Experiments on Condensation of Water Vapor by Homogeneous Nucleation in Nozzles

Abstract

Condensation of water vapor in a highly supersaturated state was studied with steady flow of moist air in supersonic nozzles of different temperature gradients. With measured centerline static pressures, known initial conditions, and known nozzle geometry, the equations of motion could be solved. From these results heat addition to the flow owing to condensation could be determined. By estimating latent heats, condensate mass fractions and condensation rates have been found. It was inferred that at temperatures from 200 to 220°K the condensate was ice. Classical steady-state nucleation theories in conjunction with a droplet growth law were applied to solutions of the condensation integral equation. It was found that on this basis the onset of measurable condensation cannot be predicted from first principles. In a qualitative manner, however, the observations could be correlated with the theory. A contributing factor to the failure of nucleation theory is the lack of knowledge of material properties at the low temperatures in question. In conclusion, new work based on the findings of the conditions at the onset of condensation is suggested.

Condensation of Ammonia Vapor During Rapid Expansion

“…The lower curves are, respectively, the theoretical pressure distribution, and the isentropes. 16. considerations and for effect of heat addition alone, it is known that…”

“…Eliminating dr/dt from (13), (14), plus use of (6) .LIds: TF" = /P /P-.1 (16) For isentropic expansions…”

Formation de nano‐gouttelettes d'eau au sein d'un éjecteur à air induit: Une étude qualitative par visualisation de l'écoulement

“…L'air secondaire (debit massique rn2) est pour sa part aspire a travers 3 entrees disposees a 120" autour de la chambre de tranquillisation secondaire, avant d'6tre entraine vers la chambre de melange de la tuyere secondaire. Apres avoir acheve sa recompression dans le diffuseur, la melange air moteur-air induit est refoul6 dans I'atmosphere a pression Pa. Le La detente d'un fluide dans une tuyere supersonique etant generalement accompagnee d'un fort taux de sursaturation et donc d'un sous-refroidissement important, le processus de nudeation peut @tre suppose de nature homogene Wegener et Pouring, 1964;Hill, 1966). Les noyaux formes consistent alors en de tres petits agglomerats de molecules de I'espece condensee qui se constituent spontanement et non sur des corps etrangers comme c'est le cas lors d'un phenomene de nucleation heterogene.…”

2-D transonic flow with energy supply by homogeneous condensation: Onset condition and 2-D structure of steady Laval nozzle flow

“…Nozzle 8 of Wegener and Pouring (1964) was used as reference for the experiments as well as for the numerical calculations on the basis of the diabatic Euler method. It was built according to the data of Wegener and Pouring (1964).…”