Effect of Gravity on Film Boiling Heat Transfer and Rewetting Temperature during Quenching

Abstract

This paper describes the experimental strategy developed to improve the modeling of liquidvapor flows during the chill down of rocket engines by cryogenic fluid in microgravity. A similarity analysis is performed to determine the relevant dimensionless numbers for the design of an experiment similar to engine flows. A literature review on reduced gravity quenching experiments, and on rewetting temperature and film boiling heat transfer shows the lack of validated models for microgravity. Experimental results obtained with the quenching of a glass tube by FC72 during parabolic flight are presented. Especially the impact of gravity and subcooling on rewetting temperature and film boiling heat transfer is investigated. Results show an increase in rewetting temperature, and a decrease in film boiling heat transfer under reduced gravity in agreement with the literature. The compar-B. Verthier (B) · C. Colin ison of 0 g flow pattern with corresponding tests on ground points out a behavior at 0 g closest to 1 g upflow than 1 g downflow.

Transient cryogenic chill down process in horizontal and inclined pipes

“…The end of the chill down process is usually characterized by a steady pipe wall temperature and the pipe is cooled enough to be rewetted. During chill down, whole boiling curve can be noticed at each pipe location [2]. Many definitions of rewetting temperature is available in literature such as (i) Leidenfrost temperature, minimum film boiling temperature, (ii) quenching temperature from thermocouple observations, and (iii) temperature at which critical heat flux occurs.…”

“…Kawanami et al [20] observed higher quench front velocity and heat transfer coefficient in microgravity for vertical quenching of a glass tube with liquid nitrogen. Verthier et al [2] conducted reduced gravity chill down experiments using glass tube and FC72. Results showed decrease in film boiling heat transfer and an increase in chill down temperature under these conditions.…”