Temperature-Compensated Calibration and Measurements with Cross-Style Hotwire Anemometers
Abstract
Flow field measurements collected using constant-temperature hotwire anemometers (CTAs) are known to be sensitive to variation in the ambient fluid temperature. Various calibration techniques are detailed in literature for temperature compensation of single-component velocity measurements using single-normal hotwires. However, a rigorous methodology has not yet been defined for temperature compensation in two-component velocity measurements using cross-style hotwires. This research defines a procedure for the calibration of cross-style hotwires from which temperature compensated estimates of the streamwise, U, and spanwise, W, components of the local velocity are obtained. To map the effects of ambient temperature, flow angularity, and velocity magnitude to hotwire voltages, a series of four calibration sweeps is conducted at the beginning of each day of operation. Resulting velocity component accuracy is analyzed for several known flow angle, temperature, and velocity magnitude combinations in the freestream. Based on the study’s results, model form errors in the hotwire responses are known a priori for general experiments to remain under 2% for measurements taken within the bounds of the calibration probe angle range while component uncertainties are determined for the included experiment a posteriori to range up to ±1.1% of the measured velocity magnitude and within ±0.6° of the measured flow angle. Comparisons of cross-style and single-normal hotwire flat-plate boundary layer measurements in the wake of a vortex generator demonstrate excellent agreement in the streamwise component estimates.
Subject
Wind Tunnel TestingMeasurement Techniques
Hotwire Anemometry
Cross-style Hotwires
Temperature Compensation
Citation
Finke, Colton Phillip (2021). Temperature-Compensated Calibration and Measurements with Cross-Style Hotwire Anemometers. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /196256.