Hot-wire probes use thin tungsten wires heated to a fixed temperature to measure velocity and temperature gradients in turbulent thermal boundary layers. The student developed a LabVIEW program to automate data collection from hot-wire probes in a wind tunnel to obtain more accurate readings of velocity, temperature, and density fluctuations without manual operation. Graphs of probe measurements show turbulent fluctuations at different temperatures.

1. National Aeronautics and Space Administration
www.nasa.gov
Measurement of Turbulent Fluctuations in Thermal Boundary Layers
Using Hot-wire Probes
Gautham Viswaroopan Mentor: Dr. Jayanta Panda
University of Colorado Boulder Experimental Aero-physics
Hot-wire Probes:
• measure the velocity and temperature
gradients
• consists of a 1 micrometer diameter
Tungsten wire heated to a fixed
temperature
• Temperature change is monitored to
measure air velocity and temperature
LabVIEW
Front Panel Block Diagram
Measurements of turbulent
fluctuations in different flow
settings are difficult using current
experimental techniques. Velocity
is important but temperature and
density readings and accuracy are
important as well! This Rayleigh
scattering-based technique to
measure velocity, temperature,
and density in wind tunnel
applications will provide more
accurate readings and will provide
further use for larger applications.
LabVIEW was utilized to make the Thor Labjack
automated to get consistent readings without having to
manually hit jog. The programs were set that every time
I hit run, the jack increased by a given value for an input
amount of readings.
Lab
Setup
Graphic Results
Different tests at different temperatures taken
by the hot-wire probes
Image of a Hot-wire probe from Fluid Mechanics Lab
Hot
Plate
Introduction and
Problem