Open AccessAn innovative flow-measuring device - Thermocouple boundary layer rake
Author(s) -
Danny P. Hwang,
Gustave C. Fralick,
Lisa C. Martin,
John D. Wrbanek,
Charles Blaha
Publication year - 2002
Publication title -
nasa technical reports server (nasa)
Language(s) - English
Resource type - Conference proceedings
DOI - 10.2514/6.2002-289
Subject(s) - thermocouple , materials science , boundary layer , flow (mathematics) , rake , temperature measurement , layer (electronics) , computer science , mechanical engineering , mechanics , composite material , engineering , physics , quantum mechanics
An innovative flow-measuring device, a thermocoupleboundary layer rake, was developed. The sensor detectsthe flow by using a thin-film thermocouple (TC) array tomeasure the temperature difference across a heater strip.The heater and TC arrays are microfabricated on a constant-thickness quartz strut with low heat conductivity. Thedevice can measure the velocity profile well into theboundary layer, about 65 µm from the surface, which isalmost four times closer to the surface than has beenpossible with the previously used total pressure tube. SYMBOLS c chord lengthp static pressurep 1 static pressure on streamline ahead of strutRe Reynolds number based on strut lengthU axial velocity, m/secU + U/u τ u τ frictional velocity, τρ ww ∆V voltage differentialU ∞ velocity at edge of boundary layerx axial distance from leading edge of sensor struty coordinate of measurement from surface, cmy + yu τ /ν w θ momentum thicknessν w kinematic viscosity on wallρ w density on wallτ w shear stress on wall
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