Title

Applications in quenching heat transfer: Liquid quenching of turbine disks and chill down in cryogenic fluid transfer lines

Date of Completion

January 2003

Keywords

Engineering, Aerospace|Engineering, Mechanical

Degree

Ph.D.

Abstract

Liquid quenching of turbine disks concerns multiphase heat transfer (HT) during heat treating in the manufacture of gas turbine disks. Chill down (CD) in cryogenic fluid transfer lines concerns rapid cooling of cryogenic propulsion systems during startup. ^ Quenching experiments were conducted on gas turbine disk models to obtain internal and surface temperatures. Three different disk models were tested and analyzed. The three disk models represent steps in the evolution from a simple disk shape to a scale model of an actual gas turbine disk. Experimental temperature data were used in finite element models of the disks to calculate heat transfer coefficients (h). Analysis of h for all of the quench cases studied led to a better understanding of the mechanisms of quenching HT. Insight into the mechanisms of quenching HT and the effects of forced quenchant flow led to generalizations of h with respect to local disk geometry. Correlations for single-phase and boiling HT were developed for selected quench cases. Recommendations for further study of this interesting and challenging topic are given. ^ A numerical model to predict CD in cryogenic transfer lines was developed. Three CD cases using hydrogen are solved: (1) a simplified model amenable to analytical solution, (2) a realistic model of superheated vapor flow, and (3) a realistic model of initially subcooled liquid flow. The first case enables a comparison of the numerical model results with an analytical solution. The other cases are numerical models which provide quantities of interest in CD applications. For example, of great interest in CD applications is the ability to predict accurate values of CD time (the time required to achieve steady-state cryogenic flow). Sample CD times and other results of interest are discussed in the thesis. ^