TY - JOUR
T1 - Photoacoustic hygrometer for icing wind tunnel water content measurement
T2 - Design, analysis, and intercomparison
AU - Lang, Benjamin
AU - Breitfuss, Wolfgang
AU - Schweighart, Simon
AU - Breitegger, Philipp
AU - Pervier, Hugo
AU - Tramposch, Andreas
AU - Klug, Andreas
AU - Hassler, Wolfgang
AU - Bergmann, Alexander
N1 - Funding Information:
Financial support. This work has been partly funded by the Austrian Aeronautics Programme TAKE OFF of the Federal Ministry of Transport, Innovation and Technology (BMVIT), managed by the Österreichische Forschungsförderungsgesellschaft (FFG; Project number: 850457).
Publisher Copyright:
© 2021 Copernicus GmbH. All rights reserved.
PY - 2021/3/31
Y1 - 2021/3/31
N2 - This work describes the latest design, calibration and application of a near-infrared laser diode-based photoacoustic (PA) hygrometer developed for total water content measurement in simulated atmospheric freezing precipitation and high ice water content conditions with relevance in fundamental icing research, aviation testing, and certification. The single-wavelength and single-pass PA absorption cell is calibrated for molar water vapor fractions with a two-pressure humidity generator integrated into the instrument. Laboratory calibration showed an estimated measurement accuracy better than 3.3%in the water vapor mole fraction range of 510-12 360 ppm (5% from 250-21 200 ppm) with a theoretical limit of detection (3δ) of 3.2 ppm. The hygrometer is examined in combination with a basic isokinetic evaporator probe (IKP) and sampling system designed for icing wind tunnel applications, for which a general description of total condensed water content (CWC) measurements and uncertainties are presented. Despite the current limitation of the IKP to a hydrometeor mass flux below 90 gm-2s-1, a CWC measurement accuracy better than 20% is achieved by the instrument above a CWC of 0.14 gm-3in cold air (-30°C) with suitable background humidity measurement. Results of a comparison to the Cranfield University IKP instrument in freezing drizzle and rain show a CWC agreement of the two instruments within 20 %, which demonstrates the potential of PA hygrometers for water content measurement in atmospheric icing conditions.
AB - This work describes the latest design, calibration and application of a near-infrared laser diode-based photoacoustic (PA) hygrometer developed for total water content measurement in simulated atmospheric freezing precipitation and high ice water content conditions with relevance in fundamental icing research, aviation testing, and certification. The single-wavelength and single-pass PA absorption cell is calibrated for molar water vapor fractions with a two-pressure humidity generator integrated into the instrument. Laboratory calibration showed an estimated measurement accuracy better than 3.3%in the water vapor mole fraction range of 510-12 360 ppm (5% from 250-21 200 ppm) with a theoretical limit of detection (3δ) of 3.2 ppm. The hygrometer is examined in combination with a basic isokinetic evaporator probe (IKP) and sampling system designed for icing wind tunnel applications, for which a general description of total condensed water content (CWC) measurements and uncertainties are presented. Despite the current limitation of the IKP to a hydrometeor mass flux below 90 gm-2s-1, a CWC measurement accuracy better than 20% is achieved by the instrument above a CWC of 0.14 gm-3in cold air (-30°C) with suitable background humidity measurement. Results of a comparison to the Cranfield University IKP instrument in freezing drizzle and rain show a CWC agreement of the two instruments within 20 %, which demonstrates the potential of PA hygrometers for water content measurement in atmospheric icing conditions.
UR - http://www.scopus.com/inward/record.url?scp=85103620803&partnerID=8YFLogxK
U2 - 10.5194/amt-14-2477-2021
DO - 10.5194/amt-14-2477-2021
M3 - Article
AN - SCOPUS:85103620803
SN - 1867-1381
VL - 14
SP - 2477
EP - 2500
JO - Atmospheric Measurement Techniques
JF - Atmospheric Measurement Techniques
IS - 3
ER -