NIST TRACEABLE PROBE CALIBRATION
Probe Aerodynamic Calibration
Accuracy is Key
An accurate probe aerodynamic calibration is critical to multi-hole probe measurements. The relationship between the measured port pressures and the velocity vector, total pressure, and static pressure of the flow is defined by aerodynamic calibration.
Aeroprobe aerodynamic probe calibrations are performed on-site by highly-trained expert staff to produce the most accurate calibrations in the industry.
The Probe Calibration Process
To aerodynamically calibrate a multi-hole probe, the probe is first placed in one of Aeroprobe’s free-jet wind tunnel facilities where the flow speed and direction are known. The probe is then rotated to several thousand discrete orientations relative to the jet, while maintaining a fixed probe tip position. Finally, the mean pressure measured at each of the probe tip ports is recorded at each discrete orientation and correlated with reference total and static pressure measurements.
Results that Matter
The data set collected during the calibration forms a calibration map, which compensates for manufacturing variations. The calibration map is designed for use with Aeroflow, Aeroprobe’s data reduction software. Aeroflow applies the probe calibrations to test data to compute the following:
- Velocity vector components
- Total and static presssure
- Mach number
Importance of Recalibration
Aerodynamic recalibration is essential to the maintenance of a multi-hole probe. Over the course of time, slight changes to the geometry of the probe tip can occur from handling, use, and/or the accumulation of residue from the flow. These small changes will affect the pressure distribution on the surface of the probe. Consequently, a new calibration is necessary to return the accuracy of the multi-hole probe back to its original specifications.
When to Recalibrate?
Regular probe recalibration will ensure continued measurement reliability. For that reason, Aeroprobe recommends probe recalibration every 12 to 24 months, depending on use.
NIST Traceable Calibrations
What is NIST?
National Institute of Standards and Technology (NIST) is a non-regulatory federal agency under the Department of Commerce. NIST is the United States National Measurement Institute.
What is NIST Traceable?
Probe aerodynamic calibrations are traceable through an unbroken chain of instrument calibrations through the National Institute of Science and Technology.
Returning multi-hole probes for recalibration will ensure that they are NIST traceable after use. However, in order to receive this certification, the probes must be returned to Aeroprobe for calibration.
- Calibration speeds from 5 m/s to mach 2.0
- Angle uncertainty* less than 1°
- Velocity Uncertainty* less than 1 m/s
- Certification documents available upon request
- Custom calibration grids available upon request
*Based on 2σ confidence interval. Assumes Aeroflow 2.0 reduction algorithm used. Excludes contribution from test specific pressure sensor error.