Title :
A transition detection study at Mach 1.5, 2.0 and 2.5 using a micro-thin hot-film system
Author :
Johnson, Charles B. ; Carraway, Debra L.
Author_Institution :
NASA Langley Res. Center, Hampton, VA, USA
Abstract :
A boundary-layer transition detection study was conducted in the Langley unitary plan wind tunnel with an array of micro-thin hot films on a flat plate at Mach numbers from 1.0 to 4.5 million per foot. Transition locations were obtained online from the variation of normalized RMS (root mean square) voltages from an array of hot-film sensors for both natural transition and a grit-induced wedge of turbulence. The effects of Mach number and Reynolds number on the location and lengths of the transition region for the two types of transition are presented from the online data. Also shown are the unit Reynolds number effects on transition Reynolds number, voltage-versus-time traces, spectra, and the data-acquisition system
Keywords :
boundary layers; computerised instrumentation; laminar to turbulent transitions; wind tunnels; Langley unitary plan wind tunnel; Mach numbers; Reynolds number; boundary-layer transition detection; computerised instrumentation; data-acquisition; flat plate; grit-induced wedge of turbulence; hot-film sensors; micro-thin hot-film system; natural transition; normalized RMS; online data; voltage-versus-time traces; voltages; Foot; Frequency modulation; Infrared sensors; Leg; Liquid crystals; NASA; Optical arrays; Sensor arrays; Testing; Voltage fluctuations;
Conference_Titel :
Instrumentation in Aerospace Simulation Facilities, 1989. ICIASF '89 Record., International Congress on
Conference_Location :
Gottingen
DOI :
10.1109/ICIASF.1989.77661
