Heat and mass transfer mechanisms have been characterized in physical models of human cadaver airways to simulated depths of 305 m with various gas mixtures. Such characterizations offer a detailed understanding of the effects of environmental pressures, gas composition, and respiratory rates (RMV) on the body cooling capacity of the respiratory airways. Empirical heat transfer relationships in the form -Nu = AReNPr1/3 are derived for the oral and nasal passageways during inhalation and exhalation flows. -Nu, Re, and Pr are the dimensionless Nusselt, Reynolds, and Prandtl numbers, respectively. The Nusselt and Reynolds numbers are based on the diameter and gas flow rate in the trachea and are applicable to Reynolds number values up to 70,000.
Measurements of respiratory resistance by an interrupter technique were made in six subjects during a Navy saturation dive to 457 m. Repeated measurements were made at five depths with complete pulmonary function testing after the dive. Increase in resistance was about linear with gas density (rho). Three smokers exhibited a significantly steeper slope of the respiratory resistance versus rho relationship than three nonsmokers. The disparity in resistance among the divers became considerable only at great pressure. Likewise, the predictions of two contradictory fluid dynamic theories agreed fairly well with our data and with each other over the densities explored and disagreed greatly with our data only at higher pressures.
ISa. DECLASSIFICATION/DOWNGRADING SCHEDULE 16. DISTRIBUTION STATEMENT (of th.le Report) Approved for public release; distribution unlimited. 17. DISI RIBUTION STATEMENT (of the abetract entered in Block 20, It different from Report) 10. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reveree olde if necee*ary and identify by block num, ber) MK 14 CCSDS Evaluation Analysis 20. ABSTRACT (Continue an reveree side It neceeeary and Identity by block number) The MK 14 Closed Circuit Saturation Diving System was evaluated over a depth range of 167 FSW to 1100 FSW to test its ability to support a diver performing heavy work. During graded exercise, helmet C0 2 , differential pressure, and inspired gas temperature as well as diver heart rate were measured. Analysis of the data indicates that the MK 14 can support a diver performing heavy work (3.0 LPM 02 consumption), FORM DD IJAN 1473 EDITION OF NOV 65 IS OBSOLETE OVER-S/N 0102-014-660tl UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Date A wad) UN,-ASSTFIED-'.-INJITy CLASSIFICATION O THIS PAGE(Whei Data ffnterod) 20. (Continued) and has successfully met it's design objectives. UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAOE
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