Ullage

About: Ullage is a research topic. Over the lifetime, 501 publications have been published within this topic receiving 4704 citations. The topic is also known as: headspace.

Development and Qualification of the Propellant Management System for Viking 75 Orbiter

Abstract: tube. This paper describes the development and qualification of the surface tension system and includes results of low-g drop tower tests of scale models, l-# simulation tests of low-g large ullage settling and liquid withdrawal, structural qualification tests, and propellant surface-tension/contact-angle studies. Subscale testing and analyses were used to evaluate the ability of the system to maintain or recover the desired propellant orientation following possible disturbances during the Viking mission. This effort included drop tower tests to demonstrate that valid wick paths exist for moving any displaced propellant back over the tank outlet. Variations in surface tension resulting from aging, temperature, and lubricant contamination were studied and the effects of surface finish, referee fluid exposure, aging, and lubricant contamination on contact angle were assessed. Results of movies of typical subscale drop tower tests and full scale slosh tests are discussed.

Finite element solution of low bond number sloshing

Abstract: The dynamics of liquid propellant in a low Bond number environment which are critical to the design of spacecraft systems with respect to orbital propellant transfer and attitude control system were investigated. Digital computer programs were developed for the determination of liquid free surface equilibrium shape, lateral slosh natural vibration mode shapes, and frequencies for a liquid in a container of arbitrary axisymmetric shape with surface tension forces the same order of magnitude as acceleration forces. A finite volume element representation of the liquid was used for the vibration analysis. The liquid free surface equilibrium shapes were computed for several tanks at various contact angles and ullage volumes. A configuration was selected for vibration analysis and lateral slosh mode shapes and natural frequencies were obtained. Results are documented.

US Army activities in multidimensional modeling of electrothermal-chemical guns

Abstract: Progress towards developing a first-principles capability to simulate the dominant physical processes in an electrothermal-chemical (ETC) gun is described. The computational model is the CRAFT Navier-Stokes solver, which implements advanced implicit/upwind numerics with strongly coupled chemistry and generalized grid dynamics. The model provides a framework for incorporation of physics submodules. One ETC design examined was a central ullage tube surrounded by a HAN-based propellant. Initial nonreactive simulations in which the ullage tube is initially filled with air at a calculated uniform pressure and temperature and the plasma jet continues to inject into the combustion chamber indicate a potential for a highly structured flow field. >

Refrigeration of superconducting magnet systems

Abstract: A refrigeration system includes a dewar and a refrigerator/liquefier which meets the variable demands of a superconducting magnet within the dewar. The system is sized to meet average loads over a defined duty cycle, and is variably operable to meed demands. In the preferred embodiment, a first supply of fluid circulates through a "condenser" element positioned in a dewar ullage to liquefy a separate supply of fluid in the dewar, and to refrigerate a pulsed cryogenic load therein, such as a superconducting magnet. A portion of the first supply of fluid may be diverted to refrigerate a second pulsed cryogenic load, such as magnet current leads permanently connected to the magnet. The dewar includes a cold gas vapor storage chamber separate from the dewar ullage, and the chamber is preferably located within the inner core of a solenoid superconducting magnet for compact and thermally efficient design. Responsive, independent adjustment of refrigeration to pulsed cryogenic loads is made possible.