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.

Fuel system for a marine vessel with a gaseous purge fuel container

Abstract: A fuel container for a marine propulsion system is provided with a pump and a hose connected to an outlet of the pump and disposed within the cavity of the fuel container. The hose is provided with an opening, formed through its wall, through which a fluid can flow under certain circumstances. The opening is disposed in an ullage within the container and allows gaseous elements to be purged from the container when flow is induced from the container back to a fuel reservoir.

Multiphase cfd simulations of solid propellant combustion in gun systems

Abstract: The Army Research Laboratory has developed a scaleable, 3D, multiphase, computational fluid dynamics (CFD) code with application to gun propulsion (interior ballistics) modeling. The NGEN3 code, which incorporates general continuum equations along with auxiliary relations into a modular code structure, is readily transportable between computer architectures and is applicable to a wide variety of gun propulsion systems. Two such systems are the Army's Modular Artillery Charge System (MACS) and the Future Combat System (FCS). The MACS is being developed for indirect fire cannon on both current and developing (e.g., Crusader) systems. The efficiency of the MACS charge is dependent on proper flamespreading through the propellant modules; a process that has been repeatedly demonstrated in gun firings, successfully photographed using the ARL ballistics simulator, and numerically modeled using the NGEN3 code. The FCS requires weapons systems exhibiting increased range and accuracy. One of the technologies under investigation to achieve these goals is the electrothermal-chemical (ETC) propulsion concept, in which electrically generated plasma is injected into the gun chamber igniting the high-loadingdensity (HLD) solid propellant charge. NGEN3 code development and application to the MACS and FCS is currently a DoD HPC Challenge Project (No. 112) and is being greatly advanced by access to the DoD high performance computers (HPCs). Associate Fellow AIAA. Propulsion Physics Team Leader, Ballistics and Weapons Concepts Division, Weapons and Materials Research Directorate. Mechanical Engineer, Propulsion Physics Team, Ballistics and Weapons Concepts Division, Weapons and Materials Research Directorate. This paper is declared a work of the U.S. Government and is not subject to copyright protection in the United States. INTRODUCTION A solid propellant gun system consists of a reaction chamber connected to a gun tube through which a projectile is guided once propelled by pressurization of the chamber. Chamber pressurization is accomplished by placing a solid propellant (SP) charge in the chamber and igniting it by various means. Current SP charges are generally complex structures consisting of hundreds or even thousands of distinct regularly formed (e.g., spherical, cylindrical) grains, which may be loaded in either regular or random arrangements. In addition to small-scale voidage between grains (i.e., porosity) many charges also contain large-scale voidage (i.e., ullage), which surrounds the entire charge (such as when the charge does not fill the entire chamber volume) or separates distinct subcharges (i.e., increments or modules) that together comprise the whole charge. The addition of energy to the chamber, usually near the gun breech, or rearmost end of the chamber, and in some cases through a tube extending along the centerline of the chamber, ignites the SP. In general, all of the grains are not ignited simultaneously, but an ignition flame spreads from the breech to the projectile base. The burning of the SP transforms chemical energy into heat as hot gases evolve from the surface of each grain of propellant. Initially the projectile resists movement allowing the pressure in the chamber to climb rapidly. Since the burn rate of the propellant is proportional to the pressure, hot gases are produced at an accelerated rate until peak pressure is reached in the chamber. Movement of the projectile down the gun tube, usually slight before peak pressure and much more significant afterwards, causes the chamber volume to increase, and generates rarefaction waves, which lower the pressure and thus the burn rate of the propellant. Upon ignition and burning, the gas dynamic flowfield in the gun chamber takes on a highly complex structure that includes the dynamics of propellant motion and combustion and various gas dynamic flow phenomena such as turbulent mixing, highly transient pressure waves, steep gradients in porosity and temperature, nonideal thermodynamics, and gas generation.

Hybrid Thermal Control Testing of a Cryogenic Propellant Tank

Abstract: This report presents the experimental results of a hybrid thermal control system, one that integrates a passive system (multi-layer insulation) with an active system (a mechanical cyrocooler) applied to cryogenic propellant storage. These experiments were performed on a 1.39 m diameter spherical propellant tank filled with LH2 while installed in an evacuated chamber. The tank heat transfer to the cryocooler was accomplished with a condenser installed in the ullage of the tank and mated to the second stage of the cooler, and by conduction, through copper leaves mated to the first stage of the cooler. The first hybrid system test was performed with both the condenser and the leaves, a configuration that had excess capacity to remove the heat entering the tank; the second test was performed with only the condenser, with a capacity closely matched to the tank heating rate. In both of these tests, the goal of zero boil-off was achieved.

Propellant Mass Gauging: Database of Vehicle Applications and Research and Development Studies

Abstract: Gauging the mass of propellants in a tank in low gravity is not a straightforward task because of the uncertainty of the liquid configuration in the tank and the possibility of there being more than one ullage bubble. Several concepts for such a low-gravity gauging system have been proposed, and breadboard or flight-like versions have been tested in normal gravity or even in low gravity, but at present, a flight-proven reliable gauging system is not available. NASA desired a database of the gauging techniques used in current and past vehicles during ascent or under settled conditions, and during short coasting (unpowered) periods, for both cryogenic and storable propellants. Past and current research and development efforts on gauging systems that are believed to be applicable in low-gravity conditions were also desired. This report documents the results of that survey.

Fuel tank safety system

Abstract: An apparatus and method for inerting the gas present in the ullage region of a storage tank for combustible liquids, e.g., a fuel tank containing a hydrocarbon liquid fuel, utilizes a molecular sieve zone (2, beds 12/14) which either (a) selectively adsorbs oxygen from the ullage gas to provide an oxygen-depleted return ullage gas, or (b) selectively adsorbs nitrogen from the ullage gas, which nitrogen is desorbed and conveyed by a purge gas to provide a nitrogen-enriched gas. The return ullage gas or the nitrogen-enriched gas is flowed to the ullage region (30, 130) in quantity sufficient to render the overall composition of gas in the ullage region (30, 130) non-combustible and non-explosive. The apparatus may include a compressor (22) or a vacuum pump to flow the ullage gas through the system, and a valving arrangement (16, 18) is used to control the flow of gases. Operation may be intermittent or continuous and may comprise pressure-swing adsorption/desorption to place one of molecular sieve beds (12, 14) on-line to adsorb oxygen or nitrogen from the ullage gas, while the other of molecular sieve beds (12, 14) is off-line being regenerated.