Ali Heyadat

Bio: Ali Heyadat is an academic researcher. The author has contributed to research in topics: Pressure regulator & Cryogenics. The author has an hindex of 1, co-authored 1 publications receiving 16 citations.

Cryogenic Pressure Control Modeling for Ellipsoidal Space Tanks

Abstract: A computational fluid dynamics (CFD) model is developed to simulate pressure control of an ellipsoidal-shaped liquid hydrogen tank under external heating in normal gravity. Pressure control is provided by an axial jet thermodynamic vent system (TVS) centered within the vessel that injects cooler liquid into the tank, mixing the contents and reducing tank pressure. The two-phase cryogenic tank model considers liquid hydrogen in its own vapor with liquid density varying with temperature only and a fully compressible ullage. The axisymmetric model is developed using a custom version of the commercially available FLOW-31) software. Quantitative model validation is ,provided by engineering checkout tests performed at Marshall Space Flight Center in 1999 in support of the Solar Thermal Upper Stage_ Technology Demonstrator (STUSTD) program. The engineering checkout tests provide cryogenic tank self-pressurization test data at various heat leaks and tank fill levels. The predicted self-pressurization rates, ullage and liquid temperatures at discrete locations within the STUSTD tank are in good agreement with test data. The work presented here advances current CFD modeling capabilities for cryogenic pressure control and helps develop a low cost CFD-based design process for space hardware.

Cryogenic Fluid Management Technology For Moon and Mars Missions

Abstract: In support of the U.S. Space Exploration Policy, focused cryogenic fluid management technology efforts are underway within the National Aeronautics and Space Administration. Under the auspices of the Exploration Technology Development Program, cryogenic fluid management technology efforts are being conducted by the Cryogenic Fluid Management Project. Cryogenic Fluid Management Project objectives are to develop storage, transfer, and handling technologies for cryogens to support high performance demands of lunar, and ultimately, Mars missions in the application areas of propulsion, surface systems, and Earth-based ground operations. The targeted use of cryogens and cryogenic technologies for these application areas is anticipated to significantly reduce propellant launch mass and required on-orbit margins, to reduce and even eliminate storage tank boil-off losses for long term missions, to economize ground pad storage and transfer operations, and to expand operational and architectural operations at destination. This paper organizes Cryogenic Fluid Management Project technology efforts according to Exploration Architecture target areas, and discusses the scope of trade studies, analytical modeling, and test efforts presently underway, as well as future plans, to address those target areas. The target areas are: liquid methane/liquid oxygen for propelling the Altair Lander Ascent Stage, liquid hydrogen/liquid oxygen for propelling the Altair Lander Descent Stage and Ares V Earth Departure Stage, liquefaction, zero boil-off, and propellant scavenging for Lunar Surface Systems, cold helium and zero boil-off technologies for Earth-Based Ground Operations, and architecture definition studies for long term storage and on-orbit transfer and pressurization of LH2, cryogenic Mars landing and ascent vehicles, and cryogenic production via in situ resource utilization on Mars.

Dynamic Behaviors of Liquid in Partially Filled Tank in Short-term Microgravity

Abstract: The oscillation of liquid/gas free surface in a partially filled storage tank caused by an abrupt drop of gravity level is of critical importance for the fluids management in space. In present study we investigate the dynamic behavior of free surface in tank models (tubes) using water as the working medium utilizing the Drop Tower Beijing, which can provide a 3.6s short-term microgravity condition. Meanwhile, the corresponding numerical simulation using volume of fluids (VOF) methods was carried out. It is shown that the dynamic behavior of free surface, which belongs to the typical phenomenon of capillary flow, is affected by the properties of working medium and the geometry and surface properties of the storage tank (especially the contact angle) jointly. The numerical simulation could capture the major characteristic oscillation frequency of free surface revealed by experiment. The oscillation frequency of free surface increases with the increasing air fraction and remains nearly constant at large air fraction. For the same air fraction, the oscillation frequency significantly increases with the decreasing tank diameter.