Ultra-low-speed anemometer calibrations in a bench-top wind tunnel

Published

May 20, 2026

Author(s)

Christopher Crowley, Jeyadave Kumar, Iosif Shinder

Abstract

Accurate calibration of anemometers at ultra-low airspeeds (i.e. speeds below 1 m/s) is essential for applications such as indoor airflow measurement, cleanroom monitoring, and environmental sensing. To address this need, the National Institute of Standards and Technology has modified a bench-top wind tunnel to produce stable flows in the range of less than 0.1 m/s to 5 m/s and to support optical and image-based measurement techniques. The test section of the tunnel measures approximately 15 cm × 15 cm, and typical anemometers may occupy up to 5 % of this cross-sectional area. While a compact wind tunnel offers advantages in achieving and controlling low-speed flows, it also presents unique challenges. Chief among these are the blockage effects introduced by the sensor itself and the influence of nearby tunnel walls, both of which can significantly distort the local flow field and reduce calibration accuracy. This work discusses mitigation strategies including blockage correction methods and tunnel design considerations. Numerical simulations indicate that the effects of both sensor and wall blockage can be quantified and largely corrected. Preliminary experimental results support the simulation findings, though further refinements to the tunnel design are needed to fully validate and implement the corrections.

Proceedings Title

The 20th International Flow Measurement Conference

Conference Dates

May 17-20, 2026

Conference Location

Nara, JP

Conference Title

FLOMEKO 2026

Pub Type

Conferences

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Keywords

Blockage effect, anemometer calibration, bench-top wind tunnel, low-speed anemometry

Citation

Crowley, C. , Kumar, J. and Shinder, I. (2026), Ultra-low-speed anemometer calibrations in a bench-top wind tunnel, The 20th International Flow Measurement Conference, Nara, JP, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961618 (Accessed May 28, 2026)

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