets condition L´ 2Pr>200 and L´<64Pr, good linearity between u*1/2 and the output of the probe E2 is obtained. In addition, for the case when u* is very high, a relationship based on calibration is presented
Keywords :
bridge circuits; calibration; compensation; electric sensing devices; flow measurement; friction; pipe flow; stress measurement; temperature measurement; temperature sensors; water; 1.5 mm; 2.5 mm; H2O; active surface; calibration; cold film; constant sensitivity; flow and temperature sensors; friction velocity; hot film; hot film elements; linearity; skin friction; skin friction measurement; skin friction sensor; sub-bridges; temperature compensation bridge; temperature gradients; temperature sensors; variable temperature flow; water temperature; Bridges; Calibration; Fluid flow measurement; Friction; Linearity; Probes; Skin; Temperature distribution; Temperature measurement; Temperature sensors;
Conference_Titel :
Instrumentation and Measurement Technology Conference, 1996. IMTC-96. Conference Proceedings. Quality Measurements: The Indispensable Bridge between Theory and Reality., IEEE
Conference_Location :
Brussels
Print_ISBN :
0-7803-3312-8
DOI :
10.1109/IMTC.1996.507437
