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Isokinetic TWC Evaporator Probe: Calculations and Systemic Uncertainty AnalysisA new Isokinetic Total Water Content Evaporator (IKP2) was downsized from a prototype instrument, specifically to make airborne measurements of hydrometeor total water content (TWC) in deep tropical convective clouds to assess the new ice crystal Appendix D icing envelope. The probe underwent numerous laboratory and wind tunnel investigations to ensure reliable operation under the difficult high altitude/speed/TWC conditions under which other TWC instruments have been known to either fail, or have unknown performance characteristics and the results are presented in a companion paper (Ref. 1). This paper presents the equations used to determine the total water content (TWC) of the sampled atmosphere from the values measured by the IKP2 or necessary ancillary data from other instruments. The uncertainty in the final TWC is determined by propagating the uncertainty in the measured values through the calculations to the final result. Two techniques were used and the results compared. The first is a typical analytical method of propagating uncertainty and the second performs a Monte Carlo simulation. The results are very similar with differences that are insignificant for practical purposes. The uncertainty is between 2 and 3 percent at most practical operating conditions. The capture efficiency of the IKP2 was also examined based on a computational fluid dynamic simulation of the original IKP and scaled down to the IKP2. Particles above 24 micrometers were found to have a capture efficiency greater than 99 percent at all operating conditions.


Document ID
20160013857
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Davison, Craig R.
(National Research Council of Canada Ottawa, Ontario, Canada)
Strapp, John W.
(Met Analytics Aurora, Ontario, Canada)
Lilie, Lyle E.
(Science Engineering Associates, Inc. )
Ratvasky, Thomas P.
(NASA Glenn Research Center Cleveland, OH United States)
Dumont, Christopher
(William J. Hughes Technical Center Atlantic City, NJ, United States)
Date Acquired
November 30, 2016
Publication Date
October 1, 2016
Subject Category
Aerodynamics
Report/Patent Number
NASA/TM-2016-219150
GRC-E-DAA-TN33385
AIAA Paper 2016-4060
E-19273
Meeting Information
Meeting: Atmospheric and Space Environments Conference
Location: Washington, DC
Country: United States
Start Date: June 13, 2016
End Date: June 17, 2016
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 147016.03.03.02.14.01
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Meteorological Instrument
Aircraft Icing
Wind Tunnel Tests
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