SUMMARY

The proposed research will investigate the hydrodynamics of cryogenic fluid flow through microporous media based on first principles. The systems of interest are the fillers of regenerators in pulse tube and Stirling cryocoolers and will be modeled through 3D computational fluid dynamics. Both steady state unidirectional flow and periodic flow will be investigated. The second part of the proposed research is aimed at a critical review of existing literature dealing with pool and flow boiling of cryogens relevant to spacecraft fuel systems including LO2, LH2 and LCH4, and the development of stand-alone computational routines for accurately modeling two-phase flow and boiling of such cryogens. These computational routines will be developed to be compatible with NASA's flow system simulation tool Generalized Fluid System Simulation Program (GFSSP). A critical assessment of all existing experimental data pertinent to two-phase and boiling of the aforementioned cryogens will be performed, a reliable set of boiling data will be selected and the most accurate boiling correlations will be determined. The applicability of well-established two-phase flow and boiling closure relations for the aforementioned key cryogens of interest for space fuel systems will be determined. A roadmap for experiments addressing potential gaps in the available experimental data dealing with LO2 and LCH4 will be proposed.